Copyright: ® 1999 Cat Soft - all rights reserved
Citation: On-line help for Serv-U v2.5a


Welcome
Contents

General Information

Contents

FTP Serv-U Features

FTP Serv-U Registration Information

Getting Help

FTP Serv-U User Interface

The Main FTP Serv-U Window

Using the Register FTP Serv-U dialog box

The About FTP Serv-U dialog box

Entering your FTP Serv-U registration key

Exiting FTP Serv-U FTP Server

Finding information on logged-in users

Viewing logged-in users

Finding out what commands a user is sending

Forcing users off of your server

Configuring a FTP Serv-U Server

Setting up general parameters for your server

Setting up multi-homed IP

The directory listing cache

Configuring logging

Setting up sign-on and sign-off messages

Setting up IP access rules

Setting up upload/download ratios

Files that are not counted in u/d ratios

Configuring Users and Groups of Users

Setting up users

Setting up groups of users

Setting general user configuration

Setting upload/download ratios for a user

Setting up disk space quota

Setting up IP access by users

FTP Serv-U Concepts

Using file access rules

Using directory change messages

Using directory links

About passive mode data transfers to servers behind a firewall

Defining user-specific sign on and signoff messages

Special features of passwords in FTP Serv-U

FTP Serv-U symbolic message parameters

Defining IP rules

Printing via FTP

One-time password processing

Copyright & Disclaimer

The FTP server program FTP Serv-U and its documentation are copyright Cat Soft. It is distributed as shareware, giving you the right to try it for a period of 45 days. If you intend to use FTP Serv-U after the initial try-out period, you are obliged to pay the registration fee.

This software is provided by the regents and contributors 'as is' and any express or implied warranties, including, but not limited to, the implied warranties of merchantability and fitness for a particular purpose are disclaimed.  In no event shall the regents or contributors be liable for any direct, indirect, incidental, special, exemplary, or consequential damages (including, but not limited to, procurement of substitute goods or services; loss of use, data, or profits; or business interruption) however caused and on any theory of liability, whether in contract, strict liability, or tort (including negligence or otherwise) arising in any way out of the use of this software, even if advised of the possibility of such damage.


The Main Serv-U Window
The Main FTP Serv-U Window

When you run FTP Serv-U and show the server window, you will see the main server window.  This window consists of a menu bar, a tool bar with icons for important functions, the server messages window, and a status bar showing server activity at-a-glance.  From this window you can monitor the server and access all of the management functions of your FTP Server.

The menu options and the toolbar icons each access similar functions, each of the functions are described below.

Menu Items

The following functions are available for each menu item:

•	File

On-line - This option will take the FTP server on-line, to serve requests, or off-line.  A check mark in the menu will indicate the status of the server, and the result of your actions will appear in the message window.

File Logging - Toggles the accumulation of messages in the configured log file.  The state of the toggle button indicates whether logging is turned on.  This option is grayed out if logging to a log file is not configured.

User Info - Displays the User Info dialog .  This dialog shows information about current users of your FTP Serv-U FTP Server.

Exit - Shut down your FTP Server.  If users are still logged in, FTP Serv-U will display the Exit FTP Serv-U dialog.

•	View

Toolbar - Toggles the display of the toolbar and icons on the main FTP Serv-U window.  A check mark on the menu will indicate the status of this option.

Menu Images - Toggles between showing menus with little images or plain text. In case you are using a screen reader (for the blind) it is advised to switch off showing images in menus.

•	Edit

Screen Logging - Toggles the accumulation of messages to the message display. Is handy to temporarily suspend the logging of messages to the screen.

Copy - Copies selected text from the message display to the clipboard.

Clear - Clears all messages from the message display.

•	Setup

FTP-Server - Displays the Setup FTP-Server dialog box.  This dialog allows configuration of general server parameters.

IP-Access - Displays the Setup IP-Access dialog box.  This dialog allows configuration of security based on the IP-Address of clients.

Logging - Displays the Setup Logging dialog box.  This dialog allows configuration of logging parameters.

Messages - Displays the Setup Messages dialog box.  This dialog allows specification of welcome and goodbye messages to be displayed to clients.   Note that user-specific sign on and signoff messages may also be defined with FTP Serv-U.

Users - Setup Users dialog box.  This dialog allows addition and management of users of your FTP Serv-U FTP Server.

Groups - Displays the Setup Groups dialog box.  This dialog allows addition and management of user groups.

•	Help

Help Topics - Brings up the Table of Contents window of the FTP Serv-U help system.

Help Overview - Brings up the main FTP Serv-U help window.

Serv-U Support - Connects you to the FTP Serv-U Support Web site using your Web browser.

Purchase Serv-U Electronically  - Connects you to the online registration page of the FTP Serv-U Web site.

Serv-U Ordering Information - Connects you to the FTP Serv-U ordering information Web site.

Register Serv-U - Displays the Register FTP Serv-U dialog box.  This box displays information on registration, and allows entry of your registration key.

Check for Serv-U Update - Checks the Internet for the most recent version of FTP Serv-U and displays this information in your Web browser.

About Serv-U - Displays the About FTP Serv-U dialog box.

The following functions are available from the toolbar:

 On-line

This button will take the FTP server on-line, or off-line.

 User Info

This button will display the User Info dialog. This dialog shows information about current users of your FTP Serv-U FTP Server.

 Copy Text

This button will copy the selected text from the message window to the clipboard.

 Logging

This button will toggle on-screen logging on and off.

 Clear Log

This button will clear all messages from the message window.

 Setup Users

This button will bring up the Setup User dialog box. This dialog allows addition and management of users of your FTP Serv-U FTP Server.

 Setup Groups

This button will bring up the Setup Groups dialog box. This dialog allows addition and management of user groups.

 Help

This button will bring up the on-line help system.

 About

This button will bring up the About FTP Serv-U dialog box.


User Info Dialog
Viewing logged-in users

The User Info Dialog displays information on users who are currently using your FTP Serv-U FTP Server.

The upper part of this dialog shows a list of all users currently connected to your server.  By clicking with the mouse on one of the users you can get extra information about that user in the lower part of the window.  Please notes that viewing this information will slow down server performance.

The IP-Name displayed on this dialog is found by a reverse DNS lookup of the IP number.  This lookup may take some time to return the IP-Name.  Also, note that many IP numbers do not have an associated name.

Freeze List

Pressing the Freeze List button will pause updating of the user info information.

Spy on User

This button will pop up the FTP Commands/Requests window.  This window will show all of the FTP commands that the user is sending to your server.

Kill User

Pressing the Kill User button will pop up a Kill User dialog that will allow you to forcefully remove a user from your server, and offer you options to keep this user from logging on again.


Setup FTP Server Dialog
Setting up general server parameters

The Setup FTP Server dialog allows you to set general server configuration information.

FTP port number

Port number that the server will listen on.  Default value is 21.

Max. speed

You may limit the network bandwidth that FTP Serv-U will use by specifying maximum value here (in Kbytes/second).  If left blank, the maximum available bandwidth will be used.

Max. no. of users

Sets maximum number of simultaneous users.  A setting of 0 will allow no users, leaving this option blank will set no limit on the number of users.

Auto-start as system service

For Windows 95 users, this checkbox will let you use FTP Serv-U as a system service.  This means the server will start immediately after starting your PC, and it will continue running even when Win95 users log out and back in again.

Enable security

Global setting to enable or disable all security. Default is enabled.  Disabling security will allow anybody on the network to delete/change/copy everything on your PC!  Do not ever leave the Enable security option unchecked if your computer is connected to the Internet.

Encrypt passwords

When checked, FTP Serv-U uses the exact same encryption mechanism as UNIX to store passwords in encrypted form. Since passwords are stored in the SERV-U.INI file this will also ensure no one can read or recover the passwords. Once the passwords are encrypted they can never be decrypted again. When this checkbox is unchecked passwords are stored as clear text.

Check anonymous passwords

'Netiquette' prescribes that users logging into an FTP server under the 'Anonymous' user name should use their E-mail address as their password. When this option is checked, FTP Serv-U will check the passwords which anonymous users enter to log into the server.  (These basic checks make sure the password resembles an e-mail address.  No verification of valid e-mail addresses is done). If left unchecked the server will accept anything for the anonymous user's password.

Block anti time-out schemes

Many FTP client programs have an automatic mechanism that prevents users from being logged out after a certain inactivity time. When checked, FTP Serv-U will count how long a user has been idle in a way that prevents client programs that periodically send automatic commands to the server from keeping idle connections open.

Delete partially uploaded files

If checked, partially uploaded files that did not complete successfully are automatically deleted.  By default, this is unchecked, so partial transfers can be resumed where they left off.

Block FTP_bounce attacks

When checked, the server will only allow file transfers between the FTP client and server, and block any direct server-to-server transfers (FXP). This prevents a type of malicious attack known as 'FTP_bounce attacks' (see CERT advisory CA-97.27).

Block users who connect more than XX times within YY seconds for ZZ minutes

Use this option to protect your FTP server from 'hammer attacks'.  When enabled, users are blocked from connecting to your server in rapid succession. If they make more than XX connections within YY seconds their subsequent connections will be terminated immediately upon connection and they will be blocked for the next ZZ minutes. No message is sent to the user when he is blocked, which makes using this option very low overhead for the server.

Use all lower case for files/dirs

This option is only available in 32-bit versions of FTP Serv-U.  For some operating systems it is easier to have to deal with only lower-case, in particular if the OS is case sensitive.

The following 'file' options are available.  Text may be entered directly, or the ellipsis button may be pressed to bring up a file selection dialog box.

Primary dir. change file

Primary file to display directory change messages to the user.

Secondary dir. change file

Secondary file to display directory change messages to the user.  This message is used if the primary message file is not found.

Primary file containing'links'

Primary file that contains a list of directory links to merge into a directory display.

Secondary file containing'links'

Secondary file that contains a list of directory links to merge into a directory display.  Used if the primary message is not found.

Note:

Beside the file entry text boxes, there are '…' buttons.  These are for browsing, to select a file, and they will call up your text editor with the selected file, and create the file if it did not exist yet.  Keep in mind though that there is one thing these buttons will not do for you: They will copy the entire path including drive and directories. If you wanted a different message in different directories you have to manually remove the path so only the file name itself is left.  For more information, please check the sections on using directory change messages and using directory links for details about these functions.

The following buttons are available from the Setup FTP Server dialog:

IP Homes

Brings up the Setup Multi-Homed IP dialog. If your server has multiple IP addresses this allows the server to respond differently to each IP address.

U/D Ratios

Brings up the Setup Upload/Download Ratios dialog.  This allows you to set the server to require X number of uploads per Y number of downloads.

Dir. Cache

Brings up the Directory Listing Cache dialog. FTP Serv-U can cache directory listings so that the next time a listing is requested by a client, the server does not have to retrieve it from the disk.  This dialog configures the listing cache.


Setup IP Access dialog
Setting up IP access rules

The Setup IP Access dialog allows you to restrict access to your FTP Serv-U FTP Server by IP address.  Client IP addresses can be allowed or denied access according to rules specified here.  This dialog can be accessed from the Main FTP Serv-U Window.  This dialog can also be used when setting IP access rules for specific user or group accounts from the Setup Users and Setup Groups dialogs.

Edit Rule

To add a rule, first specify whether this is a Deny access rule (deny access to an IP address or address mask), or an Allow access rule (allow access based on an IP address or address mask).

IP addresses can be specified with wild cards.  The following special characters may be used.  For more information, check Defining IP access rules.

•	The star '*' character, which functions as a wildcard for checking the IP address.  A '*' in a section of the IP number indicates that all numbers in that part of the IP address qualify as a match.

•	The question mark '?' character functions as a wildcard in IP names only, to stand for a single character.

•	The hyphen '-' character functions as a range in an IP address.  For example, the number 152.2.200-202.103 will allow the numbers 200, 201, or 202 in the third part of the IP address.

Rule List

The Rule list on the right hand side shows the current list and order of IP rules.  Rules can be added and removed from the list using the Add and Remove buttons to the left of the rule list.  Also, the order of the rules may be altered using the Up and Down buttons on the bottom of the rule list.

NOTE:  THE ORDER OF THE RULES IS IMPORTANT!  When a client contacts the server, the rules are looked at from top to bottom in the list of rules.  The first matching rule applies and evaluation is stopped.  Please consult the user documentation if this is not clear.

By default, all IP addresses are allowed.  Once the first rule is entered, then a user must pass the access rules before access is granted.  In order to access the server, a user has to match an 'allow' rule.  If a user's IP matches a 'deny' rule, the access is denied.


directory links
Using Directory Links

Links are names of files and/or directories that appear in the directory listing but they are not in the directory that the user is listing. Rather, they point to the actual directory or file and appear to the user as such.  When a link is deleted through FTP Serv-U (i.e. via FTP) the actual file or directory is gone! The great value of links is in showing users they have access to other directories and disk drives, which may not normally be visible when they do a directory listing. The user can then simply change directory to a link and thus change to a completely different drive and directory.

Windows shortcuts as links

FTP Serv-U has two ways of working with links. It can will use Windows shortcuts as links, or it can read them from a text file. To use a Windows shortcut as a link, simply create the shortcut through Explorer, and point the shortcut's target to the link destination. The target can be either a file or a directory. The next time the user lists the directory containing the shortcut it is shown as a link, and will behave as a link when used with other FTP commands.

For links to show in a user's directory listing the user needs list access to the shortcut and the target of the shortcut. FTP Serv-U will not show links that point to the same directory as that which the user is listing.

Text files as links

FTP Serv-U can also work with links is by reading them from a text file. Different link files may be specified for each directory. The file name is entered via the Setup - FTP Server dialog. The server setup specifies a primary and secondary link file. During use the server will first try to find the primary link file, and if that one does not exist it will try the secondary file name.

There are several ways to specify which file FTP Serv-U should use for links:

•	Use a file name by itself, without a path, for example LINKS.TXT. This makes the server look in the user's current directory for a file with this name and if found it is merged into the directory listing. This is the way to set up different link files for each directory.

•	Use a full path name, for example C:\FTP\LINKS.TXT.   When a full path is specified, the same directories are shown in each and every directory. If links should not be shown in every directory, use a file name only for the link file, not a full path.

•	Leave out the drive letter, for example \FTP\LINKS.TXT, which means FTP Serv-U adds the current drive to the name and then looks for the file. Useful for setting up links that change per drive, but not per directory.

Tip:

If the link file's attribute is 'hidden' and Hide hidden files is enabled in the miscellaneous section of the user setup or group setup then users won't see the file itself appear in their directory listings while they still get to see the links.

In a typical situation, specify a relative path name for the primary link file, and an absolute path name for the secondary link file. For example, enter the file name LINKS.TXT as the primary file name and FTP Serv-U will look for this file in the users current directory. This allows definition of a different LINKS.TXT files for each directory, typically with links specific to that directory. Then put all the links that should always be shown to the user in a secondary link file with an absolute path name, such as C:\SERV-U\ABSLINKS.TXT. A good candidate for the secondary link file would be a link to the user's home directory.

Here is an example of a link file.  Each line of the file describes a different link. First comes the link name, which is what the user is going to see in the directory listing, then a '|' which acts as a separator, and finally the file or path that the link should point to. Here is an example link file:

D-Drive         | d:\

CD-ROM          | f:\

Home            | ~

Fun Stuff       | g:\public\games

One up          | ..

Pointless       | \junk\..\more\..

Poem            | c:\culture\poem.txt

The '~' character in the example above has a special meaning, it is a short form for 'the user's home directory'.

As far as the user is concerned links behave like the real thing: They can be used for 'change directory' if it's a directory, 'download' for a file etc. The only difference is that a link is deleted via FTP using some FTP client program, the file or directory it points to will get deleted but the link will continue to show up in the directory listing. Needless to say that it is the responsibility of the administrator that the links in a link file point to something that makes sense.

Notes:

•	Links to drives and directories outside of the user's home directory will not work with the Show path relative to homedir option enabled.

•	FTP Serv-U will only show links in a directory listing to which the user has list access of the link's destination.

•	Links pointing to the user's current directory are not shown, to avoid infinite looping if the user downloads an entire directory.

•	To the FTP client FTP Serv-U tries to resemble a UNIX FTP server as closely as possible. This means links are merged into the directory listings as UNIX style links. It is up to the FTP client program how these are shown to the user. Some show them as files (even if the links point to directories), some show them as directories (even if the links point to files), and some let the user select how links should be shown in the FTP client's setup.


Directory Listing Cache dialog
The directory listing cache

Creating a directory listing is a slow process for the server: It has to access the disk, determine if the user has access to each of the elements of the listing, and sort it. The Directory Listing Cache dialog allows you to configure a cache that will hold directory listings created by user requests.  If a user requests a directory listing that already exists in the cache, then the server will not recreate it, thus greatly improving server performance.  This dialog is accessed from the Setup FTP-Server dialog.

Enable directory cache

This checkbox switches use of the directory cache mechanism on or off. The directory-listing cache is switched off by default in the 16-bit version of FTP Serv-U (Win3.1/WFW3.11), and enabled in the 32-bit version (Win95/Win98/NT).  The reason it is switched off in the 16-bit version is because it cannot detect directory and file changes.  In the 32-bit version, these changes are automatically detected, and those directory listings are removed from the cache so that directory listing requests are always up-to-date.

Maximum size

Under Windows 95 and NT, the cache is on by default, and set to a maximum of 20 different listings. When the cache fills up, then the next new request will cause FTP Serv-U to expire the least recently requested directory listing and replace it with the new one.

Time-out

The time-out value determines how long directory listings remain in the cache, regardless of how often they are requested by clients. The default value is 600 seconds (10 minutes).

Flush cache

Pressing this button will remove all directory listings from the cache.

The default of 20 listings and 600 seconds should work well for most servers.  For servers with typically many different users, listing many different directories, it may be beneficial to increase the cache size. Remember that a larger cache size will consume more memory and FTP Serv-U will spend more time on cache house-cleaning tasks!


FTP Commands Requests window
Finding out what commands a user is sending

The FTP Commands/Replies screen allows you to 'spy' on a logged-in user.  This dialog is reached from the User Info dialog.

Select a user from the user list box in the User Info dialog, and you may then view the FTP commands and server replies for that user as they occur.  This dialog tracks the user selected in the User Info Dialog, so you may switch between logged in users to monitor their activity. If you determine that a user is misbehaving on your system, you may use the Kill User dialog to force them off of your server.


Kill User dialog
 Forcing users off of your server

The Kill User dialog allows you to force a user off of your server.  In addition, you will be presented with options to keep the user off your server permanently.  This dialog is reached from the User Info dialog box.

Select a user from the User Info dialog, and press the Kill User button.  This Kill User dialog will appear, and you may remove the user, and set options to prevent that user from accessing your server again.

The following options may be entered when killing a user:

Refuse IP access in the future for XXX.XXX.XXX.XXX

No further connections from this IP address will be accepted. This is accomplished by placing the IP address in FTP Serv-U's IP access list. This means it is possible edit the IP address and use wildcard characters like '*' and '?', and ranges with '-', just like those in IP access rules.

Disable account

The FTP Serv-U account displayed in the dialog will be disabled.  Note that the account can be subsequently re-enabled using the Setup Users dialog.

Calculate subnet

Pressing this button automatically calculates the proper wildcard IP address to cover the entire subnet where the client is connecting from. It takes the user's subnet class (A, B, or C) into account.


Register Serv U dialog box
Using the Register FTP Serv-U dialog

If you decide you want to continue using the FTP Serv-U server beyond the try-out time, then it is a simple matter to register your server.  You may use the Register FTP Serv-U dialog to assist in registering your product.  In addition, you use the Register FTP Serv-U dialog to enter your software key that you received upon registration.

You reach the Register FTP Serv-U dialog box from the Main FTP Serv-U Window under the 'Help' menu item.  Choose the Register Serv-U menu item.

The Register FTP Serv-U dialog gives you a quick reference of important registration and help information.  In the Registration frame, you can get the contact information of Deerfield, the distributor of FTP Serv-U.  In addition, several Web links are available by clicking on the URL links.  Clicking on one of the FTP Serv-U URL's will bring up the described Web page in your browser.

Enter key

Brings up the Enter Key dialog, allowing you to enter your FTP Serv-U registration key.

Purchase

Brings up the FTP Serv-U purchase page using your Web browser, allowing you to register on-line.


Setup Groups dialog box
Setting up groups of users

The Setup Groups dialog box allows you to configure user options at a group level.  Users can then be assigned to groups using the Setup Users dialog.  Users assigned to groups inherit the configuration of the group to which they are assigned.  Individual users can be further configured if they have some different setting from their group.

The Setup Groups dialog can be reached from the Setup menu of the Main FTP Serv-U Window.

Note that the Setup Groups dialog is the same as the Setup Users dialog, with the exception of the User name field.

On the left-hand side of the dialog, a selection list of configured groups is displayed.  You may select a group from the list and see the details for the group displayed on the right hand side of the window.

Group Name

Every user can be part of a group.  Groups can be used to hold common settings shared by several users.  If you create a user, and assign him to a group, then all settings will be inherited by the user, including password, home directory, and path access rules.  To override a setting, simply alter that setting for specific user in the group.

•	To add a new group, press the New button on the right hand toolbar, then enter the desired data.  To modify a group, select a group, and edit the data.  When the configuration is complete for your group, press the Store button to save the changes.  The OK button will also save the changes and dismiss the dialog box, returning you to the Main FTP Serv-U window.

•	This group name field may be changed while viewing a configured group.  If the name is changed, then pressing Store will store the currently displayed settings under the new group.  This can be handy for quickly copying groups.

Password

The password for the group is stored by FTP Serv-U.  If the encrypt passwords option is selected in the Server Setup dialog, then FTP Serv-U will store the password with UNIX style encryption.  To change a password, type the new password in and press Store.

Home Directory

The home directory is the directory that the user will be placed into immediately after logging in.  Home directories must be specified with the full path, including the drive letter.

Notes

This text area allows the entry of notes for the system manager.  Any text may be entered here.

File Directory Access Rules

These rules determine which files and directories a group has access to.  Please see the section on access rules.

The following dialogs are accessible from the Setup Groups dialog:

User/Group Miscellaneous Setup dialog

Pressing the Misc. button will bring up the User/Group Miscellaneous dialog.  This dialog allows the setting of various parameters, such as the appearance of the group's directory path, the contents of a group's directory, the login message file for the group, etc.

User/Group Upload/Download Ratios Setup dialog

Pressing the U/D Ratios button will bring up the  User/Group Upload/Download Ratios Setup dialog.  This dialog allows you to require X bytes to be uploaded to your server for each Y bytes of data downloaded.

User/Group Disk Quota dialog

Pressing the Quota button will bring up the User/Group Disk Quota dialog.  This dialog allows you to set quotas for disk space for the group.

Setup IP-Access

Pressing the IP Access button will bring up the IP-Access dialog.  This dialog allows group-specific IP access rules to be defined.


Setup Logging dialog box
Configuring logging

The Setup Logging dialog allows you to configure server logging options.  Options are available for both on-screen and file logging.  Debugging level messages are also available.

Screen & File Logging Options

The logging options are shown on the left side of the screen.  For each type of information that can be logged, there are two options.  The first check box indicates that this particular information should be logged to the message area of the main FTP Serv-U window.  The second checkbox indicates that the particular information should be logged to a file.  Further down on the left side are options for server debugging messages of various types.  Again, check the option for on-screen or file logging for any information that is of interest to you.  Please be aware of performance impacts, and the size of log files, when selecting this information.

Do not log clients from these IPs

At the bottom of the left-hand side, there is a text box where IP addresses, in comma-separated format, can be added.  Any client connecting from one of these addresses will not show up in the logs. Its primary purpose is to avoid repetitive logging of maintenance connections like those from server checking software like WatsUp.  The addresses can contain wild cards. Please consult Defining IP rules for more information on formatting IP addresses with wildcards.  Here is a brief summary:

•	The star '*' character, which functions as a wildcard for checking the IP address.  A '*' in a section of the IP number indicates that all numbers in that part of the IP address qualify as a match.

•	The question mark'?' character functions as a wildcard in IP names only, to stand for a single character.

•	The hyphen'-' character functions as a range in an IP address.  For example, the number 152.2.200-202.103 will allow the numbers 200, 201, or 202 in the third portion of the IP address.

Enable logging to file

This check box is available to enable or disable logging to the file specified in File name.

File name

Should contain a full path and file name of the file in which FTP Serv-U writes logging information. In case a log file rotation option is selected this file name will be used as the base of the actual name, and a date will automatically be added to it.

Automatically rotate log file

The log file can be rotated periodically by checking one of the rotation options, this will cause FTP Serv-U to automatically start a new log file at the start of the specified interval. This uses the file name as specified in File name, with a date added to that name. Automatic log file rotation can be done on a Daily, Weekly, Monthly, Yearly basis. In case of Weekly log file rotation a new file is started on Sundays.

IP address logging

IP address logging automatically writes a file at the specified interval of all the server IP addresses. Its main purpose is for those with a dynamic (changing) IP address. There are programs that automatically update a Web page with the current IP address that they find in a local file, using one of these would keep FTP links on a Web page pointing to the current IP address.

Select font

Brings up the standard Windows font selection dialog to select the font FTP Serv-U will use for logging to the screen. The currently selected font is shown below this button.

Default font

Reverts any log font selection to the default logging font, which is 8 point Arial.


Setup Multi Homed IP dialog
Setting up multi-homed IP

An FTP server installed on a computer can have multiple IP addresses.  The Setup Multi-Homed IP dialog allows you to configure your server to respond differently, depending on the IP address to which the user connects.  Each IP address that your server responds to can have a different set of users with a different set of access rights.  This dialog is reached from the Setup FTP-Server dialog.

This dialog has a main list showing all of the IP addresses configured for your server.  You may add or remove these entries by clicking on the Add and Remove buttons on the left-hand side.

To add an entry, enter the data in the detail boxes on the left-hand side, then press the Add button to add the IP address to your server configuration.  The entry now appears in the list box.

To remove an entry, first select the home IP in the list box, then press the Remove button to remove the IP address from your server configuration.

Home IP address

This combo box will display the IP addresses available for your machine.  You may select an IP address from the list, or type a new address.

Descriptive name

This name can be entered for descriptive purposes, i.e. typical use would be the symbolic IP name for that specific IP address.  This field is optional.

IP for passive mode

This text box can be used to specify the IP address outside clients should use when doing passive mode data transfers to servers behind a firewall.

Server listens on home IP addresses only

Checking this box makes the server listen on the specified home IP addresses only, instead of listening and responding to incoming connections on all available IP address on the computer. Its purpose is in case a system has multiple IP addresses and FTP Serv-U should only service a selected few of these, for example because there is another FTP server servicing the remaining IP addresses.

By default this box is not checked, and FTP Serv-U sets up a single listening socket which responds to incoming connections on all available IP addresses. When this box is checked a separate socket is set up for each IP home, to service connections coming in on that particular IP address. This means that if hundreds of IP homes are specified this will result in hundreds of listening sockets, which can severely cripple server performance. Recommended use is only for those cases where it is needed, with no more than a few dozen IP homes.


Setup Signon Signoff Text dialog box
Setting up sign-on and sign-off messages

The Setup Messages dialog allows you to set up default sign-on and sign-off messages that are displayed to the user.  This dialog can be reached from the Main FTP Serv-U Window setup menu.

Server home IP

Select the IP address of the server home IP for which the sign-on and sign-off message files should be set up. FTP Serv-U can display a different message file for a different home IP. In case no specific message file is specified for a certain home IP the server will use the files from the'<<All IP homes>>' setting. In case no IP homes have been set up the only available selection will be'<<All IP homes>>', and this is the one to be used to set up message files.

Signon message file

Your server can display a welcome message every time a user connects to it.  This is the sign on message. It is the first message sent to the user, even before the user has logged in.

Signoff message file

This displays a good-bye message when the user leaves.   This is the last message sent to the user before he is disconnected.

These messages can contain symbolic parameters for server-specific information.  When FTP Serv-U displays a sign on or sign off message, it will substitute dynamic data for the specified parameters.  Also note that custom user-specific login messages may be specified in User Setup dialog and the Group Setup dialog.

Messages are cached by the server. As long as any message file changes are made through the message setup dialog box the server will immediately show the changes. If message files are changed outside FTP Serv-U it can take up to 15 minutes before the changes are picked up by the server.


Setup Upload Download Ratios dialog
Setting up upload/download ratios

Upload/download ratios allow you to require users to upload data at some ratio to the data that is being downloaded.  That is, the user gets credit for uploads that he can then 'spend' by downloading data. These ratios are set up by the user or by the group using User/Group Upload/Download Ratios dialog.

You may want certain files to be 'free'.  That is, you may not wish to count certain downloads against any 'credit' that a user may have accrued by uploading files.  Free files may be specified using the Free Files Setup dialog .


About Serv U dialog box
About FTP Serv-U dialog box

The About FTP FTP Serv-U dialog allows you view descriptive information about your FTP Serv-U software, including the name of the person, company, or institution to which FTP Serv-U is registered, and version information.

The About FTP Serv-U dialog can be reached from the Main FTP Serv-U Window .  Under the 'Help' menu item, click the 'About Serv-U…' menu item.

This dialog contains hot-links to the FTP Serv-U Web site, and the Cat Soft Web site, the site of the program author. The 'Deerfield' image contains a hot-link to the main page of Deerfield.com's Web site (FTP Serv-U is but one of the many programs sold by Deerfield).  These links may be clicked, and the Web site will be displayed in your Web browser.

FTP Serv-U will try to determine the servers' IP addresses and display them on the right side of the dialog box next to the IP label. This can be a convenient way to determine your server's current IP address in case of a dynamic IP address. In case the server has multiple IPs only the first 4 are shown.


Setup Users dialog box
Setting up users

The Setup Users dialog allows you to manage users of your FTP Serv-U FTP server.   User ids and passwords can be configured, home directories can be specified for users, users can be assigned to groups, and file permissions can be specified.  In addition, upload/download ratios can be configured, IP access can be specified by user, and disk quota can be set.

This dialog can be reached from the 'Setup' menu option of the Main FTP Serv-U window .

On the left-hand side of the dialog, a selection list of configured users is displayed.  You may select a user from the list and see the details for the user displayed on the right had side of the window.

User Name

The current user name selected from the left hand Users list, or the name for the new user, may be entered.

To add a new user, press the New button on the right hand toolbar, then enter the desired data.  To modify a user, select a user, and edit the data.  When the configuration is complete for your user, press the Store button to save the changes.  The OK button will also save the changes and dismiss the dialog box, returning you to the Main FTP Serv-U window.

This user name field may be changed while viewing an existing user.  If the name is changed, then pressing Store will store the currently displayed settings under the new user name.  This can be handy for quickly copying users.

Note that there are two special user names,'** Default **' and 'Anonymous'.  These special user names have a particular function.  The'** Default **' user ID is used to hold default settings when no settings exist for a user.  The 'Anonymous' user can be used for guests on your FTP server.  The 'Anonymous' user does not require a password.  Instead, FTP Serv-U will ask users who log on as 'Anonymous' for an E-mail address.

Home IP

When running your server with Multi-homed IP configured, the Home IP item will appear on the User Setup dialog, otherwise, it is not visible.  This drop down box will show the configured home IP addresses.  You may assign a user to a specific IP home. Multiple users can exist with the same user name but a different IP home. These are separate user accounts, each with different access rights, home directories, and other settings.  In this way your server will appear different to a user depending on which server IP address he is connection to!  Note also that a user can be set up on all IP addresses configured for your server by selecting the'<< All IP Homes >>' entry in the drop-down. The selection of which user account the server will use when a client connects to the server is as follows: FTP Serv-U will first try to find a home IP specific user account, and use this if available. If there is no home IP specific account the server will look for an account that has'<< All IP Homes >>' specified.

Group Name

Every user can be part of a group.  Groups can be used to hold common settings shared by several users.  If you create a user, and assign him to a group, then the user will inherit all settings, including password, home directory, and path access rules.  To override a setting, simply alter that setting for the individual user.  Note that that the special 'Anonymous' user ID ignores any group settings.  Groups are set up using the Group Setup dialog.

Password

The password for the user is stored by FTP Serv-U.  If the 'encrypt passwords' option is selected in the Server Setup dialog, then FTP Serv-U will store the password with UNIX style encryption.  To change a password, type the new password in and press 'Store'.  There are several special features of passwords in FTP Serv-U.

Home Directory

The home directory is the directory that the user will be placed into immediately after logging in.  Each user must be assigned a home directory.  This assignment can be done on the Group Setup dialog.  Home directories must be specified with the full path, including the drive letter.

Notes

This text area allows the entry of notes for the system manager.  Any text may be entered here.

File Directory Access Rules

These rules determine which files and directories a user has access to.  Please see the section on access rules.  These access rules also control rights to print via FTP, another function of FTP Serv-U.

The following dialogs are accessible from the Setup Users dialog:

User/Group Miscellaneous Setup dialog

Pressing the Misc. button will bring up the User/Group Miscellaneous dialog.  This dialog allows the setting of various parameters, such as the appearance of the user's directory path, the contents of a user's directory, the login message file for the user, etc.

User/Group Upload/Download Ratios Setup dialog

Pressing the U/D Ratios button will bring up the User/Group Upload/Download Ratios Setup dialog.  This dialog allows you to require X bytes to be uploaded to your server for each Y bytes of data downloaded.

User/Group Disk Quota dialog

Pressing the Quota button will bring up the User/Group Disk Quota dialog.  This dialog allows you to set quotas for disk space for the user.

Setup IP-Access

Pressing the IP Access button will bring up the IP-Access dialog.  This dialog allows user-specific IP access rules to be defined.


access rules
Using file access rules

FTP Serv-U's file access rules facility  allows specification of file access per directory and even per file for each user.  These access rules can be specified in the Setup Users and Setup Groups dialogs.  Note that file access rules also control user rights to print via FTP, please refer to that help topic.

There are eight different types of access information that can be set, four that apply to files, three for directories, and the final one has a special meaning. For file access these are:

•	Read access, allow files to be downloaded from the FTP server.

•	Write access, allow files to be uploaded to the FTP server, but not changed, deleted, or renamed.

•	Append access, allows appending to existing files and is needed for resuming uploads. Append access automatically includes write access.

•	Delete access, allow the user to change files, rename, or delete them. Having delete access automatically includes append and write access (although it does no harm to specify all of them).

•	Execute access, is meant for executing files through FTP, i.e. for running DOS and Windows programs remotely. This should be used with care, since allowing 'execute' access can easily lead to security holes.

Then there are three items that deal with directories:

•	List access, allows the user to retrieve a directory listing.

•	Make access lets the user create new directories at this path, i.e. the user can make subdirectories.

•	Remove allows the user to delete directories.

The final item is somewhat special:

•	Inherit means that the access rule automatically applies to all subdirectories of the path, i.e. the rule is inherited by subdirectories.

To allow a user to use the 'change directory' FTP command to get into a directory any of the rights is sufficient. So, a user that has read, write, append, delete, execute, list, make, or remove can change to the directory in the access path. Conversely, if a path is specified without any access rights (except maybe for 'Inherit') then the user has no access what-so-ever to this path.

A user has write access to a file or path, but no delete access, can upload files to the server as long as they do not exist already. This is good for an upload directory, because it allows uploads without the chance of changing previously uploaded files.

To allow a user to resume an upload the user normally needs at least 'Append' access to the file to resume an upload. Only 'Write' access will not usually do since that does not allow the user to change any existing file (including the partially uploaded file). There is an exception to this rule though, if a number of conditions are met: The user has to connect from the same sub-net as where the original upload took place from, and log into the same user account. The user has to resume within 12 hours after the upload attempt failed. The user must resume at the end of the partially uploaded file (the resume mechanism in FTP actually allows users to resume anywhere). The previous will work for many situations, but not all. Some ISPs have multiple sub-nets and a user may get assigned an IP address from another sub-net and thus be unable to resume. Still, it is a useful mechanism in case you can not grant append access to a directory.

Execute access is meant for remotely starting programs and usually applies to specific files. Be careful in granting this right: For example, allowing a user to start COMMAND.COM also means that this user can delete anything on your hard disk! More on using this in the How to execute programs via FTP with FTP Serv-U section of your user documentation.

If a user needs to be able to see a directory listing, list access must be granted. This can also be used in the opposite way: For example, a user may need to be able to upload files to an upload directory, but that same user should not see and certainly not download anything that is already there. Only specifying the 'write' right and leaving 'list' access unchecked could do this.

When a user executes an FTP command concerning files or directories, the user's access path list is checked to see if the command should be allowed to proceed.  The list is evaluated from top to bottom and evaluation stops as soon as an applicable rule is found

THE ORDER OF THE PATH ACCESS RULES IS IMPORTANT! Unless the access rules are in the right the correct result will not be achieved!

An 'Anonymous' FTP site needs a directory tree with all the files the users might want to download, for which they need read access. An upload directory where users can upload new files is also needed, although other users should not be able to immediately download these files, since they may be  checked for viruses first. So, this upload directory needs write but no read access. Assume all files and directories are placed on the 'Y:' drive, under the 'ANONFTP' directory. The 'UPLOAD' directory is also created here for uploads. To accomplish this in FTP Serv-U one would create the user 'Anonymous' with the following access path rules (and in this order):

Y:\ANONFTP\UPLOAD	- write, inherit rights

Y:\ANONFTP	- read, list, inherit rights

Reversing the rules will not work: If a user tries to write to the upload directory, the security mechanism will check against Y:\ANONFTP and conclude that UPLOAD is a subdirectory, so the rule applies because inherit is checked, and the rule grants only read and list access. Please take note that write access does not allow a user to get a directory listing of the UPLOAD directory, so not only won't a user be able to download anything from there, the user cannot even see what files are uploaded.

If the drive letter is left out of a path, it applies to all drives. So, a fast way to get full access to all files on all drives is:

\	- read, write, append, delete, list, make, remove, and inherit rights

The same mechanism that determines access to directories also applies to files. It is possible to grant access to specific files on a per-file basis. To take the previous example about the anonymous FTP server. We want to put a file 'SECRET.TXT' in the ANONFTP directory, but nobody should be allowed to read it. The access path list would look like this:

Y:\ANONFTP\SECRET.TXT	- no rights

Y:\ANONFTP\UPLOAD	- write, inherit rights

Y:\ANONFTP	- read, list, inherit rights

Again, the order of the paths is important! The directory access rights do not have any meaning for files. Alternatively, if SECRET.TXT were a directory instead of a file, the above settings would keep users completely out of this directory. FTP Serv-U will hide all files and directories a user does not have list access to. They do not show up in directory listings, so in the above example the SECRET.TXT file would be truly secret.

FTP Serv-U also supports wildcards in access rules. An example to illustrate some of the possibilities:

Y:\ANONFTP \SECRET.TXT	- no access

Y:\ANONFTP \*.TXT	- read, list, inherit

Y:\ANONFTP \??BRA	- read, list, inherit

The second rules makes sure the user only sees file and directory names ending on .TXT, nothing else. Access (read access) is also restricted to these files. On top of that, the file SECRET.TXT is not shown and the user has no access to it. Finally, the last rule will show and give access to anything ending on BRA with no extension and two characters in front of it. So, if there is a directory named ZEBRA the user will see it and have access to it. Note that just as before the order of access rules are very important. FTP Serv-U looks at them from top to bottom and stops as soon as an applicable rule is found.

Single names without a path may be used, and it will be applied to every file and directory name, on every drive. Moreover, the names can contain wildcards. This is typically very useful to block access to certain files for all the directories the user has access to. Say one does not want users to upload (or rename) .EXE files. Say files named LINKS.TXT are used for link info and should not be shown to the user. A realistic setup for a user with home directory of C:\USERS\JOE would be:

*.EXE	- no access

LINK.TXT	- no access

C:\USERS\JOE	- read, write, delete, list, makedir, removedir, inherit access


User/Group Miscellaneous dialog
Setting up general user configuration

The User/Group Miscellaneous dialog allows configuration of general settings for a user or group.  This dialog can be reached from the User Setup dialog, and the Group Setup dialog.

The following settings are available from this dialog, they apply equally to users and groups of users:

Disable account

Setting this checkbox will disable the account for the user, the user will not be able to log in.

Show path relative to homedir

When enabled, FTP Serv-U will show all the directories a user deals with as if they are relative to the user's home directory.  That is, the user sees his home directory as root ('/').  This only works for directories that are at or below a users home directory.  If enabled, a user is restricted to his home directory and the directories below it, even if there are access rules that would allow the user to go outside these.

Hide 'hidden' files

If enabled, the user will be unable to see any files with an attribute of 'hidden' in their directories. This can be useful to hide files like those containing 'directory links' or 'directory change messages'.

Always allow login

When enabled, a user can log in even when the maximum number of users for the server is reached.  This is a handy setting for an administrator account.

Allow only X login(s) from the same IP address

Prevents a user from concurrently logging in more than a certain number of times. Note that some FTP client programs automatically log in a new session for each file transfer (including Microsoft's Internet Explorer!), so the number of concurrent logins should preferably not be set too small when this option is enabled. A minimum of three is recommended to ensure trouble free operation for the users.

Allow user to change password

If checked, the user can change their password from an FTP client. Only certain FTP clients support this option. A recommended client that can change passwords remotely is FTP Voyager from Deerfield.com, see www.ftpvoyager.com

Max. speed

The maximum speed setting allows you to limit the bandwidth consumed by the user. This maximum applies to each client that logs in. I.e. if the maximum bandwidth is set to 5 Kbytes/second it means that each client that logs into this account will get a maximum throughput of 5 Kb/sec.

Idle time-out

Time before idle connections are dropped.  It is suggested that this number be set to not less than 5 minutes, so clients with a bad Internet connection will be able to complete file transfers.

Max. no. of users

This number specifies the maximum number of users with the same user name that can be concurrently logged in.

Login message file

This text area can hold an absolute or relative path to the login message text to display to the user.

Password type

This drop down allows you to select normal passwords from the client, or to expect a hash-code generated in S/KEY one-time password format.  Unless doing S/KEY one-time passwords, this should remain set to 'Regular Password'.


User/Group Upload/Download Ratios Setup dialog
Setting upload/download ratios for a user or group

The User/Group Upload/Download Ratios Setup dialog allows you to set up rules requiring X number of uploads for each Y number of downloads.  These ratios can be by number of files, or by bytes.  Also, these ratios can be set per session, or over multiple sessions.

Setting upload/download ratios allows you to require users to upload data at some ratio to the data that is being downloaded.  That is, the user gets credit for uploads that he can then 'spend' by downloading data.  An initial credit can be specified.

The following fields may be configured from this dialog, the settings apply equally to users and user groups:

Enable U/D ratios

This checkbox allows you to turn upload/download ratios on or off.

Count files per session

The ratios apply to files uploaded or downloaded in this session.  The ratio will be calculated by the number of files uploaded or downloaded.

Count bytes per session

The ratios apply to files uploaded or downloaded in this session.  The ratio will be calculated by the number of bytes uploaded or downloaded.

Count files for all sessions

The ratios apply to files uploaded or downloaded across sessions.  The ratio will be calculated by the number of files uploaded or downloaded.

Count bytes all sessions

The ratios apply to files uploaded or downloaded across sessions.  The ratio will be calculated by the number of bytes uploaded or downloaded.

Uploads

The number of bytes/files uploaded.

Downloads

The number of bytes/files downloaded.

Preset/Current

The number of bytes/files credited to the user.  This is the initial credit value a user receives if counting per session, or accumulated across multiple sessions if counting for all sessions.

Notes:

Note that each user logging into an account with 'per session' type of ratios will receive its own initial credit as specified in Preset/Current and any uploaded files (and credit received) will only be retained for the duration of that session. As soon as the user logs out any accumulated credit is lost.

In case an 'over all session' type of ratios is specified there will be only one credit count for all users logging into the account, i.e. everyone using the account shares the credit count. For this type of ratios the accumulated credit is retained after the user logs out and used as the starting value for the next user logging into the account.

Note that certain files may be marked as 'free' using the Setup Upload/Download Ratios dialog from the Setup FTP-Server dialog.  These files do not count against downloads in computing upload/download ratios.


User/Group Disk Quota dialog
Setting up disk space quota

You may limit the amount of disk space that users consume using the User/Group Disk Quota dialog.  This dialog allows you to set a limit for a user.  FTP Serv-U will keep track of uploads, downloads, and file deletions to calculate a running total of current disk usage.

Enable disk quota

This checkbox turns disk quota enforcement on or off.

Current X Kb

This sets the current amount of data that the user has on the hard disk.  Note that FTP Serv-U keeps a running total based on uploads and downloads. An initial value is entered here, and FTP Serv-U will then keep track of any future activity.

Maximum X Kb

This number is the maximum amount of disk space a user may consume.

Calculate current

Pressing this button makes the server calculate the user's current disk usage by looking at the user's home directory and the directories below this. The calculated value is then placed into the Current entry.


Serv-U Registration Information
FTP Serv-U Registration Information

Registering FTP Serv-U is easy.  Open up the Main FTP Serv-U Window, click the Help menu, and then click the Register Serv-U option.  You will see the Register FTP Serv-U dialog.  Press the Purchase button on that dialog, and you will be taken to the FTP Serv-U Registration Web site.  You will find registration information there, and you can even register online.

Once you have registered, and you receive your FTP Serv-U key, you may return to the Register FTP Serv-U dialog.  Press the Enter key button on that dialog, and the Enter Key dialog will appear.  Enter and store your key, and you are on-line with FTP Serv-U!


FTP_bounce attacks

In 'active mode' an FTP client can send a 'PORT' command to a server which tells the server to which IP address and port number it should connect for the next data transfer. There is normally no limitation on the address or port numbers, so a client can instruct the server to connect to any other system rather than to the FTP client itself. This can be abused by malicious clients to probe a network where the server opens up a connection to another server that the client does not normally have access to. FTP_bounce attacks are described in more detail in CERT advisory CA-97.27.

For normal file transfers between server and client there is no need for the server to ever connect to anything other than the client for data transfers. However, there is one legitimate use that deviates from this: The FTP protocol allows for direct transfers from one server to another, bypassing the client. This is called FXP, and some FTP clients can facilitate in setting up such transfers. Typical use would be to transfer large amounts of data between servers on a high-speed network, where the FTP client is on a slow link. In such a case the FTP client opens a connection to both servers and instructs them to directly transfer files between them, using the proper combination of 'PORT' and 'PASV' FTP commands. In case FTP_bounce attacks are blocked at the server receiving the 'PORT' commands such direct transfers will not work.


passive mode data transfers to servers behind a firewall
About passive mode data transfers to servers behind a firewall

If FTP Serv-U is running behind a firewall with address translation, passive mode data transfers (as used by all Web browsers) do not work. The reason is that the IP address of the server is not the same as the IP address outside users should use to connect to the server. FTP Serv-U does not know this, and when the FTP client program asks for its passive IP address it will give the wrong (internal) address.

What is needed is some way to tell FTP Serv-U what IP address it should hand out to FTP clients when they want to do a passive mode data transfer, the right address is the IP address the outside world should use to connect to the server. This can be done via the Setup - Multi-Home IP dialog.  In that dialog box is an entry for IP for passive mode, that is where the IP address to report to FTP clients goes.

Its actual use is very much like the multi-homed IP setup. For example, say a server is behind a firewall, and has an IP address 192.168.0.10. The outside world accesses the server by using, for example, address 243.56.78.1. To make passive mode work, enter'192.168.0.10' for Home IP number, some description at Descriptive name and'243.56.78.1' at IP for passive mode. After pressing the Add button a special IP home is created, which does passive mode address translation. To make the passive IP address work for FTP users make sure to select it in the Setup - Users dialog as the user's IP home.

The above assumes the firewall is set up to pass all the needed packets on to the server. In particular, this means the firewall has to allow incoming TCP connections to port 21 on the server, allow outgoing TCP connections from port 20 (for regular mode data transfers), and allow incoming TCP connections to any random port over 1023 on the server (for passive mode transfers). Depending on what the firewall allows to pass it may be that despite passive mode address translation it is still not possible to use passive mode for data transfers.


Defining user-specific login messages

FTP Serv-U allows definition of login messages that are specific to a user account. These messages are defined in one or more text files and the file name can be filled out in the Miscellaneous User/Group Information dialog.

The file name entered in the Message file field can have several forms:

•	An absolute path with a drive, for example C:\FTP\LOGMES.TXT. This will make FTP Serv-U use this particular file.

•	Only the name, and no path, for example LOGMES.TXT. This will cause FTP Serv-U to look in the user's home directory for this file and if it is there it will be displayed to the user. If no file is found, no message is displayed.

•	A path but no drive letter, for example \FTP\LOGMES.TXT. This means that FTP Serv-U will add the drive of the user's home directory to make a full path.

The latter two ways of specifying the file can be very useful for groups, i.e. with just a single file name set up all the users that are part of that group will see a custom login message.

Note that in the login message text, special symbolic parameters provided by FTP Serv-U may be used. These parameters are dynamically filled in with server information at display time.


Free Files Setup dialog
Files that are not counted in u/d ratios

When specifying upload/download ratios for your server, certain file downloads may be identified as not charged against a user's credit.  The Setup Upload/Download Ratios dialog allows specification of the files that should be free.  This dialog is reached from the Setup FTP-Server dialog.

The dialog will show a list box of all current 'free files'.  New files may be added by typing in the file name, and pressing the 'Add' button.  To remove a file from the 'free' list, select the file from the list box and press the 'Remove' button.

Files may be specified in several ways:

•	A file name with no path information may be entered.  This means that any file in any directory with that file name will be 'free'.  In the above example, a file called index.txt is free whether it is in the c:\freefiles directory, or the d:\users\bob directory.

•	A file name with a path, but no drive, may be entered.  This type of specification indicates that that file, on that path, is free on any hard drive.  If a file is specified as '\homes\misc\readme.txt' is specified, then that full path on the d: drive or the f: drive will be 'free'.

•	A full path and drive may be entered.  This type of specification will limit the free file to the specific directory on the named drive.

•	Wild cards may be used in any of the above situations.  A '*' may be used to indicate a directory name or file name or extension.  A '?' character may be used to indicate on character in a directory name, or file name.


Enter_Key_Dialog
Entering your FTP Serv-U registration key

Once you register your FTP Serv-U FTP server, you will receive a registration key that will allow you to operate your server with none of the try-out limitations.

To enter your FTP Serv-U registration key, open up the Register FTP Serv-U dialog, and click the Enter Key button.  This brings up the Enter Key dialog.  In this dialog, you may enter your registration key.

On the left-hand side of the dialog, you may enter your key in the text box.  You also have several options for entering your key:

From file

This option lets you enter your key from a file. Pressing the button brings up a Windows file dialog.  You may enter the name of a text file that contains your FTP Serv-U key. The file to enter would normally be a file containing the E-mail message sent to you upon registration.

Paste

This will paste the key information into the key area. For this to work you have to previously copied the registration key to the clipboard, for example by highlighting it in your E-mail program and using its 'copy' option.

Copy

This option copies your registration key to the clipboard.


special features of passwords in Serv-U
Special features of passwords in FTP Serv-U

Password Encryption

FTP Serv-U uses the exact same encryption mechanism as UNIX to store passwords encrypted.   FTP Serv-U gives you the option to use this encryption on the Setup FTP-Server dialog.  There is no known way to retrieve the clear text version of passwords once they are encrypted. To make life for automated addition/deletion of users easier, uncheck this checkbox.  This means FTP Serv-U will store passwords as clear text in the SERV-U.INI file.

There is one more mechanism FTP Serv-U can use for passwords, called One Time Passwords  . This can be selected for each individual user account using the miscellaneous user setup dialog box .

Please note that changing this option will not change FTP Serv-U's existing passwords, only the way they are interpreted by the server. This means that changing this option will leave existing users unable to log in, unless you re-enter their passwords in the server setup. In other words, it is better to determine how FTP Serv-U should store passwords before entering large numbers of users.

Changing Passwords

Once a password is stored only the word '<<Encrypted>> ' is displayed in the password field. This is to indicate there is a password. Existing passwords cannot be edited, since the original is truly lost and only the encrypted form is kept. The only way to change it is by typing in a completely new one.

Anonymous Passwords

Check anonymous passwords is an option on the Setup FTP-Server dialog.  This option is not enabled by default.  If enabled, FTP Serv-U will check the 'password' which anonymous users enter to log into the server. These checks are very basic, all it does is make sure the 'password' resembles an E-mail address (which is the custom for anonymous 'passwords'). No checks are done to make sure the E-mail address actually exists, only its format is checked. In case it is obvious the 'password' can not be an E-mail address FTP Serv-U will refuse access to the user. Some Web browsers (most notably MS Internet Explorer) will not send a regular E-mail address as their anonymous password. To allow access for those using such a Web browser leave this option unchecked.

Empty Passwords

An empty password field does not mean that the user has no password. FTP Serv-U assumes that all users need a password and will try if there is a group setting and look at that for the password. If no password can be found then access will be denied to the user. If it is desirable to set up a user with no password (i.e. the user name is enough to log in), put the text '<<None>>' in the password field.


symbolic message parameters
FTP Serv-U symbolic message parameters

FTP Serv-U FTP Server can display various types of messages:

•	Sign-on/sign-off messages

•	User specific login messages

•	Directory change messages

There are several symbolic parameters that can be entered in the message text.  These parameters are expanded while being sent to a client. They all begin with '%'. Here is the complete list:

Time/date:

%Time	- displays the current time on your PC

%Date	- displays the current date on your PC

Server statistics:

%ServerDays	- displays the number of days the server has been running

%ServerHours	- displays the number of hours the server has been running

%ServerMins	- displays the number of minutes the server has been up

%ServerSecs	- displays the number of seconds the server has been up

%ServerKbUp	- displays the no. Kbytes uploaded to the server since server start

%ServerKbDown	- displays the no. Kb downloaded from the server since server start

%ServerFilesUp	- displays the no. of files uploaded to the server since server start

%ServerFilesDown	- displays the no. of files downloaded from the server since server start

%LoggedInAll	- displays total no. of logged in users since server start

%ServerAvg	- displays the average server throughput since server start

%ServerKBps	- displays current server bandwidth use

Server settings:

%MaxUsers	- displays the maximum no. of users, as set in 'Setup - Server'

%MaxAnonymous	- the maximum no. of anonymous users, as set in 'Setup - Server'

User info:

%Name	- displays the user's login name

%IP	- displays the user's IP number or name if available

%Dir	- displays the user's current directory

%Disk	- displays the user's current disk drive

%DFree	- displays the amount of free space on the user's current disk in Kb

%FUp	- displays the number of files uploaded by the current user

%FDown	- displays the number of files downloaded

%FTot	- displays the total number of files transferred

%BUp	- displays the number of Kbytes uploaded by the user

%Bdown	- displays the number of Kbytes downloaded by the user

%BTot	- displays the total number of Kbytes transferred

%TconM	- displays the total connect time in minutes

%TconS	- displays the connect time in seconds - to be used with '%tconm'

%RatioUp	- displays the 'upload' ratio part for UL/DL ratios

%RatioDown	- displays the 'download' ratio part for UL/DL ratios

%RatioCredit	- displays the current download credit for UL/DL ratios (Kb or 'files')

%QuotaUsed	- displays how much disk quota is used in Kb

%QuotaLeft	- displays how much disk quota is left in Kb

%QuotaMax	- displays the maximum amount of disk space that can be used in Kb

Number of users:

%UNow	- displays the current number of Serv-U users connected

%UAll	- displays the number of users since the server was started

%U24h	- displays the number of users in the last 24 hours

%UAnonAll	- all currently logged in anonymous users

%UAnonThisIP 	- all anonymous users logged into this IP home

%UNonAnonAll 	- all non-anonymous users currently logged in

%UNonAnonThisIP	- all non-anonymous users logged into this IP home

%UThisName	- all current users with the current user name logged into this IP home

The file upload and download message directives are for the current session only (i.e. They do not show the aggregate over multiple sessions

The '%ServerDays', '%ServerHours', '%ServerMins', and '%ServerSecs' directives are meant for use together. The number of hours is what's left after the number of days is subtracted, and the same goes for the number of minutes and seconds.

Here is an example message:

Welcome, it is %time on %date, and you are user number %unow of %maxusers

Over the last 24 hours, %u24h people have visited this site

Please keep in mind that the average client has only 80 characters per line, and the first four are taken up by the reply code. Please be brief, 70 characters should generally be considered a safe maximum.


directory change messages
Using directory change messages

FTP Serv-U allows definition of specific messages to display to users when they enter a directory.  Different directory change messages may be set up for every directory.

The directory change message text should be stored in a file. This file is then specified In the Setup - FTP Server dialog.

The file name may be specified in two different ways:

•	Absolute path file names - (for example C:\FTP\CDMES.TXT).  This will display that file for each directory change.

•	Relative path file names - It is possible to use a file name only without the path, for example CDMES.TXT. This will make FTP Serv-U look for and display the file with that name, in the directory into which the user is changing This is the usual way to use directory change message files, since this makes possible a different message for each directory.

The Setup - FTP Server dialog has room for a 'primary' and 'secondary' directory change message file. When looking for a message file, FTP Serv-U will first try the primary file name. If there is no file name specified in there, or the file cannot be found, the server will try to find the secondary file name. This is very useful in case there should be a specific directory change message files for some directories, using a relative file name as the primary directory change message file. An absolute file name can then be specified as the secondary directory change message file. This will show the users the primary file message when available, and the secondary one if there is no primary.   (For example because it's a CD-ROM, so it is not possible to place directory change message files in its directories).

Like sign-on and sign-off messages, FTP Serv-U provides symbolic message parameters that are dynamically substituted into the displayed messages.  These parameters allow inclusion of dynamic information in messages.

Trick:

If the Hide hidden files feature is enabled in the miscellaneous user setup, directory change messages may be hidden from the user by making it 'hidden'. Hidden files are files with the DOS/Windows 'hidden' attribute set, something that can be done using the DOS program 'Attrib' or by changing the 'properties' of a file in Win95 (using the right mouse button). So, if directory change message files are hidden they won't show up in the directory listings while users still get to see the messages.


Getting Help

If you are having problems working with FTP Serv-U and need help, here are some tips:

•	Check the on-line help.  FTP Serv-U has context-sensitive help, so try getting help on a dialog that does not make sense to you.

•	Check the user documentation.  FTP Serv-U has a comprehensive user manual.

•	Check the FTP Serv-U Web site, www.ftpserv-u.com.

•	Check the Discussion Forum and Pre-Sales Tech Support: forum1.deerfield.com/~ftpserv-u

•	Use the Tech Support Request Form: www.ftpserv-u.com/support.htm

•	Try Tech Support Email: support@ftpserv-u.com

•	General information Email: info@ftpserv-u.com

•	Sales information Email: sales@ftpserv-u.com

•	For bug reports, of if you want to offer suggestions you are most welcome to drop a line to the author at address: Rob@cat-soft.com

•	The Cat Soft Web site can be found at: www.cat-soft.com

FTP Serv-U Discussion List

There is a discussion list by E-mail for FTP Serv-U where you can ask questions and discuss FTP Serv-U related topics. At the moment of this writing the list is a thriving community of over 550 subscribers. Many of these are very knowledgeable Internet professionals. An excellent place for your questions!  To subscribe to the FTP Serv-U mailing list, send an E-mail message to:

serv-u-request@cat-soft.com

With only a single line in the message body, which should read:

subscribe

This will return a message from the list manager within a minute or so, explaining in detail how to post messages to the list and related matters.

There is also a digest version of the discussion list. By subscribing to this list you will receive one message each week with all the messages posted to the list during that past week. To subscribe to the digest list, send an E-mail message to:

serv-u-digest-request@cat-soft.com

with a single line in the message body, reading:

subscribe

If you want to look through previous postings to the mailing list please take a look at the FTP Serv-U list archive at:

www.pacemail.com/hyper/

  Reporting Bugs

Please report bugs to the author at Rob@cat-soft.com.

Tips for reporting bugs:

•	Most important: Can you get the same bug to appear by repeating certain actions? Please try hard; without a recipe for repeating a bug, it's going to be very hard to track it down.

•	Which version of FTP Serv-U are you using? And is this the 16- or 32-bit program? You can find this information in the 'help - about' menu choice of FTP Serv-U.

•	What TCP/IP and WinSock stack are you using? Brand/type and version number please. What operating system (DOS version and Windows or Windows-For-Workgroups, Windows 95/98, NT version x.xx)?

•	Please indicate also if this bug is merely cosmetic or of vital importance for using FTP Serv-U. Somewhere in between is possible as well of course. By the way, I consider security-related bugs very important!


Serv-U Features
FTP Serv-U Features

FTP Serv-U is a 'server' program, also called a 'daemon'. The term daemon comes from ancient Greek mythology. There, the Daemons were half-gods, acting as messengers between the people on earth and the gods. This FTP server acts, likewise, as a messenger for file transfer between FTP clients and your computer. Once started it sits in the background waiting for a client to contact it and after communications are established, acting out the client's commands.

There are FTP servers (and clients) for many different systems. This particular program is meant for PCs running MS-Windows that have a WinSock version 1.1 compatible TCP/IP stack installed. This includes Windows-for-Workgroups 3.11, Windows 95, Windows 98, and NT.


Serv-U Registration web site
FTP Serv-U Registration Web site

To register FTP Serv-U, please go to www.ftpserv-u.com/purchase.htm, or contact Deerfield.com at:

Deerfield Communications Inc.

PO Box 851

Gaylord, MI 49735

USA

Phone: +1 (517) 732-8856

Fax: +1 (517) 731-2642

E-mail: Sales@ftpserv-u.com

The FTP Serv-U Web site:  www.ftpserv-u.com


Anti-hammer measures in Serv-U
Anti-hammer measures in FTP Serv-U

Users who try to log in every second or so are said to be "hammering the FTP server. FTP Serv-U can now automatically detect these users and block them for a certain amount of time.  Once blocked the user will not receive any message, just get disconnected immediately upon connection. This is a very efficient and low-overhead operation for the server, and an effective way to block malicious users.


Defining IP access rules
Defining IP rules

There are several places where IP address rules are entered.  For example, FTP Serv-U security features determine if the server will allow or deny access based on the IP address of the client.  When defining these rules, there are special characters that define masks that apply to groups of IP addresses.

There are three special characters: the star '*', question mark '?', and the hyphen '-'.  These wildcards function as follows:

The * (Star) character

A star functions as a wildcard for checking the IP-address. Any name or number will match that section of the rule if it is a star.

For example, say all IP-numbers in a company look like 134.56.34.xxx with 'xxx' being any number. To restrict access to the FTP server to other members of the company only, create an 'allow' rule that looks like this:

Allow:	134.56.34.*

Likewise, if unwanted users have IP-numbers in the range 168.76.xxx.xxx, they can be restricted from a server with a'deny' rule, such as:

Deny:	168.76.*.*

Allow:	*.*.*.*

The 'allow' rule at the end is to allow all people in who passed the first 'deny' rule. Without it no one would be allowed access to the server. Remember, whenever there is even a single access rule users will only be allowed into the server if they qualify for an 'allow' rule.

IP-names may also be used in access rules. IP-name rules work in a similar fashion as IP-numbers. For example, to keep all users from a particular university out of the server, set up the following two rules:

Deny:	*.univerisityx.edu

Allow:	*.*.*.*

The  - (Hyphen) character

The hyphen is used to denote a range of numbers, so that can only be used for IP-numbers. Simply separate the starting and ending values by a hyphen.

For example, assume that users that need access have IP-numbers 134.56.34.128, 134.56.34.129 and 134.56.34.130.  Three 'allow' rules could be defined, each with one of these numbers.  However, a faster way to do this is to make a single 'allow' rule like this:

Allow:	134.56.34.128-130

The special characters '*' and '-' don't need to be at the end of the IP-numbers, any place will do. The rule 221.*.76-154.89 is perfectly OK.

The ? (Question mark) character

The question mark is for IP-names only, to match any single character.

Note when using IP name rules:

There is one more side effect of IP-name rules. When FTP Serv-U starts, it does not know if there are any IP access rules that need an IP-name lookup, and searching all possible rules is prohibitive. Doing a reverse IP-name lookup is computationally slow and can take any amount of time (FTP Serv-U has a hard-coded limit of one minute for this), while the FTP client has to wait until the lookup is done. So, by default it does not do reverse-DNS lookups to determine the IP-name of the FTP clients that connect to the server. This means the first time an IP access rule is encountered that needs an IP-name, the user will be bounced (since no name is available at that point). However, once this happens the server switches strategies and does an IP-name lookup every time a user connects.


Printing via FTP

FTP Serv-U allows access to all PC ports: PRN:, LPT1:, LPT2:, LPT3:, LPT4:, AUX:, COM1:, COM2:, COM3:, and COM4:. This can be a convenient way of setting up a 'network' printer by transferring files directly to PRN: or LPT1: using FTP. These ports are treated like any regular path name, so a user needs access rights to use them. Thus, to make a printer on PRN: accessible and a modem on COM2: the user needs the following access rights in the Setup Users or Setup Groups dialog box:

PRN: - write and delete rights

COM2: - read, write and delete rights

These ports behave very much like files that always exist and can be found in every directory although they do not show up in directory listings. So, no 'change directory' commands are needed, just transfer the file-to-print to the port with the printer. For a command line FTP client this would look like 'put FILE.TXT PRN:' to print file FILE.TXT on a printer attached to port PRN:. For point-and-click type FTP clients, specify that it ask you for the destination file name. Then, when prompted for the destination file name, enter 'PRN:' or another defined port. For example, for the popular client WS_FTP , check the 'Prompt for destinations file names' option in the 'Session Options' section. After doing that, simply upload the file-to-print and it will ask for the destination, for which the printer port name is entered.


One-time password processing

Normally FTP sends all passwords via the network in clear-text. Anyone with a packet sniffer at the right place can see them. OTP (=One Time Passwords) changes this, it never sends a password over the network. Instead, it sends a one-way encrypted version of the password called 'hash' over the net. There is no way known to man to retrieve the original password from this hash, so it is very safe. The same hash value is never used twice. So even if someone intercepts it, replaying will not work (That is where the term "one-time password" comes from).

FTP Serv-U supports a popular form of OTP, called S/KEY that in turn comes in two variants, MD4 and MD5, which is about the hash function it uses and both are supported in FTP Serv-U.  S/KEY can be enabled for individual user accounts via the Miscellaneous user account setup dialog box.  When storing passwords in encrypted form, new passwords must be entered since FTP Serv-U needs to know the password when using S/KEY and the encrypted password stored in the user setup cannot be decrypted.

To use S/KEY a client either needs to support it (One that supports S/KEY is FTP Voyager, see www.ftpvoyager.com), or needs to let you intercept the USER response and manually enter your password at each log in (The command line FTP client will allow this). In the latter case the S/KEY 'calculator' is required. This  program helps calculate a response to FTP Serv-U's challenge. It is named "WinKey" and can be found at ftp://ftp.cat-soft.com/add-ons/winkey/


Exiting Serv-U
Exiting FTP Serv-U

When FTP Serv-U FTP Server shuts down, the server will check for logged in users.  If users are still logged in, the Exit Serv-U dialog will be shown.

Wait until current users log out

If the server should be shut down immediately, then uncheck the Wait until users log out option, and press the OK button.

If the server should exit gracefully, check the Wait until users log out option.  The server will wait until logged-in users log out before shutting down.