CD ROM Paradise Collection 4/CD ROM Paradise Collection 4 1995 Nov.iso/comms_w/ftpsrv10.zip/SERV-U.TXT

Text File | 1995-02-04 | 51KB | 1,142 lines

                         FTP SERV-U


                FTP-Server Daemon for WinSock


                        Version 1.00















                     Made by Rob Beckers

                           Cat Soft

                       4 February 1995





                         DISCLAIMER
                         ==========

I  know, it's not the nicest way to start off. So let's just
get this part over with, OK?!

The  FTP  server  program Serv-U and its  documentation  are
copyright  of  Rob Beckers. It is distributed as  shareware,
giving  you the right to try it for a period of 30 days.  If
you  intend to use Serv-U after the initial try-out  period,
you are obliged to pay the registration fee.
The  next paragraph is a beautiful piece of prose.  In  just
two  sentences  it  says it all. Alas, unfortunately  it  is
necessary, so please bear with me.

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.



CONTENTS
========

Introduction                                               1

1. Making It Work - Installation                           3
  1.1 Installation                                         3
  1.2 De-installation                                      3

2. The Grand Tour - Menus                                  4
  2.1 The File Menu                                        4
  2.2 The Edit Menu                                        4
  2.3 The Setup Menu                                       4
  2.4 The Help Menu                                        9
  2.5 The Logfile and Screen                               9

3. The Inner Workings                                     11
  3.1 Serv-U Internals                                    11
  3.2. The SERV-U.INI File                                11

4. Getting In Touch - Bugs & Registration                 16
  4.1 Reporting Bugs                                      16
  4.2 Registering Serv-U                                  16

Registration Form Serv-U                                  18



INTRODUCTION
============

Thank you for giving this program a try!

With  FTP  Serv-U your PC will be turned into a FTP  server.
This means that others on the computer network that you  are
connected  to  can access your PC to copy, move,  make,  and
delete files and directories, using the FTP protocol (FTP  =
File  Transfer  Protocol). This protocol  dictates  standard
ways  of  communicating  between  computers,  so  that  many
different  types  of  computers, using  different  operating
systems and file formats, can exchange information.
FTP  Serv-U  is a 'server' program and/or daemon.  The  term
daemon  comes from the 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 PC's  running
MS-Windows that have a WinSock version 1.1 compatible TCP/IP
stack installed.

Why  use  this  program and not one of the  many  other  FTP
servers that are available? For this I have to take you back
in time a little, to about a year ago. I needed a FTP server
to  make  some  files available to others and  tried  out  a
number  of server programs. One simply didn't work.  Another
would  work,  but as soon as someone started transferring  a
file from my PC it would lock up the whole machine until the
transfer  was complete. And then there was one  that  worked
fine,  but lacked all but the most basic security. So, after
endless  frustration I decided to write my own, figuring  it
couldn't  be  that hard. As usual things got a  bit  out  of
hand,  but  a year and over 10000 lines of C++ later  you're
looking at the result!
So what has this FTP server to offer?

     * Access for  multiple clients at the same time. Access
       for 'Anonymous' users. With the possibility to  limit
       the  number of clients at any given time, so your  PC
       remains workable.
     * Lots of security! On a directory and even file basis.
       Allowing  different settings for  each  user, and  by
       putting   users   into   'groups'   permitting   easy
       maintenance  for large numbers of users. There's even
       an  option  to allow or prohibit clients on the basis
       of  their IP-number. Ideal if you want to let certain
       people  roam around your computer, but you don't want
       the  whole  world knocking at your door  (that is  to
       say: they can knock, but they won't get in).
     * A  quite  complete  implementation, and  very  strict
       adherence  to the FTP standard (found in document RFC
       959).  Supports the 'passive' command  PASV.  This is
       needed  by WWW-browsers that use proxy agents for FTP
       transfer   (something  required  when   there   is  a
       'firewall').  Another  feature  is  that  'Anonymous'
       users  always  see the root directory ('\')  as their
       login  directory. This, again, is needed by some WWW-
       browsers to make FTP transfers work.
     * Easy to setup and maintain. Everything is  accessible
       through  menus,  and  for  automated  maintenance the
       settings are stored in an .INI file of simple format.
     * It  is fast! The file transfer speed you'll  get will
       be  very  close  to the maximum your TCP/IP  stack is
       capable  of   (well, assuming your FTP  client  is at
       least as fast of course).
     * A very cute icon!
     * Compared to the commercial implementations, Serv-U is
       dirt cheap!

If  you didn't register this program, then you're looking at
the  try-out  version  of  Serv-U.  This  version  is  fully
functional,  there  is  absolutely no  difference  with  the
registered version. But (yes, there had to be a 'but') after
a  little over 30 days it will stop to work. Counting starts
the  first  time you run the program. I warn you beforehand:
re-installing it will not help you!

Before  I  forget  it:  Thanks, Lars,  for  testing  Serv-U,
thanks, Kyle, the best bug buster of all, and thanks,  Brad,
for  turning my attempt at English into the real thing. And,
Alun,  I  hope I didn't shock you too much by bringing  this
program out. You can't say I didn't warn you though . . .

OK,  enough  sales  talk.  Let's continue  with  the  actual
documentation. First thing will be how to install Serv-U  to
get you in business.



1. MAKING IT WORK - INSTALLATION
================================

You're  eager  to get things going, but a little  afraid  of
what  lies  ahead. Never fear, it couldn't  be  simpler.  So
let's get started!


1.1 INSTALLATION

Nothing more simple than to install Serv-U: just unzip it in
the directory of your choice and run it. There is no need to
change your 'PATH' or put anything in other directories.

Serv-U comes with the following files:

     SERV-U.EXE          - The FTP-server executable itself
     SERV-U.DOC          - The   documentation   in  MS-Word
                           format
     SERV-U.TXT          - The documentation in ASCII format
     README.TXT          - Something you have to read
     BWCC.DLL            - The Borland Custom Control library
                           that creates the 3D-look
     REGISTER.TXT        - A registration form in ASCII format

When  Serv-U  is started for the first time, it creates  the
file:

     SERV-U.INI          - File containing  all settings and
                           user information

The  only finer point you might want to pay attention to  is
whether  or not you already have the file BWCC.DLL  in  your
Windows directory. If so, you can delete the one in the Serv-
U  directory, but make sure it is the same version  (compare
the sizes)!

When  you  run Serv-U for the first time there  will  be  no
users  and  access  will be restricted. To  change  this  go
through  the  'Setup'  menu items and put  in  your  heart's
desires.  I  advise you to take a look at the next  chapter,
explaining  the various menus, since the security  setup  is
simple but not totally intuitive (sorry for that, but. . .).

For network use with a single executable shared between many
users  that need their own settings, the program  looks  for
the existence of an environment variable with the name SERV-
U. If this variable exists, it should be set to the path for
SERV-U.INI.  The program will then use this instead  of  the
default program directory.


1.2 DE-INSTALLATION

It  is hard to imagine why, but if for some reason some  day
you  want to get rid of Serv-U then that is just as easy  as
was installing it. Just delete the whole directory where you
put  it,  and that's it! Serv-U does not change  any  system
files and does not place any files in other directories.



2. THE GRAND TOUR - MENUS
=========================

The menus and associated dialog boxes have been designed  to
be  as simple as I could make them while still providing the
needed  features  and flexibility. The next paragraphs  take
you  on a grand tour through all of them. I highly recommend
you to take a closer look at the part about setting up users
and security under 'Setup - Users/Groups'.


2.1 THE FILE MENU

The 'Logging' option can be checked to enable logging of FTP
events  to  a file. If unchecked, logging will be to  screen
only.  This option is only available if a logfile  has  been
specified  under  the  'Setup  -  FTP-Server'  menu  choice.
Changing logging through the 'File - Logging' menu will only
affect  the current session. The changes are not  saved  and
the  next  time you start Serv-U logging will  again  be  as
specified in 'Setup - FTP-Server'.

The other option is 'Exit', guess what that does . . .


2.2 THE EDIT MENU

You'll  find  only  one  option here:  'Copy'.  This  copies
selected text from the Serv-U logscreen to the clipboard.


2.3 THE SETUP MENU

This  is  where the fun starts. Almost everything concerning
the  functioning  of Serv-U can be set through  the  'Setup'
menu.  There  are two exceptions: First, if  you  insist  on
allowing access for a user without a password, and,  second,
if you want to make the Serv-U program invisible; meaning it
will  not show up in the list of the task manager.  In  both
cases you'll have to edit the SERV-U.INI file directly.  For
more  information on how to do this, take  a  look  at   the
'Internals' chapter.

The  dialog  boxes where you can fill in your settings  have
not  been made totally bullet proof. It is entirely possible
to  enter  nonsense in certain items and  the  program  will
accept  it  (like  path names that don't  exist,  etc.).  Of
course,  things  might not work exactly as you're  expecting
them  to, but it should not cause the program to crash.  The
bottom  line  is that it is your responsibility  to  provide
settings that make sense.

Now,  let's  continue  with  the 'Setup'  menu  choices  and
associated dialog boxes.

The 'Setup - FTP-Server' option
-------------------------------
This  menu  choice will lead you to a dialog box  containing
matters  directly related to the workings of the FTP  server
itself.
The  first  item  is 'FTP port number'.  This  is  the  (You
guessed it!) port number that the server will listen on  for
incoming  FTP clients. The default is number 21, but  you're
free  to  fill in anything you want, provided  it  does  not
conflict with other network programs. Of course, the rest of
the  world  expects a FTP server to listen on port  21,  but
changing to another number is one great way of insuring that
only  you  and  some selected friends will know  about  your
server. One fun choice is to set this to port number 23  and
then use a telnet program  to 'telnet' to your own PC.

The  next  item is the 'Maximum number of users'. With  this
you  set  the  maximum number of simultaneous users  at  any
given  moment.  Setting it to 0 will  not  allow  anyone  to
enter, leaving it blank will allow an unlimited number,  or,
more precisely, until the PC runs out of network sockets. If
you  need  your PC for regular work as well as being  a  FTP
server,  it  is  probably wise to set a  maximum  so  normal
operations  will  not be slowed down too  much  by  clients.
Likewise, 'Maximum number of anonymous' limits the number of
'Anonymous' users at any given moment. If 'Maximum number of
users'  is specified, then this will limit the total  number
of  users,  both  regular and anonymous,  even  if  'Maximum
number of anonymous' is set to a larger number.

If you would like to leave your PC wide open for the rest of
the  world  you can uncheck the 'Enable security'  checkbox.
But  beware:  DISABLING SECURITY WILL ALLOW ANYBODY  ON  THE
NETWORK  TO DELETE/CHANGE/COPY EVERYTHING ON YOUR PC!!!  The
only  reason  I put this option in is to make  it  easy  for
people  that have their own local network and don't want  to
mess with users and passwords. By default this option is, of
course, checked.

The next two items deal with logging. The first one, 'Enable
logging  to file' switches writing to a logfile on  or  off.
The  second item, 'Logfile' is meant for entering  the  path
and file name of a file to write all the log messages to. Of
course, logging will only work when a valid logfile name  is
entered.  Log  messages  will always  be  shown  on  screen,
regardless of these settings.

The last item in this dialog box is 'Registration code'.  If
you decide to register this program, I will provide you with
a  registration code. This is a combination of 14 characters
and  it should be entered exactly as provided. Uppercase and
lowercase  should  be  preserved and beware  of  points  and
commas, as they can be part of the code. Once a registration
code  is  entered  Serv-U will continue to  work  after  the
initial 30 day trial period.

The 'Setup - IP-Access' option
------------------------------
This  dialog  box provides the means to restrict  access  to
your FTP server to certain IP-numbers. If  for example,  you
work  at a university and only want your faculty members  to
be able to access the server, then this is a great way to do
it.  In  the  upper left corner of the dialog  box  you  can
choose  which type of rules you want to specify:  'Deny'  or
'Allow' rules. The deny rules decide who should be kept out,
the  allow rules indicate who should be welcomed. THE  ORDER
OF  THE  RULES  IS  IMPORTANT! When a  client  contacts  the
server, the deny rules are looked at FROM TOP TO BOTTOM.  If
no  matching  rule is found, the allow rules are  evaluated,
again  from top to bottom. The first matching rule  applies,
and  evaluation is stopped. If there are no IP-access  rules
everybody can enter the FTP server. As soon as there is  one
rule,  only  those  clients that pass  the  rule  check  are
allowed to enter.

You  can type in a new rule in the 'Rule' edit and then  use
the  'Add' button to add the rule to the list. The  'Remove'
button  will  remove the currently selected  rule  from  the
list.  To  change the order of the rules you have to  select
one  by clicking the mouse on it, and then use the 'Up'  and
'Down' buttons to move it around.

Rules  are  nothing more than IP-numbers or  ranges  of  IP-
numbers. There are two special characters: the star '*'  and
the  hyphen '-'. A star functions as a wildcard for checking
the  number. Any number will match that section of the  rule
if  it  is  a star. The hyphen is used to denote a range  of
numbers. Simply separate the starting and ending values by a
hyphen. For example, say all IP-numbers in your company look
like  134.56.34.xxx with 'xxx' being any  number.  Now,  you
want  to restrict access to your FTP server to other members
of  your  company  only. The way to do it is  to  create  an
'Allow' rule that looks like this:

     134.56.34.*

That's  simple,  isn't it! Likewise, if you  know  that  the
competition has IP-numbers in the range 168.76.xxx.xxx,  you
can keep them out of your server with the 'Deny' rule:

     168.76.*.*

Now,  you  need  to  share some of your  files  with  a  few
collegues,  and management in your company is too  cheap  to
install  a local network. You find out that their PC's  have
IP-numbers  134.56.34.128, 134.56.34.129 and  134.56.34.130.
You  could of course make three 'Allow' rules, each with one
of  these  numbers. A faster way to do this  is  to  make  a
single rule like this:

     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. I wouldn't know  when  you'd  need
this,  but,  hey,  the world is a strange  place!  Remember,
order  is  important  and deny rules  are  always  evaluated
before the allow rules. Experiment a bit, and you'll get the
hang of it.

The 'Setup - Signon/Signoff' option
-----------------------------------
Your  FTP-server can display a welcome message every time  a
user  connects  to  it. This can be very useful  to  provide
users with information about your FTP server, like where  to
find  games, or 'Serious Software'. Likewise, you might want
to  say good-bye to them when they leave, or remind them  to
send  that  check . . . The way to do this is by entering  a
text in the 'Signon/Signoff' dialog box.
There  are  a few special characters that you can  enter  in
your signon/signoff text which get expanded while being sent
to a client. These are:

     %t   - gets expanded to the current time on your PC
     %d   - gets expanded to the current date on your PC
     %u   - turns  into  the  current number of Serv-U users
            logged in

So, you could use the following signon text:

     Welcome, it is %t on %d, and you are user number %u

I'm  sure you'll figure out by yourself what this will  look
like  to  the user . . . If you have ideas for other  useful
special characters, let me know about it!

The 'Setup - Users' option
--------------------------
Unless you switched off all security, you are going to  have
to  set up users. And, you guessed it, this is the place  to
do so!
Upon  choosing this option a dialog box is presented to you.
It  contains  a  list  of all known  users.  To  change  the
settings  for  a certain user, just click on  the  name  and
click 'Edit' (or just double-click on the name). Now, if you
just started this server for the first time there will be no
names,  short  of Divine Intervention. Never mind,  just  go
ahead  and click 'Edit'. You'll be presented with  an  empty
dialog  box  containing  entries for everything  you  always
wanted to set for a user.
The  next thing is important, so pay attention: You can fill
in or change any name in the 'User name' field. If this name
does  not  exist it will be added to the list of  users.  If
this name exists, the settings for this user will be changed
to  the ones in the dialog box. So, if you double-clicked on
user  'James'  and  then  go  on  to  set  his  password  to
Qlightbulb' and you change the user name to another of  your
users, 'Tanya', then Tanya is going to be mighty upset  when
she  tries  to enter your FTP server! James will  of  course
have to remember his old password, since nothing changed for
him.  This  way  of dealing with users might strike  you  as
somewhat  strange. The advantage of it is that you can  take
an  existing user and, by making only the few needed changes
turn it into a new user.

Now  let's take a closer look at the various fields  in  the
'Edit  User'  dialog box. I've dealt with  the  'User  name'
field, so this brings us to 'Group name'. Every user can  be
part  of a group. The convenience in making users part of  a
group is that you can leave common settings for all users of
a particular group blank and just fill them out in the 'Edit
Group'  dialog  box.  This goes for all settings,  including
password, home directory and path access rules. To  overrule
a  certain  group setting, simply provide one for the  user.
For  example,  you're the Pentagon system administrator  and
want to create FTP access for everybody in case they are  on
field trips. So, you hook up this old PC to the net, install
Serv-U  and register it (hypothetical situation).  Then  you
proceed to create a group 'StarWars'. Now you go on  to  set
the  password  for  this group, 'RonaldR',  and  their  home
directory    (all   their   files   are   shared    anyway),
'y:\super\secret\starwars'. You fill  in  some  access  path
rules  as well, and you're all set: The only thing  left  is
entering the user names, you don't have to provide any other
information  per  user.  A 10 minute  job.  Now  there's  an
occasional guest user, 'BillyC'. You don't want him  to  get
into  certain directories, so you make him a member  of  the
group but specify those directories in his access path rules
with 'no access', and you're all done.

We  did  get  ahead  of ourselves in the discussion  of  the
various  fields,  so  let me back up a bit.  The  'Password'
field  shows stars ('*****') when entering a password. Don't
worry, this is only to protect you from prying eyes. Also if
you're  editing an existing user who has a password, nothing
will be shown here, but the password is still there. To keep
the existing password for a user: don't edit this field! The
passwords  are  stored encrypted using  UNIX  'crypt'.  This
algorithm works like a sausage machine: you put in a pig  on
one  side  and  turn the crank, out comes the sausage.  But,
pushing  in  the  sausage while turning the crank  backwards
will  not get you a pig! It is quite secure, I wouldn't know
of  a way to get the plain text password back (the NSA might
though).

The  'Home directory' field is for the user's home directory
(to kick in an open door). This is the place where he or she
is  put immediately after logging in. Each user needs a home
directory,  without one the server will not  permit  logging
in.  Of course, if a user is part of a group, and this group
has a home directory you don't have to specify one here. You
might  want to, if this user needs a different one from  the
rest of the group.

This  brings  us  to the last part of this dialog  box,  the
'File/Directory  access' rule list.  This  list  contains  a
number  of  paths  with access information coupled  to  each
path.  Access to the PC is only allowed according  to  these
paths  and  their  access information. No access  paths,  no
access! So, there is one path you might always want to be in
the list: the user's home directory.
When  a  user  executes a FTP command  concerning  files  or
directories, the user's path list is checked to see  if  the
command  should be allowed to proceed. The list is evaluated
FROM TOP TO BOTTOM! SO THE ORDER OF THE PATH ACCESS RULES IS
IMPORTANT!!!  There  are  five  different  types  of  access
information  that  can be set for each path.  The  first  is
'Read'  access, this allows files to be copied from  the  PC
using  the  FTP  'get'  command.  Next  is  'Write'  access,
allowing files to be copied to the PC using 'put',  but  not
changed,  deleted,  or renamed. Third  is  'Delete'  access,
allowing  the user to change files, rename, or delete  them.
Having  'Delete' access automatically includes write access.
The  last  two items deal with directories. 'Create'  access
lets  the user create new directories at this path. 'Delete'
lets  the  user  delete directories.  To  make  a  directory
listing any one of these rights is sufficient for a path. If
none  of  the  rights have been granted for a certain  path,
then the user has no access what-so-ever to this path.
The rights of a certain path are valid not only for the path
itself, but also for all subdirectories of it. If you  don't
want  this to happen for a certain subdirectory you have  to
specify  this directory with the desired rights  before  its
parent in the list of paths.

Since  one  example can say more than a thousand  words,  or
something  along these lines, let's work through  a  typical
situation. Assume you want to setup an 'Anonymous' FTP site.
This  needs a directory tree with all the goodies the  users
might  want, for which they need read access. You also  need
an  upload directory where users can upload new goodies, but
you  don't  want others to be able to immediately get  their
fingers  on  it, since you want to check for viruses  first.
So, this directory needs write but no read access. We decide
to  put everything on the big network drive, 'Y:', under the
'ANONFTP'  directory. We also create the 'UPLOAD'  directory
here  for  uploads.  In  Serv-U we  would  create  the  user
'Anonymous'  with the following access path  rules  (and  in
this order):

     Y:\ANONFTP\UPLOAD   - write rights
     Y:\ANONFTP          - read rights

Reversing the rules will not work: If a user would write  to
the  upload  directory  the security  mechanism  will  check
against Y:\ANONFTP and conclude that UPLOAD is a subdir,  so
the rule applies, and the rule grants only read access.
If  the  drive letter is left out of a path, it applies  for
all  drives. So, a fast way to get full access to all  files
on all drives is:

      \                  - read, write, delete,  create  dir
                           and delete dir rights

Now,   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. Lets take  the
previous example about the anonymous FTP server. We want  to
put a file 'SECRET' in the ANONFTP directory, but nobody  is
allowed  to  read  it of course. So, our access  paths  list
would look like this:

     Y:\ANONFTP\SECRET   - no rights
     Y:\ANONFTP\UPLOAD   - write rights
     Y:\ANONFTP          - read rights

Again,  the  order of the paths is important! The  directory
access rights do not have any meaning for files.
The  buttons  speak for themselves, so I'll  not  waste  any
bytes on them.

There  are two special user names, although in setting  them
up  they are dealt with exactly the same as any other  user.
These are the user names 'Anonymous' and 'ALL'.
We  already came across 'Anonymous', it allows users to  log
in  without a password. The FTP server asks for their E-mail
address instead and logs this. The 'Password' section in the
'Setup  Users' dialog box is ignored for this user name.  If
an  anonymous user logs in, he will not see the  whole  file
structure.  To him everything will appear to be relative  to
the  home  directory. So, to abuse our previous example  yet
another time: After logging in he will be put in Y:\ANONFTP,
but  if  he asks for the current path the server will answer
'\'. All actions concerning files will, also, be relative to
his  home  directory. The reason for making it this  way  is
that  certain  World  Wide Web browsers  that  log  into  an
anonymous  FTP  server will execute a 'change directory'  to
'\' immediately thereafter. They get mighty confused if this
is  refused, so by making their home directory '\'  this  is
avoided.
The  other  special user name is 'ALL'. Now where does  this
tie  in?  Well,  every action requiring  security  clearance
(checking  a password during login, reading, writing,  etc.)
is  first  checked against the settings for  the  particular
user. If no appropriate setting is found there, and the user
belongs  to  some group, the group settings are checked.  If
still  no corresponding setting is found, the user 'ALL'  is
consulted  (if it exists). So 'ALL' works as a  blanket  for
all  users,  providing the most common settings. Of  course,
this  also provides a potentially big security hole,  so  be
careful!

The 'Setup - Groups'  option
----------------------------
Choosing this presents you with exactly the same dialog  box
as  the 'Setup - Users' section. The only difference is that
you  cannot fill in a user name. Everything works  the  same
way  too,  so I'll let you figure it out. Of course,  you're
not dealing with users here but with group names.


2.4 THE HELP MENU

This  menu choice is still a bit underdeveloped, it has only
the  'About' item. This does however present you with a very
beautiful 'about' box, thus more than making up for the lack
in other areas.


2.5 THE LOGFILE AND SCREEN

Although  they are strictly speaking not part of the  menus,
this  is  a  convenient place to discuss the format  of  the
logfile and screen messages.
Messages  are always logged to the Serv-U window, regardless
of  the logfile settings. There is no difference between the
messages  on  screen and the ones in the  logfile,  although
some  things are only shown on screen. The latter are server
and  program  related matters, like version  number,  server
going on/off-line etc.

Log  messages  always have the same layout. The  reason  for
using  such a strict format is to make it easier  to  search
for  specific  messages or certain types  of  messages.  The
format is as shown below, in stylized form:

     [n] DATE TIME - (xxxx) MESSAGE

The first number, 'n', indicates the type of message that is
being logged. Currently there are five different categories:

     1    - system messages (problems etc.)
     2    - FTP commands (not used yet)
     3    - GET file transfers
     4    - PUT file transfers
     5    - security related events (users logging in etc.)

The  second  number, 'xxxx', is a unique ID  assigned  to  a
client  the  moment  the connection  is  made.  All  further
messages  concerning that client will use the  same  number.
Again,  this  was done to make it easy to find  back  events
using the 'search' facilities of every editor.



3. THE INNER WORKINGS
=====================

Before  I  go on to describe the settings of the  SERV-U.INI
file  I want to spend a few words describing how Serv-U  was
made and how it goes about its job.


3.1 SERV-U INTERNALS

The program was made using Borland C++ version 3.1. To check
for  shaky  pointers and catch all those resource leaks  the
program Bounds Checker version 2.1 from Nu-Mega was used.  I
think  no  serious Windows programmer should be without  the
latter, much recommended!
This  whole  project  started about a year  ago  after  much
disappointment with the existing FTP servers for WinSock. In
its  current version it consists of just a little over 10000
lines  of  C++ code, divided into 16 C++ classes. The  whole
program was constructed from scratch, not using any existing
FTP   server  code,  and  is  tailored  to  MS-Windows   and
WinSock's.
Internally, everything is very much compartmentalized, using
a  different class for different partial tasks. There  is  a
WinSock   class  library,  providing  hi-level   access   to
WinSockets  and hiding all the nasty parts of  dealing  with
them.  It  uses  100% asynchronous WinSock  functions  (also
called 'non-blocking' functions) thus avoiding problems with
multiple active sockets for a single task and re-entry  (let
me  know  if  you're interested in this class  library,  I'm
thinking of selling it in souce code format). There is a FTP-
manager  class,  taking care of listening for  clients,  and
setting  up  instances of the FTP-command interpreter  class
when this happens. The latter does the actual interpretation
of  the  FTP  commands, talking to the  security  class  for
clearance  and  the  WinSock class for communications.  Then
there are some utility-like classes, like those dealing with
setup  and  logging. By having all these  compartments  that
handle  very well defined tasks I hope to be able to  easily
extend  this  FTP  server  and  fix  those  (hopefully  few)
remaining bugs quickly!


3.2 THE SERV-U.INI FILE

All  the  settings, for the server, users,  and  groups  are
stored  in  a  single  file in text  format.  This  file  is
normally   named  SERV-U.INI.  Unless  this   is   otherwise
indicated,  something I'll get to in a  moment,  the  Serv-U
program  looks  for this file in the program  directory.  To
indicated  that  SERV-U.INI  should  be  found  in   another
directory, an environment variable SERV-U should be  set  to
the   desired   path.  This  can  be  useful   for   network
installations that use a single copy of the program but need
separate .INI files.
To  go  over  all the items that can appear in SERV-U.INI  I
will show you an invented setup file:

     [GLOBAL]
     Security=TRUE
     PortNr=23
     MaxNrUsers=5
     MaxNrAnonymous=3
     Invisible=TRUE
     Logfile=c:\serv-u\logfile.txt
     Logging=YES
     Authorization=JK2S%FgdfsdEvG
     Window=100,100,400,300

     [SIGNONOFF]
     SignOn1="Welcome to Robby's FTP-Server!"
     SignOn2="It is %t local time on %d and you are user nr.
     %u"
     SignOff1="Thanks for logging in!"
     SignOff2="Hope to see you again soon . . ."

     [IP-ACCESS]
     Bounce1=132.68.175.201
     Bounce2=223.*.*.*
     Allow1=132.68.176.53
     Allow2=132.68.175.*
     Allow3=101.43.23.30-40

     [USER=Rob]
     HomeDir=c:\
     Password=RdfgSff$#Ffr@#d
     Group=System
     Access1=\,RWDCM

     [USER=Anonymous]
     HomeDir=d:\anonftp
     Access1=d:\anonftp\upload,W
     Access2=d:\anonftp,R

     [USER=ALL]
     HomeDir=y:\
     Access1=y:\,R

     [GROUP=SYSTEM]
     Access1=c:\system,RWDCM
     Access2=d:\,RWDCM
     Access3=y:\novell,RWD

All  but  three  of these settings can be  changed  and  set
interactively through the 'Setup' menus. The exceptions  are
the  entries for 'Invisible' and 'Window', and if you desire
a  user to really have no password the entry 'Password=' has
to be set manually for that user.
The  following  paragraphs will describe  each  section  and
entry in more detail.

[GLOBAL]
All  the settings related to the Serv-U program itself, i.e.
the  functioning of the FTP server and system functions, are
found in the '[Global]' section.
If security should not be enforced, the 'Security' entry can
be  set  to  FALSE or 0. Doing so will leave the FTP  server
wide  open  to everybody!!! Default value for 'Security'  is
TRUE.
The  'PortNr' entry determines the IP port that  the  server
will listen on. Default value is 21.
To  limit  the  maximum  number of  simultaneous  users  the
'MaxNrUsers' entry should be set to the desired  number.  No
entry  or a negative number results in no maximum, only  the
number  of available sockets will limit the number of  users
in  that case. Similarly, the 'MaxNrAnonymous' entry  limits
the  maximum number of 'Anonymous' users. The value put here
is  only  meaningful  if  it is smaller  than  that  of  the
'MaxNrUsers' entry.
For  system  managers that don't want their  users  to  mess
around with the server settings, it is possible to make Serv-
U  invisible by setting the 'Invisible' entry to TRUE, 1  or
YES  and put the Serv-U program in the 'startup' group. When
this is done the server will not show up in the task manager
list.  One consequence is that there is no way to  stop  the
program  short of exiting Windows. Default is  NO  for  this
entry.
The  'LogFile' entry should specify a full path and name for
a  logfile  if  logging  is desired.  There  is  no  default
logfile. To actually switch logging on and off the 'Logging'
entry  can  be set to ON or TRUE, or OFF or FALSE. Switching
logging  ON  will  only work if a logfile is  specified.  By
default 'Logging' is set to ON.
The   'Authorization'  entry  is  used  for   entering   the
registration  code.  You get this code  after  registration.
Default it has no value and for evaluation of the program it
should be left blank.
The  last entry is 'Window' and this is set by Serv-U  every
time  the  program is stopped. It contains the last position
and   size   of   the   program  window,   in   the   format
'top,left,width,height'

[SIGNONOFF]
This  section contains the messages that are displayed after
a   user  contacts  the  FTP  server  and  just  before   he
disconnects. Every line has a separate entry with  a  number
at the end, denoting the order. The signon message is put in
'SignOnxx'  entries  (with  xx the  line  number),  and  the
signoff message is put in 'SignOffxx'.
There are three special character combinations recognized by
Serv-U  and they are expanded to their actual values when  a
user logs on or off. These are:

     %t   = current time
     %d   = current date
     %u   = current number of users that are logged in

A  tip:  Keep  the  number of lines  and  the  their  length
limited.  Most  FTP  clients will  mess  up  lines  over  80
characters,  and  since a FTP reply code is  tagged  to  the
beginning of these lines before they are sent, it is wise to
keep them to less then 75 characters.

[IP-ACCESS]
This  section  determines which client  IP-numbers  will  be
allowed  access  to Serv-U. There are two  kinds  of  rules:
Those  that  refuse access in the form of 'Bounce'  entries,
and  those that grant access using 'Allow' entries. If  this
section  doesn't  exist, or no entries are  found  then  all
clients  are allowed to contact the server. The  reverse  is
also  true,  if  there is even a single entry  ('Bounce'  or
'Allow') then only those clients will be allowed to  contact
the  server  that  pass the rule. All entries  are  numbered
('Allow1',  'Allow2' etc.) and they are evaluated  according
to  their  number  from  first to last.  Numbers  should  be
consecutive.  The  'Bounce' rules are evaluated  before  the
'Allow' rules.

The IP-number of the client is matched section by section to
each  rule until a match is found. If the matching  rule  is
one of the 'Bounce' ones, the client is disconnected. Is  it
an  'Allow' rule then he can proceed. The rules can be exact
IP-numbers, or contain special characters. There are two  of
those:

     *    = wildcard, match any number
     -    = denotes a range

A  quick example: The rule '132.*.76.48-89' will allow entry
to  clients with an IP-address starting with 132, the second
section can be anything (0..255), the third must be  76  and
the  last  section  should  be between  48  and  89  (limits
included).

[USER='Name']
The  information  about a user is stored  in  this  section,
'Name'  stands for the user's name. Each user has a separate
section.  It  contains  items  like  information  needed  to
authenticate a user during login, and rules determining what
this  user  is  allowed to access. The Serv-U  program  will
first  check  this  section  for  a  regular  user.  If   no
applicable information is found and the user is a member  of
a group, the group is addressed for the same information. If
the  result of this is still undetermined, the special  user
name 'ALL' is searched.
Now  to  the entries that can be found in this section.  The
identity  of  a user is verified by comparing his  password,
after encryption, with the one in the 'Password' entry.  The
UNIX  'crypt()' command is used to code the passwords.  This
makes it possible to extract users with their password  from
the  PASSWD file of a UNIX system, the same passwords should
work  on both systems. Unfortunately, there is not a  single
standard for password encryption on UNIX systems these days.
Serv-U uses the most common scheme, but this might not  work
for your system.
If  the  password matches the home directory of the user  is
taken from the 'HomeDir' entry. This should always be a full
path name, including drive letter!
To  make  a  user a member of a certain group,  the  'Group'
entry  can be used. All information needed and not found  in
the  user's  section; password, home dir and  file/directory
access, are then  looked for in the group's section.
Information about file and directory access for  a  user  is
stored  in  the 'Access' entries. Each of these is numbered,
and  access information is checked in order: first comparing
it  to  the  first rule, then the second, etc. The numbering
must  be consecutive. Access rules start with a path or file
name.  These  paths are usually full names, including  drive
letter.  If the drive letter is missing, they apply  to  all
drives. Also, access rules apply not only to the exact path,
but to all subdirectories as well. If different settings are
needed  for a subdirectory, than a rule with that  directory
should  appear before its parent, i.e. with a lesser number.
The  path in an access rule is followed by a comma  and  the
access information itself. This can be a combination  of  up
to five different characters:

     R    = read access to files
     W    = write access to files
     M    = modify access to files (implies write access)
     C    = right to create subdirectories
     D    = right to delete subdirectories

It is entirely possible to have no access information at all
(only  a  path). This means that the user will not have  any
access to that path. For a user to be able to list the files
in  a  directory he needs at least one of these five rights,
any  will do. Another thing to realize is that write  access
to a file does not imply read access! Then finally, the path
in  an access rule does not have to point to a directory. It
is  also possible to specify a filename. Of course, the  'C'
and 'D' rights will not have any meaning then.

There are two special user names: 'Anonymous' and 'ALL'.  If
there  is  an user 'Anonymous', it will be possible  to  log
into the server without a password. Instead, Serv-U will ask
for  the  users  E-mail address and log this.  Most  of  the
regular  entries  apply  for  'Anonymous'  as  well,  except
'Password'  and  'Group', these are ignored.  In  fact,  for
anonymous users the sections for groups and 'ALL' are  never
searched.

The  user 'ALL' is searched if no appropriate rule is  found
in  a user's or his group's entry. It can contain any of the
regular entries.

[GROUP='Name']
These sections contain the group info. The entries here  are
exactly  the  same  as  those for a user,  except  that  the
'Group' entry has no meaning of course.



4. GETTING IN TOUCH - BUGS & REGISTRATION
=========================================

I'd  love to hear from you! Not only for bugs, but  also  if
you  have  ideas, questions, or remarks. Please  drop  me  a
line! The fastest and easiest way to do so is by E-mail.  My
address is:

     [e-mail]

Regular  mail  should work as well, but  might  take  a  bit
longer. My address for this is:

     Rob Beckers
     1911 Erwin Road, Apt. I
     Durham, NC 27705
     U.S.A.


4.1 REPORTING BUGS

Nothing  in  this world is perfect, least of all  me!  Alas,
chances are that despite careful testing you'll still find a
bug.  Please don't think others will report it, let me know!
There  are  a few things I need to know in order to  improve
chances of fixing the beasty, so take note of the following:

   * 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.
   * What TCP/IP and WinSock stack are you using? Brand/type
     and  version number please. Also, what operating system
     (DOS  version  and  Windows  or  Windows-For-Workgroups
     version  x.xx)?  Any memory manager (QEMM  etc.),  what
     version?
   * Please indicate also if this bug is merely cosmetic  or
     of  vital  importance  for using Serv-U.  Somewhere  in
     between  is possible as well of course. By the  way,  I
     consider security related bugs very important!
   * Finally,  please give me a chance to fix a bug,  before
     you  start to shout all over the Internet how bad  this
     program is . . .


4.2 REGISTERING SERV-U

If  you're happy with the performance of Serv-U, then please
make  me  happy and register this program! Just a few  words
for  those  who  are in doubt: Making this program  took  me
(very literally) several months of work, spread out over the
last year. Your registration fee is going to motivate me  to
continue  improving  Serv-U.  In  general,  registration  is
important  for shareware programs: It makes it possible  for
you  to  use  professional  quality  software  for  peanuts.
Lastly, being a biomedical engineering graduate student  I'm
not  exactly  making lots of $$'s (to put  it  mildly).  So,
those 20 bucks for registration mean a lot to me!

To  register,  please fill out the registration  form  below
(There  is  a  separate  one in ASCII  format  in  the  file
REGISTER.TXT.) and send it to me. Payment should be included
with  the registration form, except for Dutch customers,  to
which I'll get in a moment. The registration fee is $20  for
each  copy. Please contact me for site licenses,  I  promise
I'll  not shock you too much! The following forms of payment
are accepted, in order of preference:

     * By check, drawn at an American bank. The check should
       be  made  out  to  Rob Beckers (Alas,  Cat  Soft only
       exists in the mind for now).
     * By  Postal Money Order. As I  understand it, you  can
       buy  these   international  money  orders   in   most
       countries. Payment is in your own currency,  but  the
       money order should be made out for USD $20 and to Rob
       Beckers.
     * Cash, but only in US dollars and I give no guaranties
       about  safe arrival!  Please DO  NOT  send  me  other
       currencies, it would probably cost me  much  more  to
       convert  them  to $$'s than it costs you. A  trick  I
       found  useful for sending cash in envelopes: put  the
       money  in a folded sheet of paper so it doesn't shine
       through   the  envelope.  This  improves  chances  of
       arrival considerably.

Now for the Dutch:
Daar  ik nog steeds een Nederlandse girorekening heb is  het
mogelijk op die wijze te betalen. De prijs bedraagt f. 35,--
per  kopie.  Dit dient overgemaakt te worden op girorekening
53.95.461 ten name van Rob Beckers, te Bunde. Vermeld s.v.p.
'Registratie  Serv-U' zodat duidelijk  is  waarvoor  betaald
wordt. A.u.b. geen geld vanuit het buitenland overmaken! Van
die   35  blijft  zou  dan  heel  weinig  overblijven.   Het
registratieformulier gewoon naar de VS sturen  (post  of  E-
mail).

Next, what do you get if you register? As soon as I get your
registration  I'll send you a registration code.  This  will
enable you to use the program, even after the 30 day try-out
period.  Please let me know your E-mail address,  so  I  can
notify  you fast. In case I have your E-mail address  you'll
also  get  notified when there are updates. Once  registered
you'll get those updates for free, that is: you can use  the
same  registration code on the updates, but you'll  have  to
get  them yourself. Apart from all this you'll also get  the
nice,  warm  feeling of having contributed to  improving  my
financial status!

The   next  page  is  the  registration  form.   Since   the
registration code is tied to the IP-number of the  PC  where
you  want  to use Serv-U, it is imperative that you  provide
this!

************************************************************


ROB BECKERS
1911 Erwin Road, Apt I
Durham, NC 27705
U.S.A.




                    REGISTRATION FORM SERV-U
                    ========================



           NAME: ...........................................

   COMPANY NAME: ...........................................

        ADDRESS: ...........................................

                 ...........................................

                 ...........................................

   PHONE NUMBER: ...........................................

 E-MAIL ADDRESS: ...........................................
                          (Internet only please)
   IP-NUMBER PC: ................. SLIP/PPP? ...............
                 (one for each copy of Serv-U)   (yes/no)
                 ...........................................

                 ...........................................




Registration fee is $20 per copy. Send this order form along
with  your  payment  to:  Rob Beckers, Erwin  Road  Apt.  I,
Durham NC 27705, USA.

If   you  have any questions, comments or suggestions please
contact   Rob  Beckers  at  the  above  address  or   e-mail
[e-mail]. Site license prices  are  given on
request.

As  this software is shareware it comes 'as is', there is no
warranty  implied  or  otherwise, nor is  support  provided.
However, if you discover any bugs or problems please contact
the developer at the above e-mail address.