Frequently Asked Questions (FAQ)

1. Who is Xenu?

Do you want to be a Knight of Xenu? Then join that team in the worldwide RC5-64 key decryption effort, which uses "idle time" on thousands of computers all around the world. Here is how to do it:

Download the client.
Configure the client:
1. Chose "1" ("General Client Options"), then choose "1" ("Your e-mail address") and enter your e-mail address (without "<" or "(" ), then go back to the main menu with "0".
2. Chose "2" ("Buffer and Buffer Update Options"), then chose "9" ("Load-work precedence"), then press the backspace key to delete everything, and enter "RC5,DES=0,CSC=0,OGR=0".
3. If you are behind a firewall, or use a dial-up line, you will have to chose "6" ("Keyserver <=> Client connectivity options") to configure the use of a proxy, or to watch for an dial-up active connection. Go back to the main menu by entering "0" twice.
4. Enter "0" to save the settings and exit.
Start the client and watch him work.

After one day or two, you can go the main statistics page and enter your e-mail address. You can then access your very own statistics page. Scroll down and click "Please e-mail me my password". You will receive an e-mail with your ID and your password. Now click here to join team #3504 and enter ID and password when requested.

Please do not participate in this project if you are on a corporate machine without first getting permission from your supervisor and the security people.

E-mail me if you have any problems with RC5-64. But read the description above first.

2. Is Xenu's Link Sleuth™ better than WebAnalyzer?

Yes and No. Xenu's Link Sleuth™ does not have the graphic capabilities of WebAnalyzer 2.0 ("Wavefront view"). But here are some of the advantages of Xenu's Link Sleuth™:

It is free
Simple user-interface
Better error reports (not just "network error")
"Save" works also while the software is busy
The "broken links view" shows only broken links; In WebAnalyzer you'd haveto press the button again and again as the window fills with crap.
While Xenu does not offer an "update" facility (which doesn't work anyway), it has a "recheck broken links" function that works fine.
It is small, written by one person with 5 years experience of Windows development and 15 years of professional experience as software developer. This means that bugs will be corrected quickly. This is a matter of honour.
The report can be viewed easily, even when you have long URLs.
Uses much less disk space for intermediate files, executable file much smaller
Loading of saved files much faster (WebAnalyzer loses time by displaying the extra graphics)
Supports SSL websites ("https:// ")
Partial testing of ftp and gopher sites
Search for local orphan files
Special handling of redirected URLs
Site Map
Randomization of checking order, means less concurrent requests on a single server

Xenu sez: check your website both with this product and with another product (Linkbot, InfoLink, LinkScan, LinkAlarmand Web Link Validator offer trial versions - WebAnalyzer is no longer available since February 2002 and hasn't been updated for years), and decide what you need and what you are willing to pay.

3. Is Xenu's Link Sleuth™ better than Net Mechanic?

Years ago, Net Mechanic was a free WWW based service, and was useful to check very small web sites. It is no longer free. The free trial is too small, and reports about all links, instead just the broken ones.

4. Can I support the author financially?

No need to. If you feel the software is useful, you may donate money to causes I support.

International Cultic Studies Association (ICSA) is a nonprofit, tax-exempt research center and educational organization founded in 1979. ICSA's mission is to study psychological manipulation and cultic groups, to educate the public and professionals, and to assist those who have been adversely affected by a cult-related experience. I suggest a donation of $20 for individuals and $200 for corporations. In the US, your donation can be deducted from your income. (ICSA does not endorse this site in any way, did not develop this software, does not sell this software, and the use of this software does not depend whether or not you make a donation.)

Germans can make a tax deductible donation to the Dialog Zentrum Berlin e.V., Konto-Nr. 1551390051, Bank fⁿr Kirche und Diakonie BLZ 35060190.

Or visit the Xenu bookstore.

Or send me a T-Shirt of your city, university, employer in XL size. Please don't send anything that is more expensive than $40 (including shipping). Take into consideration that I'll be wearing your T-Shirt at work. USPS "airmail letter post" is fast, reliable and unexpensive (and large sizes are allowed!), so please don't use FedEx or UPS, because this could result in me having to pay money for customs.

Or send me a "thank you" letter on company paper, if you work for a well-known company. Make sure that you are authorized to send such a letter. This is my street address:

Tilman Hausherr
Hauptstrasse 15
10827 Berlin
Germany

5. Why does Xenu's Link Sleuth™ report `http://www.site.com/../page/index.html` as broken?

The key is the "../" part. It means you have e.g. a top level page that links to a page in a directory above, which doesn't exist. It is true that Mozilla will not have any problems with such a page; but I am less tolerant.

6.How can I configure a proxy?

You can configure a proxy in the control application of Windows. Double-Click on the "internet" symbol, then click on the "card" of the dialog box that is named "Connection". You may need a proxy if you are sitting "behind a firewall". This is usually so in big corporate networks.

One user with Windows 2000 always had a timeout, he solved it by checking "Use HTTP 1.1" and also "Use HTTP 1.1 through proxy connections" in the "Advanced" tab of the Internet Options in the control panel. However, this may not work for everyone, because some web servers do not support HTTP 1.1.

7. Why does Xenu's Link Sleuth™ report an URL with a space in it?

Either because you do have a space in the URL, or because you have a carriage return / newline in it. Although Mozilla tolerates this, I do not.

8. I use Mozilla 3.0 Gold and can't get rid of `file:` URLs for images. What can I do?

Re-edit the page, double-click on the picture, remove file: from the picture location and take care to uncheck "copy image to document's location" in the "properties" dialog box (at the bottom left) before you save and exit the dialog box.

9. What is the maximum number of websites that can be checked?

There is no maximum. It is limited by the memory on your computer.

10. Can the software check my site locally?

Since september 1998 (1.0n), you can do so without a local web server (your address would then be http://127.0.0.1). Use the "Browse" button in the "New" dialog box.

The results will not always be the same as a "remote" check:

Sometimes you'll get "error 3". It happens because the WININET.DLL is unable to handle directories, i.e. links that end with "/". You can avoid this by linking to the actual "main file", usually index.html or default.html. That your browser can handle local directories and display them nicely, is because he does additional work, which I do not.
Mixups of higher/lower case characters in links won't be found, since Windows does not make a difference. But UNIX does!/li>
The main reason that you still need to make occasional "remote" checks is because you might have forgotten to upload your files to your WWW server.

A user of IE 4.0 reported that when not online, the software checks every "remote" URL like a local file. This is a problem of the newer version of the WININET.DLL; the version with IE 3.0 reports "no connection" or "no such host" instead, which is more logical.

11. Does it work on Windows NT 3.51?

One user said it worked fine after he copied a version of WININET.DLL from a Windows 95 system standing nearby, and put it into the directory where Xenu's Link Sleuth™ was installed.

12. How is it so damn fast?

Because it uses a (possibly patented, see patents here and here) technique known as preemptive multithreading. It means that the link checking software retrieves several web pages at the same time; the competition uses the same technique. The maximum count of threads is initially set to 30, but you can configure it to any number between 1 and 100. A number that is too high might result in failed connections or in timeouts, which means you will have to recheck the broken links. At the time I had a dial-up connection, I got good results with 70. Now I have a DSL connection, and I have to set the number to 1-5. I suspect that my DSL provider has installed a brake somewhere to prevent "commercial" customers from using the unexpensive "private" service.

13. Can I have the source code?

Hahahahahaha!

14. Can I buy the source code?

Sure, make me "an offer I can't refuse".

15. Just for fun, I checked Tilman's web site, and found many broken links. Why?

I check my own web site every week on friday. Nevertheless there are always broken links:

Links that I know to be broken: I keep them like that to remind me to find these people some day. The web page itself has a notice that the link is broken.
Temporary unreachable hosts: these are temporary routing errors.
Really broken links: I will usually correct the link or remove it within the next few days.

16. How do I correct broken links?

Repairing broken links (i.e. getting the correct ones) is a difficult task that takes time, but with experience, you'll get it done faster and faster.

if you have the e-mail address of the site owner (because you know him), try an e-mail. Sometimes the address still works, even if the web site is gone.
find the home page of the site you link to, to see if the site has a "sorry we moved" message. If you linked to http://www.host.com/~user/page888.html and this is broken, look at http://www.host.com/~user/ to see if there is a message, or to see if the site has been reorganized. Some sites reorganize their user pages differently, e.g. http://www.host.com/homepages/users/page888.html. Sometimes the web switches changes between the two methods. Other sites are owned by the user himself, e.g. www.user.com, so the home page is the root page. If the site exists but you cannot find your page, send an e-mail to the owner.
use search engines to find the site or the name of the site owner (if you know). To find where the site is, use web search engines (like Google or the Internet Archive) and usenet search engines (like Google Groups).

You find the site you searched for
You find a site that links to the site you searched for
You find the site in the Google Cache or the Internet Archive (simply enter the URL in the search box!), and can use the contents to search for the name of the owner
You find a site that links to the site you searched for, but is also broken. E-mail the site owner, and tell him that the link is broken. Bookmark the site and revisit it in a week, to see if the other person has found it. If not, you have nevertheless succeeded in making the other person feel as bad as you, which brings some relief :-)
You find the new e-mail address of the user. Either e-mail him, or try to construct the URL yourself (user@host.com leads to http://www.host.com/~user/)

post a message in a newsgroup that deals with the topic. Hopefully the site owner or one of his friends reads the messages there.
if you are still unsuccessful, either delete your link to the site or repeat your attempts after a month (some sites might reappear in a search engine after some time). Sometimes it happens that a host is reorganizing its hard disk, and all user pages get back within a few days.

17. What about ftp and gopher sites?

Starting with version 1.0k I have implemented a new ftp checking method that is 100% reliable. Sadly, this method does not work with proxies. The previous method I used (and still use for gopher) was unreliable, as it did not detect certain errors.

The method for checking gopher sites is still unreliable. When an ftp or gopher site is accessed through a proxy, this proxy builds up a web page. Sadly, it doesn't always bring up the information whether the URL exists or not. When you access a gopher site without a proxy, it brings an error message, but not an error code. This seems to be a bug of the OpenURL() function of WININET.DLL.

The output lists ftp and gopher sites as links, which allows you to make a manual check of these sites.

18. Why can't I launch URLs?

Starting with version 1.0g (Christmas 1997), URLs are launched with DDE ("dynamic data exchange", a windows method of communication between applications), to open many browser windows but to prevent the opening of several Netscape applications. This is done with the help of the Registry, by searching for HKEY_CLASSES_ROOT\http\shell\open. This has the path for the browser, the DDE application name (e.g. "Netscape"), the DDE topic (usually "WWW_OpenURL"), and a template for the DDE item (usually "%1"). If you cannot launch an URL, do not panic - export and e-mail me the segment of your registry (start REGEDIT.EXE, and search for "http").

The cause is usually that you have not installed Netscape properly (maybe you just transferred the files from another computer). Solution: reinstall Netscape over your current installation.

Starting with version 1.1b, I have stopped displaying an error message when the registry is incomplete, because there were too many complaints. Instead, the browser will simply be launched with the page. This has the disadvantage that the page won't be displayed in an extra window of the current active browser application.

One user with Microsoft Vista 64 (UAC disabled) was unable to launch URLs (message box: "Unable to open browser for 'URL': error 5: Access is denied"). The cause was COMODO Firewall Pro 3.0.25.378. Without the firewall, it worked fine. Please remember that "Personal Firewalls" are mostly snake-oil. Set up am external firewall box instead - this is usually included in your router.

18a. Why does the browser not open a new window?

This is a problem with Microsoft Internet Explorer. Open your registry and search for HKEY_CLASSES_ROOT\http\shell\open\ddeexec. If the key value is "%1",,-1,0,,,, then change it to "%1",,0,0,,,, (i.e. you change the -1 to 0).

18b. Why does Link Sleuth freeze when launching the report?

If Link Sleuth freezes when launching the report, but not when double-clicking on a URL, the reason might be the site map. A site map can be HUGE if the site goes very "deep" (high level, see the "level" column in the Link Sleuth window). A very "deep" site can happen if you have a forum.

Solution: disable the site map in the options dialog, or exclude the "deep" parts of your website (e.g. a forum) in the initial dialog box.

18c. Why does Link Sleuth freeze when launching the report or a URL?

I do not know why this happens, but I have experienced this myself with Windows ME (but not with Windows XP), and have received similar reports from users. The problem goes away by rebooting Windows, but comes back later. You can also get rid of the problem by making a change in the XENU.INI file below the line with [Options], enter this:
UseDDE=0
The only disadvantage is that it will not open a new window in the browser.

19. What about cookies

By default, cookies are disabled, and Xenu rejects all cookies.

If you need cookies because

you have used Internet Explorer to authenticate yourself before starting a run
to prevent the server to deliver URLs with new session id's

then you can enable the cookies in the advanced options dialog.
(This has been available since Version 1.2g)

Warning:
You should not use this option if you have links that delete data, e.g. a database or a shop - you are risking data loss!!!

20. Why are some links reported as "broken" by Xenu, that can be displayed within my browser?

Some servers read the "User Agent", i.e. the name of the software that tries to access a website. Some websites are programmed only for Netscape and Internet Explorer, and refuse everything else. Some may even specifically refuse Xenu because of past misuse. Andi has a list of websites that deny access to Xenu. A user-configurable "User Agent" would be the solution, but this would make abuse possible.

21. Why can't I connect to "secure" (https) sites ?

If you have set your proxy correctly, try to connect with IE. If this doesn't work, read this usenet post for help. If this still doesn't work and you use Windows NT 4.0, install the latest NT service packs (up to SP5).

22. Any known problems with Windows 95?

Some people have reported crashes. These problems were usually solved by installing IE 3.0 (or higher) or the following service packs:

Windows 95 Kernel 32 Update (29.7.1997)
Windows Socket 2 Update (19.2.1998)
Microsoft DUN 1.3 and Winsock2 Year 2000 Update
Patch for "File Access URL" Vulnerability (12.11.1999)
Microsoft DUN 1.4

One guy had problems with the WININET.DLL (v. 4.70.1300) installed with OEM Windows 95 (v. 95 4.00.950 C). Changing to version 4.70.1335 solved the problem.

A simpler solution is to go to http://windowsupdate.microsoft.com and install whatever they tell you (you need to have IE 4.0 or higher on your system)

23. Any known problems with Windows 2000?

Although I received many reports that it runs fine, one user reported a problem and a solution:

Windows 2000 automatically sets a configuration option to use HTTP 1.1 for connecting to web sites. Many, many web sites do not use that version but continue to use HTTP 1.0, so the automatic setting may prevent connections. This is the reason why Xenu would not run for me. When I disabled that setting, Xenu performed properly.

To disable that setting: Control Panel -> Internet Options -> Advanced (tab) -> HTTP 1.1 settings (list heading) -> Use HTTP 1.1 (checkbox: uncheck it)

24. Can I configure the timeout?

Enter the number of seconds in the [Options] segment in XENU.INI, e.g. as timeout=120. The default value is 60. Note that this isn't "perfect". Microsoft Windows has a bugso that the timeout can't be set the way it should. I am using a workaround advice from Microsoft. However I have observed that it doesn't work if the timeout "hits" while trying to find out if a host name exists.

Alternatively, try this:

Start the Registry Editor (REGEDIT.EXE)
Go to HKEY_CURRENT_USER \ Software \ Microsoft \ Windows \ CurrentVersion \ InternetSettings
Select New > DWORD from the Edit menu
Call it ReceiveTimeout with a value of <number of seconds >*1000

Restart your system

Some users have complained that if one URL hits a timeout or a failed connection, all URLs from that host also do. Starting with version 1.2h, this behaviour can be disabled by unchecking "fail all URLs with same failed host" in the advanced options dialog. (The default behaviour is "checked")

25. What about JavaScript?

JavaScript is a programming language, not a formatting language. This makes web pages dynamic; they might depend on the mouse type, the screen size, etc... I have been begged to check simple JavaScript links that have the form javascript:function('address',param1,param2,...,paramN)

My solution, which was first announced in the user group, requires a change in the XENU.INI file. You need a basic understanding of regular expressions (regexp). You must put your regexp in the INI file, like this:

[Options]
Javascript=javascript:.*\(['"](.*(/|s?html?|gif|jpe?g|png|jsp|cfm|zip|exe|aspx?|pl|pdf|xml|ra|asx|ram|swf|php)(\?.*)?)['"](.*)

In the example above, the substring within the first (....) must contain the valid URL.

Frank Visser suggested an improved regexp:

[Options]
Javascript=[j|J]avascript:[_a-zA-Z0-9]+ *\( *['"]([^'"]+)['"]

Frank Visser has also written a better description on his site.

Note: there may be no blank between within "javascript:function", because the regexp wouldn't work.

26. What about passwords entered in a FORM?

The software is not able to enter passwords in a FORM. I just don't see a way to acomplish this easily. I assume it is possible if one combines a set of variable names, values, and a web page that would accept them with a POST command. But some alternatives might work:

Log in with Internet Explorer, start Xenu, then enable cookies in the advanced options dialog (read the details), then start the check
If the server accepts authentication with GET (should work with the Tomcat server), try sending such a URL. However, you might still have to activate cookies.

27. How about a WAP version?

Xenu does check .wml files since February 2001.

28. What about these error codes?

I identify only a subset of all possible error codes in the "Status" column. If you get an unknown error code in the Xenu application window, you can scroll to the right for an explanation text.

More information:

HTTP status codes (100 through 505)
WinInet error codes (12001 through 12156), also here

29. Why do I get broken links with `filelist.xml`, `editdata.mso` and `oledata.mso`?

Because Microsoft creates these broken links :-( Don't bother with them, or read Knowledge Base article Q219694: Saving Office HTML File to a FrontPage Web Results in a Broken Hyperlink. Or try this tool: Office 2000 HTML Filter 2.0

You can also get rid of the problem by excluding them in the advanced options dialog.
Xenu will exclude URLs that end with /filelist.xml, /editdata.mso and /oledata.mso. (This feature has been available since Version 1.2g)

30. Why do I get "file not found" on remote checks?

There may be several causes for this:

Your Internet Explorer isn't working properly, or is in offline mode, or is blocked by your firewall. Enter the URL you want to check into IE and see if it works.
One user got it working by starting Internet Explorer first, and then starting Xenu. I believe that the cause is a broken setup of Windows, or of Internet Explorer.
Your temporary directory is full: enter %TEMP% (not "c:\temp" !) into the Windows Explorer, check if there are many TGH*.* files, and delete them.

31. Can I make a foreign language version?

No, please don't. There's no guarantee that any of the message texts will be kept in the next version. The other problem is that I didn't write the software in a way to be language-independent. I could have done it - but I think most people on the web do understand english.

32. Why isn't Xenu detecting missing URLs?

A web server should return HTTP error 404 for non-existant URLs. Some servers are poorly configured: some redirect to an existing URL with an error message (bad!), others do show an error page, but the server doesn't return the 404 error (very bad!).

One user had the problem that his Microsoft IIS server didn't return the 404 error. He found help on this page, and then sent me his solution, which only works in .ASP under IIS:

	<%@LANGUAGE="VBScript"%>
	<% Response.Status = "404 Not Found"
	On Error Resume Next 'important in an error page to prevent another error
	strTarget = Request.ServerVariables("QUERY_STRING")
	strReferer = Request.ServerVariables("HTTP_REFERER") %>
	<HTML><BODY>The page doesn't exist, sorry dude!<BR></BODY></HTML>

The Apache web server has a different (and better) method of doing the same thing using native HTML code for the webpage. You simply set the correct config items in the http.conf file on your box.

33. Running Xenu with Norton Internet Security

A user had trouble to use Xenu with Norton Internet Security 7, and got error 12007 (no such host). After he added Xenu, it worked. This is what he did:

added Xenu by opening Norton Internet Security by double clicking the Norton "Globe" Icon
In right side panel, "Personal Firewall", Click CONFIGURE
In the Personal Firewall pop-up, Click PROGRAMS
In PROGRAM CONTROLS MENU
- Settings for - "Home (Active)"
- click "Turn on Automatic Program Control" box
- Under "Manual Program Controls"
- Scroll to "Xenu.exe"
- Click Xenu once to Highlight it
- Click MODIFY
in the pop-up:
- Click PERMIT
- Click OK
- Click Ok again
Run Xenu

34. Why timeouts?

This is difficult to answer. The cause might be network overload; it might help to set a lower amount of threads, or to fine-tune the DoS detection of your firewall.

Check your firewall logs to see whether it detected a "SYN flood" DoS attack by you. SYN is the first data packet that is sent to a host when starting a connection. Theoretically, Xenu might send up to 100 SYN packets that are not immediately answered, so a firewall (that counts "unanswered" SYN packets) might think something "evil" is going on. My firewall box once claimed to have detected a SYN flood when I opened many newspaper articles in background browser windows.

35. Any Spyware, Adware, Malware?

This software exists since 1997 and never had any type of malware. It does not "phone home" or return any statistics to me. There are random "ads" in the HTML report for causes I support; however I don't get paid for this. Any passwords that you enter in the software (e.g. for orphan search) are not "remembered" after you close Xenu, nor are they passed to me.

Some debug output is stored in the file XENULOG.TXT which you will find in your %TEMP% directory. That file does not contain any passwords and it is used for support (I will sometimes ask you to attach it to an e-mail to me), primarly for problems with the launch of URLs in your browser (especially the report). The file is human-readable, so feel free to have a look. The file is not sent to me by Xenu, it just sits there and you can delete it if you wish.

Here's a green review by McAfee Siteadvisor about Xenu's Link Sleuth. Note that until before July 11 2008, Yahoo Search (which uses input from McAfee SiteAdvisor) was redflagging every URL of the whole snafu.de domain, including my user site (this seems to have been corrected now). McAfee SiteAdvisor has redflagged the snafu.de domain, but not the user pages. This was related to three downloads (CuteFTP, GoZilla and Nok2Phone) on the customer support ftp site of snafu.de, who has been my ISP for over a decade. These downloads have been removed since then and both Yahoo and McAfee have been notified. On July 30 2008, I noticed that the snafu.de domain has been greenflagged.

If you have any more questions about security, don't hesitate to contact me.