11001: host not found - What..... it was there earlier?

So heres the deal. You have clients behind ISA 2004, trying to browse to a redirecting website. The site starts with an http connection, the user is prompted to logon, or the site redirects to a more secure connection <https>. The interesting thing is that it worked BEFORE installing ISA 2004 Service Pack 2. Hmmmmmmm.

When trying to connect to the https portion of the site various errors are returned:

• 400 bad request.
• 11001: host not found.
• https://%20 example .comom

Why is this happening?

It appears the problem is caused because ISA will add spaces between some headers and their values. If this happens some webservers see the space as the beginning of the hostname. The server then redirects the browser to a website that begins with a space that fails. The browser then fails because it cannot access the malformed URL.

How do I fix this?  

1. Open ISA Server Management
2. Configuration
3. Add-Ins
4. Web Filters
5. Properties of the "Compression filter" - Uncheck "Enable this filter"
6. Properties of the "Caching compressed content filter" - Uncheck "Enable this filter"
7. Select Apply at the top of the screen to apply the changes.

 

>edwalt

Comments

• Anonymous
  September 07, 2006
  Buddy, seriously, thank you so much for this information, it helped me heaps.  I had a similar error which I had troubleshot for a day and had eventually gained enough info to find this page, and your advice fixed the problem.  
  
  Same thing, prob appeared after SP2, but I had different error messages.  Was causing alot of frustration and I couldn't find help anywhere.  ISA logs weren't providing useful data either :o/  
  
  Cheers mate!
  
  Jason - AU

• Anonymous
  February 29, 2008
  vRH8of r u crazzy? I told u! I can't read!

• Anonymous
  February 29, 2008
  smO1hF r u crazzy? I told u! I can't read!

• Anonymous
  February 29, 2008
  ftytUb r u crazzy? I told u! I can't read!

• Anonymous
  March 01, 2008
  VYf1dI r u crazzy? I told u! I can't read!

• Anonymous
  March 06, 2008
  QQW3qq r u crazzy? I told u! I can't read, man!

• Anonymous
  March 06, 2008
  GO69py r u crazzy? I told u! I can't read!

• Anonymous
  March 07, 2008
  p3ewJy r u crazzy? I told u! I can't read!

• Anonymous
  March 07, 2008
  IZ81HK r u crazzy? I told u! I can't read!

• Anonymous
  March 07, 2008
  RkVchS r u crazzy? I told u! I can't read!

• Anonymous
  March 08, 2008
  Gg96Qk r u crazzy? I told u! I can't read!

• Anonymous
  March 08, 2008
  X7W0JT r u crazzy? I told u! I can't read!

• Anonymous
  March 08, 2008
  O3rZh6 r u crazzy? I told u! I can't read!

• Anonymous
  December 07, 2009
  The comment has been removed