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Old 11-15-2004, 08:15 PM   #1
Registered: Jun 2001
Location: Chicago
Distribution: Mandrake 10.0 Official
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How do I secure an open relay?

I've noticed a lot of network traffic lately on my web server. The logs show the following: - - [15/Nov/2004:13:23:55 -0600] "GET /fm_pxsc.html HTTP/1.0" 404 403 - - [15/Nov/2004:13:24:03 -0600] "GET HTTP/1.0" 404 409 - - [15/Nov/2004:13:24:16 -0600] "HEAD HTTP/1.0" 200 - - - [15/Nov/2004:13:24:24 -0600] "GET\r HTTP/1.1" 404 407 - - [15/Nov/2004:13:24:38 -0600] "GET HTTP/1.0" 404 409 - - [15/Nov/2004:13:24:43 -0600] "GET HTTP/1.0" 200 56 - - [15/Nov/2004:13:24:43 -0600] "GET HTTP/1.0" 200 56

As you can see, some of the entries show 200, or success. I want to configure my firewall (Shorewall), or Apache, to DROP packets requesting documents from other domains. I Googled "Apache Securing Open relay" but found nothing other than links to articles on securing SMTP relays -- which is not the problem. Any ideas?

I hope somebody can help and I thank you for your assistance.

Last edited by lhoff; 11-15-2004 at 08:17 PM.
Old 11-15-2004, 09:02 PM   #2
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Registered: Jul 2003
Location: Silicon Valley, USA
Distribution: OpenBSD 4.6, OS X 10.6.2, CentOS 4 & 5
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What you're talking about is an "open proxy", not an "open relay" (open relay is an e-mail term). Check to make sure making those requests to your site really does fect the content from the other sites. If you have a default vhost it will respond with 200 to everything, but only show the default Apache "under construction" page. You can try it yourself by telnet'ing to your IP on port 80 and issuing the following:
GET / HTTP/1.0
If you get the information from, then you have big problems! You've seriously misconfigured mod_proxy, or perhaps someone has intentionally misconfigured it (for instance they could have exploited your box and quitely turned it into an open proxy).

If you get the default Apache page, that's what is expected.
Old 11-16-2004, 10:48 AM   #3
Registered: Jun 2001
Location: Chicago
Distribution: Mandrake 10.0 Official
Posts: 181

Original Poster
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How would I check that via SSH? (I do not have telnet running on that server.)

I assume the following:
ssh -p 80 192.168.x.x
GET / HTTP/1.0
but that produces no response at all.

If I login to the server's command line (user login, via ssh) and enter
GET / HTTP/1.0
I do get sun output, but I don't think I'm getting it through Apache. So, I'm confused.

Also, this is my proxy directive:
<Proxy *>
   Order Deny,Allow
   Deny from all
ProxyRequests off
Thanks for your assistance!

Last edited by lhoff; 11-16-2004 at 10:51 AM.
Old 11-16-2004, 07:21 PM   #4
Registered: Nov 2004
Distribution: FC1, Gentoo, Mdk 8.1, RH7-8-9, Knoppix, Zuarus rom 3.13
Posts: 98

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No. He's saying use your telnet CLIENT to connect to your http SERVER. http is just plain text after all. Telnet client will talk with it. You don't need a telnet server running. Using a telnet client you can issue commands (well requests) to the apache server that you normally can not do with a stoopid browser.

$ telnet 80

then type the commands.



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