On 04/30/2009 10:04 AM, Hellman, Matthew wrote: > I believe that the original poster is trying to deal with the problem of not > having the true source IP address for a given IDS alarm specifically because > of a forwarding proxy or NAT device on his own network. > As I was the original chap back in 2004 who asked this question, I'd like to have my 2c worth too :-)
Indeed the issue was that our (snort) IDS was picking up spyware-infected PCs phoning home through our proxies - and so the IDS could only tell you the src IP was the proxy - no use at all in itself. FYI our proxies lie inside our network - not on the edge (where the IDS are). Well now it's 2009 and we found a different way around it. We installed snort onto all our proxies :-) Now snort can see the clients. As far as the X-Forwarded-For comments go - I think that track is a very bad idea. Everyone running proxies should be taking the opportunity to ensure that header (and its cousin "Via") is stripped out before such HTTP requests leave the site - there's no point in giving away internal IP address information to random web sites. So - on our network at least - using X-Forwarded-For wouldn't be an option anyway. -- Cheers Jason Haar Information Security Manager, Trimble Navigation Ltd. Phone: +64 3 9635 377 Fax: +64 3 9635 417 PGP Fingerprint: 7A2E 0407 C9A6 CAF6 2B9F 8422 C063 5EBB FE1D 66D1
