Original destination of transparent proxied connections?
Yeah, I found it.
While researching replacing the 2.2 kernel with 2.4 to get my proxy-oid to work, I stumbled accross the following section in the unofficial NAT-HOWTO (which is not on linuxdoc's website as far as I can tell). At this address:
http://netfilter.kernelnotes.org/unreliable-guides/NAT-HOWTO/NAT-HOWTO.linuxdoc-4.html
Under section four ("quick translation from 2.0 and 2.2 kernels"), under the heading "Hackers may also notice:", item two in the list:
Quoted 3 lines
The (undocumented) `getsockname' hack, which transparent proxy programs could use to find out the real destinations of connections no longer works.
Ah! A clue! But no idea how to make it work under 2.4, and no mention of what replaces it! (I read the rest of the howto carefully. Never mentioned this topic again.) But there IS a way to get it to work under 2.2, if I can learn an undocumented (but functional) hack.
So I jump to the contents page to see who the HOWTO maintainer is to ask rather pointed questions. His email address isn't listed, but I do I find out that the netfilter mailing list is at [email protected]. http://list.samba.org
turns out to have a page of hosted lists, with a link that eventually leads to an archive, which is not easily searchable except by date. Fun.
This brings us to google, which can find anything if you just know what to ask for. I search for "lists.samba.org netfilter getsockname". The first hit is just that silly howto again, but the second hit:
http://lists.samba.org/pipermail/netfilter/2000-September/005317.html
An explanation, complete with example code. From september of last year.
And there was much rejoicing.
If I were to perhaps send linuxdoc.org a check or something, might a day come to pass when learning to do seemingly obvious things under linux does NOT require fairly good forensic investigation skills? I ask merely for information.
I need to get more caffiene now. I'm going to be up REALLY late coding. :)
Rob
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In message <[email protected]> you write:
[ cut 50 lines ]
Quoted 5 lines
If I were to perhaps send linuxdoc.org a check or something, might a day come to pass when learning to do seemingly obvious things under linux does NOT require fairly good forensic investigation skills? I ask merely for information.
And you wonder why my EMail address is not on the HOWTO? Perhaps because there's a netfilter-devel list which can respond far more quickly than I can...
Summary: you had to use a *search engine* to find an obscure piece of coding information.
Shocked!
Rusty.
--
Premature optmztion is rt of all evl. --DK
Quoted 3 lines · --- Rusty Russell
Summary: you had to use a *search engine* to find an obscure piece of
coding information.
Actually, I had to use a search engine to find a tangentially related howto that halfway through mentioned something in passing which gave me a clue of something else to search for that, it turns out, didn't work anyway. (getsockname() in 2.2 returns the original destination ip, but not the original destination port. I had to move to 2.4/netfilter/getsockopt to get that piece of information.)
And the reason I didn't ask on the netfilter list is I was originally trying to use 2.2 ipchains, not 2.4 iptables. Didn't think the old stuff was on-topic there.
Quoted 2 lines
Shocked!
Rusty.
It still requires pretty good forensic investigation skills to make it work...
Quoted 1 line
Premature optmztion is rt of all evl. --DK
Wouldn't that be "Premtur"? :)
Rob
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