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Wed, 11 Jun 2008

Per-user resolv.conf files

I want per-user resolv.conf files. I've mentioned this in a couple of places and got asked why. It's so that I can have a consistent set of aliases everywhere I go (so I can, eg, type ssh sdf instead of ssh sverige.freeshell.org) and also so that the resolver will fill in my choice of domain on the end of hostnames, so I can be lazy and type ssh plough instead of ssh plough.barnyard.co.uk.

Some quick googling didn't turn up anything usefully cross-platform, but the implementation shouldn't be too hard - just set LD_LIBRARY_PATH or LD_PRELOAD and provide my own resolver library. Unfortunately, the resolver is part of libc so I need to figure out how to:

  • persuade arbitrary binaries to load an extra library;
  • have that library effectively replace bits of libc ...
  • ... even when the functions I'm replacing are called by other functions in libc

Damn, I might have to read about how the linker actually works if I'm ever to do this.

Posted at 19:10 by David Cantrell
keywords: geeky | unix
Permalink | 5 Comments

Funny enough, I was just working on a testcase involving LD_PRELOAD for random $security-weirdness.

Maybe my results are somehow insightful for you...

Posted by Alexander W. Janssen on Wed, 11 Jun 2008 at 21:16:56


Well... If your use is purely SSH (the only examples you give), I do that in .ssh/config:

Host bleh*

HostName bleh.domain.net

User blehuser

Port 1325

etc...

Posted by vegiVamp on Wed, 25 Jun 2008 at 13:47:03


Any updates? I need something like this too.

Posted by Jab~ on Wed, 17 Feb 2010 at 21:27:45


I'm interested too in per-user resolving (less for host aliases but rather for DNS addresses).

I found the following interesting but not implemented so far:

wWw.nickhill.co.uk/resolver_proposal/

Posted by Raph on Sun, 2 Jan 2011 at 14:11:11


But in the host-file case, the following is the answer :

github.com/apetresc/nss-hostslocal

Posted by Raph on Sun, 2 Jan 2011 at 14:19:16


Sorry, this post is too old for you to comment on it.

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