Re: [PLUG] Raising the dead: proc filesystem

["Paul L. Snyder" <plsnyder@drexel.edu>]

Not the question asked, but if you're potentially behind a NAT are are
looking for the external address (as opposed to needing the bound interface
address), then ifconfig.me is a great service. Just do

  $ curl ifconfig.me
  
which will return your external IP without need of further parsing.
They've got an nice little API, as well...visit the page in a regular
browser to see it.

Paul

On Mon, 07 Jan 2013, David Coulson wrote:

> Here is a really simple way:
> 
> # ip ro get 8.8.8.8
> 8.8.8.8 via 10.250.52.1 dev bond0  src 10.250.52.164 
>     cache  mtu 1500 advmss 1460 hoplimit 64
> 
> Assuming 8.8.8.8 is not directly attached or has a more specific route, the IP following 'src' will be the IP address of the interface through which you route to your default gw. awk/sed/cut your way to only the IP.
> 
> 
> On Jan 7, 2013, at 12:56 PM, Sam Gleske wrote:
> 
> > Reference to an original thread "proc filesystem":
> > http://lists.netisland.net/archives/plug/plug-2002-12/msg00478.html
> > 
> > Has anyone found a decent way to do this outside of parsing ifconfig
> > output?  I've done it in a one liner here...
> >
> > http://www.linuxquestions.org/questions/blog/sag47-492023/using-a-script-to-get-your-ip-address-35251/
> > 
> > Yet I've found that most times I'm able to reliably turn to the /proc
> > filesystem for stuff like this.  I'm just curious if anyone has found a
> > decent way to do this since that thread was originally posted.
> > 
> > I wonder if parsing a combination of /proc/net/fib_trie and
> > /proc/net/route would be useful in finding the IP address of the
> > default route (which I would assume be the internet connected IP
> > address).  I found fib_trie by grep -irl my IP address through /proc.
> > Here's some kernel documentation on fib_trie but there's nothing useful
> > about using it for obtaining the IP address of the default route.
> > 
> > http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=blob;f=Documentation/networking/fib_trie.txt;h=0723db7f8495a1a0466ae06cd311c3e72ce24337;hb=HEAD
> > 
> > I look forward to discussing this.
> > 
> > SAM
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