Re: how to interpret route command

From: Paul Colquhoun (postmaster_at_andor.dropbear.id.au)
Date: 03/17/05 

Date: Thu, 17 Mar 2005 01:40:02 GMT

On Wed, 16 Mar 2005 18:49:34 -0600, Charles <charles97@dunjas.com> wrote:
| I am trying to understand what this means...
|
| [charles@host ~]$ /sbin/route -n
| Kernel IP routing table
| Destination Gateway Genmask Flags Metric Ref Use Iface
| 192.168.1.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0
| 169.254.0.0 0.0.0.0 255.255.0.0 U 0 0 0 eth0
| 0.0.0.0 192.168.1.1 0.0.0.0 UG 0 0 0 eth0

| [charles@host ~]$
|
| The first number, 192.168.1.0, is not a real address. So how can it be
| a destination for anything.
|
| The 0.0.0.0 for Gateway make no sense
|
| The 169.254.0.0 means absolutely nothing to me. I do not believe
| I have anything associated with that number.
|
| The one number that makes sense is 192.168.1.1. That *IS* my gateway.
|
| Where can I read more about how to interpret the output
| of the route command?

I'm not sure where this is all written down, but here is my stab at it.

Column 1 (Destination) is where you want to get. This needs to be read
in conjunction with column 3 (Genmask). The 0.0.0.0 entry (with mask
0.0.0.0) matches anything and is called the "default" route.

Column 2 (Gateway) is where packets that match Columns 1 & 3 are sent.
An entry of 0.0.0.0 here means that matching packets can be sent directly
to their destination, generally because it is on the same network segment
as the sender. The network will be attached to the interface in Column 8.

Columns 4, 5, 6 & 7 contain information about where the route came from,
what preference it has in case of multiple routes, and how often it has
been used.

I hope this helps. 

-- 
Reverend Paul Colquhoun, ULC.    http://andor.dropbear.id.au/~paulcol
     Asking for technical help in newsgroups?  Read this first:
        http://catb.org/~esr/faqs/smart-questions.html#intro

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