[olug] Ping Is Broken

Aric Aasgaard aric at omahax.com
Sun Oct 11 01:17:42 UTC 2009

traceroute -i eth0 -I
using ICMP

or using UDP 
traceroute -i eth0


-----Original Message-----
From: olug-bounces at olug.org [mailto:olug-bounces at olug.org] On Behalf Of Rob
Sent: Friday, October 09, 2009 11:45 AM
To: netdev at vger.kernel.org
Cc: CentOS mailing list; Omaha Linux User Group
Subject: Re: [olug] Ping Is Broken

ping -I is broken

The following deals with bug in ping that made it very difficult to set up a
system with two gateways.

Demonstration that *ping -I is broken*. When specifying the source
interface using -I with an *ethX* alias and that interface is not the
default gateway
interface, then ping fails. When specifying the interface as an ip address,
ping works. Search for "Destination Host Unreachable" to find the bug.

eth*0* = and the default gateway is accessed through a different
interface eth*1*.
eth*1* = is used as the device to get to the default
*FAILS *: ping *-I eth0*
*WORKS*: ping *-I*
*WORKS*: ping *-I eth1*
*WORKS*: ping *-I*

The following are actual results which can be reproduced from an up-to-date
Fedora 11 or CentOS 5.3 box. Caused a very very long episode of frustration
when setting up multi gatewayed systems.

* ping using eth0 *:

ping -c 2 -B -I  eth0
PING ( from eth0: 56(84) bytes of

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