[olug] Ping Is Broken

[Rob Townley]

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

ping -I is broken

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* = 4.3.2.8 and the default gateway is accessed through a different
interface eth*1*.
eth*1* = 192.168.168.155 is used as the device to get to the default
gateway.
*FAILS *: ping *-I eth0* 208.67.222.222
*WORKS*: ping *-I 4.3.2.8* 208.67.222.222
*WORKS*: ping *-I eth1* 208.67.222.222
*WORKS*: ping *-I 192.168.168.155* 208.67.222.222

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 208.67.222.222
PING 208.67.222.222 (208.67.222.222) from 4.3.2.8 eth0: 56(84) bytes of data.