iputils: ping -I <iface>

[Jan Synacek <jsynacek@redhat.com>]

Hello,

There seems to be a bug(?) when calling ping with -I lo:

$ ping -I lo kernel.org

PING kernel.org (149.20.4.69) from 192.168.1.10 lo: 56(84) bytes of data.
^C

Note that 192.168.1.10 is my primary interface's address (em1). However, no
replies are coming back.

$ ping -I em1 kernel.org

PING kernel.org (149.20.4.69) from 192.168.1.10 em1: 56(84) bytes of data.
64 bytes from pub2.kernel.org (149.20.4.69): icmp_seq=1 ttl=42 time=202 ms
64 bytes from pub2.kernel.org (149.20.4.69): icmp_seq=2 ttl=42 time=187 ms
^C

Works as expected.

I know that binding to loopback probably doesn't make much sense, but I think
that ping should be able to cope with that.

Also, it would be nice to mention the difference between -I <ip> and -I <iface>
in the manpage.

I don't understand the problem clearly enough to write a patch.

Regards,
-- 
Jan Synacek
Software Engineer, BaseOS team Brno, Red Hat