[gentoo-user] Machine doesn't respond to broadcast ping.

[Stroller <stroller@stellar.eclipse.co.uk>]

Hi there,

I've got one machine here on the LAN which isn't responding to  
broadcast ping. Any idea why not?

$ ping -c 2 192.168.1.255
PING 192.168.1.255 (192.168.1.255): 56 data bytes
64 bytes from 192.168.1.71: icmp_seq=0 ttl=64 time=0.221 ms
64 bytes from 192.168.1.43: icmp_seq=0 ttl=64 time=0.301 ms (DUP!)
64 bytes from 192.168.1.22: icmp_seq=0 ttl=64 time=0.405 ms (DUP!)
64 bytes from 192.168.1.255: icmp_seq=0 ttl=255 time=0.649 ms (DUP!)
64 bytes from 192.168.1.9: icmp_seq=0 ttl=60 time=1.646 ms (DUP!)
64 bytes from 192.168.1.71: icmp_seq=1 ttl=64 time=0.159 ms

--- 192.168.1.255 ping statistics ---
2 packets transmitted, 2 packets received, +4 duplicates, 0% packet loss
round-trip min/avg/max/stddev = 0.159/0.564/1.646/0.509 ms
$ ping -c 3 192.168.1.100
PING 192.168.1.100 (192.168.1.100): 56 data bytes
64 bytes from 192.168.1.100: icmp_seq=0 ttl=64 time=0.297 ms
64 bytes from 192.168.1.100: icmp_seq=1 ttl=64 time=0.270 ms
64 bytes from 192.168.1.100: icmp_seq=2 ttl=64 time=0.272 ms

--- 192.168.1.100 ping statistics ---
3 packets transmitted, 3 packets received, 0% packet loss
round-trip min/avg/max/stddev = 0.270/0.280/0.297/0.012 ms
$


It's a fairly recent (last 6 months or so) Gentoo build, and is  
updated fairly regularly (every month or so).

I'd list package versions & stuff, but I have no idea which apply - I  
thought that ping was a part of the basic TCP/IP stack. Would it help  
if I posted the kernel .config? Is there an option in there to disable  
broadcast ping responses?

This isn't very important, but it does pique my curiosity. There are  
many on here more knowledgeable than I, so perhaps someone will  
quickly identify the cause?

Stroller.