Linux HOWTO Enable Miltucast Ping (ICMP) Replies (Echo)

Posted on April 21, 2011 by admin

The 2.6 Linux kernel does not respond to multicast ICMP Echo requests by default. This is a setting in /proc/sys/net/ipv4/icmp_echo_ignore_broadcasts

Test it:

# cat /proc/sys/net/ipv4/icmp_echo_ignore_broadcasts
1
#

Set it to 0 for ping replies:

# echo "0" > /proc/sys/net/ipv4/icmp_echo_ignore_broadcasts
# cat /proc/sys/net/ipv4/icmp_echo_ignore_broadcasts
0
#

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