WARNING: failed to install socket filter

[Nicole Hähnel]

Hi,
after starting nagios I get error messages pinging other hosts
(on 2 machines tried, same result):

[root at Notes-FFM2 var]# ping 172.27.48.4
PING 172.27.48.4 (172.27.48.4) from 172.27.16.235 : 56(84) bytes of data.
64 bytes from 172.27.48.4: icmp_seq=1 ttl=126 time=51.9 ms
64 bytes from 172.27.48.4: icmp_seq=2 ttl=126 time=29.2 ms
64 bytes from 172.27.48.4: icmp_seq=3 ttl=126 time=43.2 ms
64 bytes from 172.27.48.4: icmp_seq=4 ttl=126 time=18.4 ms
64 bytes from 172.27.48.4: icmp_seq=5 ttl=126 time=28.5 ms
64 bytes from 172.27.48.4: icmp_seq=6 ttl=126 time=23.8 ms
64 bytes from 172.27.48.4: icmp_seq=7 ttl=126 time=27.6 ms
64 bytes from 172.27.48.4: icmp_seq=8 ttl=126 time=15.4 ms
64 bytes from 172.27.48.4: icmp_seq=9 ttl=126 time=57.1 ms
64 bytes from 172.27.48.4: icmp_seq=10 ttl=126 time=29.8 ms
64 bytes from 172.27.48.4: icmp_seq=11 ttl=126 time=21.9 ms
64 bytes from 172.27.48.4: icmp_seq=12 ttl=126 time=19.2 ms
64 bytes from 172.27.48.4: icmp_seq=13 ttl=126 time=21.4 ms
WARNING: failed to install socket filter
: Protocol not available

This also occurs in the host details,
I see ping OK, but then 
WARNING: failed to install socket filter
: Protocol not available

It's Redhat Linux with kernel 2.4.18 and 2.4.19.
There are 42 hosts to be checked.

What's wrong with this?

Thanks in advance
Nicole



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