Does this do what you want?
Code:
[root@perl todd]# ethereal -i eth0 -k -f "net 192.168.10.0/24"
[root@perl todd]#
For tcpdump, it is similar.
Code:
[root@perl todd]# /usr/sbin/tcpdump -i eth0 net 192.168.10.0/24
tcpdump: listening on eth0
20:07:13.893290 perl.631 > 255.255.255.255.631: udp 134 (DF)
20:07:44.923567 perl.631 > 255.255.255.255.631: udp 134 (DF)
2 packets received by filter
0 packets dropped by kernel
[root@perl todd]#