Here is a somewhat fancier version:
Code:

[hijack]
;@MENUEXEC Netmask y=`cat /proc/net/route` && y=${y:162:8} && echo popup 5 "Netmask=$((0x${y:6:2})).$((0x${y:4:2})).$((0x${y:2:2})).$((0x${y:0:2}))" >/proc/empeg_notify