this depends on your Linux distribution
in SuSE open YAST
in RHEL this AFAIK is kudzu
go to the networking settings and insert it there
another possibility:
cd to /etc/sysconfig/network and open the file "routes" with an editor
and change the IP after the word "default" to 192.168.15.2
Message was edited by:
oreeh
A gateway never has a netmask assigned since it's always on the local network