Sometimes it's handy to change the time interval that Linux has to check tcp connection statusses.

Current setting in seconds:
# cat /proc/sys/net/ipv4/tcp_keepalive_time

Change to 15 minutes:
# echo 900 > /proc/sys/net/ipv4/tcp_keepalive_time

This is not permanent ..  and you must place in an init proc...
# vi /etc/sysctl.conf
net.ipv4.tcp_keepalive_time =900

The following settings I used for Cloverleaf software for memory management:

# vi /etc/sysctl.conf
kernel.shmmax=2147483648
#kernel.sem=250 32000 100 256
kernel.sem=300 40000 150 384
fs.file-max=65536