If say you want to run apache and tomcat both on port 80 (default), you can create a seperate IP address on an internal network.

For RedHat Distros

$ cd /etc/sysconfig/network-scripts/
$ more ifcfg-eth0:0

DEVICE=”eth0:0″
BOOTPROTO=”none”
ONBOOT=”yes”
IPADDR=”XXX.XXX.XXX.XXX”
NETMASK=”255.255.254.0″
BROADCAST=”XXX.XXX.XXX.255″

$ ifup-aliases eth0

When getting an error stating the PGP key is not correct

rpm –import http://mirror.centos.org/centos-3/RPM-GPG-KEY-CentOS-3

The PGP Key is also reportedly on each CD.

More info at http://www.centos.org/modules/smartfaq/faq.php?faqid=29

For RedHat 9

$ redhat-config-date (except this requires X)

or

$ clock
$ rm /etc/localtime
$ ln -s /usr/share/zoneinfo/Australia/Brisbane /etc/localtime
$ /usr/bin/rdate -s time.nist.gov
$ /sbin/hwclock –systohc

The last two commands can be added to cron for regular syncing with running ntp

0,30 * * * * /usr/bin/rdate -s time.nist.gov >/dev/null 2>&1
1,31 * * * * /sbin/hwclock –systohc >/dev/null 2>&1