To run multiple instances of Apache on port 80 they need to be listening on different IP addresses.
If you have 1 physical network interface eth0, you can set up multiple virtual interfaces like this:
linuxserver# cat /etc/sysconfig/network-scripts/ifcfg-eth0
DEVICE=eth0
BOOTPROTO=static
DHCPCLASS=
HWADDR=01:21:9B:8B:B1:BD
ONBOOT=yes
IPADDR=10.20.1.20
NETMASK=255.255.255.0
GATEWAY=10.20.1.1
linuxserver# cat /etc/sysconfig/network-scripts/ifcfg-eth0:0
DEVICE=eth0:0
BOOTPROTO=static
ONBOOT=yes
IPADDR=10.20.1.21
NETMASK=255.255.255.0
GATEWAY=10.20.1.1
The ifcfg-eth0:0 virtual interface has been added and will listen on 10.20.1.21. eth0 listens on 10.20.1.20.
If you have 2 instances of Apache; 1 in /opt/apache-1 and another in /opt/apache-2 you can do the following:
In /opt/apache-1/conf/httpd.conf you have this line:
Listen 10.20.1.20:80
and in /opt/apache-2/conf/httpd.conf you have this line:
Listen 10.20.1.21:80
After starting both Apache instances you can run a netstat -an and you should see both instances running simultaneously.
