Network Services don't work

You've installed a package, configured it, started it up and it seems to be running fine, but nothing is happening.

Did you forget to add iptables rules for the ports used by your new service? Don't forget that bind9 uses UDP as well as TCP.

Edit /etc/sysconfig/iptables and add rules to open up the necessary ports. You can also use iptables -e commands, but this stops you putting useful comments in your iptables file because iptables gets auto-generated. OTOH, don't hand edit iptables unless you are confident you aren't going to save a broken one and lock yourself out of the system. Never run system-config-securitylevel unless you want to trash your hand-edited iptables file.

Don't forget to 'service iptables restart' after making updates to the file.

Use 'netstat' to debug ports and service issues. For example, netstat -l -t -u -p -e will give a nice display of listening tcp and udp ports. Add --numeric-ports to see port numbers instead of names. The man page for netstat is fairly comprehensible, unlike some.