Linux – Postfix Connection refused (port 25)

My guess is it's a firewall issue. To diagnose, either switch to root or use sudo to execute these commands described below:

Firstly, service iptables status will show you your current rules. Depending on how esoteric your firewall rules are, you may need to add them into the main question to debug but essentially you're looking for a line that accepts TCP port 8800 prior to a line that rejects all connections.

e.g.

Table: filter
Chain INPUT (policy ACCEPT)
num  target     prot opt source       destination
...
14   ACCEPT     tcp  --  0.0.0.0/0    0.0.0.0/0      state NEW tcp dpt:8800
15   REJECT     all  --  0.0.0.0/0    0.0.0.0/0      reject-with icmp-host-prohibited

If you don't have a REJECT line on your input chain, then the firewall is probably already turned off.

One way to get around this is obviously to turn off the firewall (service iptables stop) although this defeats the entire purpose of having a firewall.

If you need to add a new firewall rule, you have a couple of options:

1. Use the excellent Firewall Configuration tool (system-config-firewall) that ships with Fedora and can be found at the System->Administration->Firewall menu item in Gnome.

2. On the command line, insert a new rule before the REJECT rule by executing the following (uses numbers from my example above): iptables -I INPUT 15 -m state --state NEW -m tcp -p tcp --dport 8800 -j ACCEPT. NOTE that these changes are not permanent and will not persist beyond the next reboot.

3. Manually edit the /etc/sysconfig/iptables file and add a rule (-A INPUT -m state --state NEW -m tcp -p tcp --dport 8800 -j ACCEPT) to the firewall prior to the REJECT rule. Cycle the firewall service to pick up the changes via a service iptables restart. These changes will be applied every time the firewall service is started.

This error is telling you that MySQL isn't listening on the port specified.

Can you connect to MySQL using the command line client (e.g. mysql -H127.0.0.1 -P3306?)

I doubt you can if both postmap and telnet are telling you they can't connect. Check the port that you're using - has this been changed from the default? Look in /etc/my.cnf as a first port of call for the current MySQL server config.

Check MySQL is running. Depending on your distribution and how you installed MySQL there are various ways to do this, but check the output of:

ps -ef | grep mysql

You should find at least one mysqld process running.

If it's not running, start the server. If you've got a relatively "normal" install, this can be done using init.d scripts as root (normally something like /etc/init.d/mysql start).