Sys Admin Guides, How To's, etc by Marios Maravelias

when you try to backup the databases of the websites from Plesk Backup util and you get failure and the message “Failed to connect to database: User ‘admin’ has exceeded the ‘max_user_connections’ resource (current value: 10)” you have to change the mysql options

(more…)

This happened to a Plesk 8.x Linux (RH) server, the problem was that smtp service was up and running, and the queue was very light , but smtp wouldn’t accept any connections at port 25 even from localhost.

In the /var/log/messages I saw this disturbing message:
xinetd[#]: Deactivating service smtp due to excessive incoming connections. Restarting in 30 seconds.

(more…)

You can check what connection you have via smtp protocol with the simple command:

netstat -a | grep smtp

(more…)

This is a very simple script to run and check how many connections each service (Apache,MySQL,SMTP (qmail)) has.

You only have to fill this: {mysq_ladmin_pass} with your mysql administrator password.

#!/bin/sh

pass={mysq_ladmin_pass}

echo “Apache Connections (port 80):” `netstat -an |grep :80 |wc -l`
echo “MySQL Connections (port 3306):” `mysqladmin -uadmin -p”$pass” processlist |wc -l`
echo “SMTP Connections (port 25):” `netstat -an |grep :25 |wc -l`

APF Deny ALL for SSH – Limit IP Connections

APF firewall can deny ALL connections for ssh and allow only a single or select few of IPs to connect to your server. We’ll guide you through DENY ALL with APF firewall.

(more…)