Linux – IT Blog

Port forwarding in iptables on NAT server

Once I needed to forward a port to a VPN server that had a gray IP address and was behind NAT.

Zabbix-server process does not terminate

Once I updated Ubuntu server and Zabbix-server by running apt update, apt upgrade, after the update was complete I agreed to restart all updated services, but Zabbix-server continued to be running for 20 minutes and did not restart.

How to configure ODBC for Asterisk

One day I installed new Asterisk 20 from source on Ubuntu Server 22.04 and I needed to record CDR call statistics to a MySQL database since MySQL server was already installed and used by other services. And the cdr_mysql module was removed in Asterisk 19, so I had to configure ODBC to write CDRs to MySQL.

Setting up Fail2ban with IPv6

I will give an example of configuring Fail2ban to work with IPv6 addresses.

Solution rsyslogd: action ‘action-6-builtin:omfile’ resumed (module ‘builtin:omfile’)

One day, on the same server running Ubuntu 20.04, I noticed a lot of messages in /var/log/syslog:

iRedMail. Changing the size of a mail attachment

For example, I’ll take the installed iRedMail-1.6.8 and change the maximum size of the mail attachment.

Solution Unable to retrieve PJSIP transport in Asterisk

The error “Unable to retrieve PJSIP transport …” occurs when TRANSPORT does not exist or is specified incorrectly.

Setting up nftables

In this article I will give examples of setting up nftables to replace the outdated iptables.

How to change gateway in Linux

Once I needed to change the default gateway on different servers without restarting the network service or rebooting the server, I will give examples of how I did this.

Monitoring Linux directory size in Zabbix

One day I needed to monitor the size of a directory in Zabbix and create a trigger so that Zabbix would notify when the directory size increases.