Rsync is a great cross-platform utility that allows you to sync files and folders. This utility is used for data backup and is considered one of the best among users of different operating systems.
Amanda is also a cross-platform application that will allow you to back up your data. Its big advantage is the support of its own utilities and formats for backup, and you can also configure one server for backup from multiple computers on the network.
CheckMK is an important application for b2b email list tracking a site or server. This utility allows you to track the performance of the site and your server, and will also notify you of problems and new events that have occurred.
Stacer - an application that allows you to monitor the status of the server.
Thanks to this application, you can see what the load is on the server, which applications are running, and you can also interrupt applications and much more.
A very useful utility.
Antivirus
ClamAV - Good protection for your server. This antivirus is one of the most popular and it can protect you from a Trojan, scans mail gateways and much more. Interactions with it occur via the command line, which is also a bonus for some users.
Sophos - Antivirus that can be used for free, as well as for a fee. It is cross-platform and the percentage of virus detection is very high, it is also considered one of the good antiviruses for your server. You can also interact with it through the console or through the interface.