Postfix
What is Postfix? It is Wietse Venema's mail server that started life at IBM research as an alternative to the widely-used Sendmail program. Now at Google, Wietse continues to support Postfix. Postfix runs (or has run) on AIX, BSD, HP-UX, IRIX, LINUX, MacOS X, Solaris, Tru64 UNIX, and other UNIX systems. It requires ANSI C, a POSIX.1 library, and BSD sockets. Postfix attempts to be fast, easy to administer, and secure. The outside has a definite Sendmail-ish flavor, but the inside is completely different. Multiple SMTP deliveries over the same TLS-encrypted connection. This reuses the existing tlsproxy(8) and scache(8) services. MySQL stored procedure support. Gradual degradation: in many cases a Postfix daemon will log a warning and continue providing the services that are still available, instead of immediately terminating with a fatal error. Postfix can set the execute bit on a queue file. If this does not work, then no mail will ever be delivered.
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LXD
LXD is a next generation system container manager. It offers a user experience similar to virtual machines but using Linux containers instead. It's image based with pre-made images available for a wide number of Linux distributions and is built around a very powerful, yet pretty simple, REST API. To get a better idea of what LXD is and what it does, you can try it online! Then if you want to run it locally, take a look at our getting started guide. The LXD project was founded and is currently led by Canonical Ltd with contributions from a range of other companies and individual contributors. The core of LXD is a privileged daemon which exposes a REST API over a local unix socket as well as over the network (if enabled). Clients, such as the command line tool provided with LXD itself then do everything through that REST API. It means that whether you're talking to your local host or a remote server, everything works the same way.
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Zypper
Zypper is a command-line package manager for installing, updating, and removing packages. It can also be used to manage repositories. Zypper works and behaves as a regular command-line tool. It features subcommands, arguments, and options that can be used to perform specific tasks. Zypper offers several benefits compared to graphical package managers. Being a command-line tool, Zypper is faster in use and light on resources. Zypper actions can be scripted. Zypper can be used on systems that do not have graphical desktop environments. This makes it suitable for use with servers and remote machines. The simplest way to execute Zypper is to type its name, followed by a command. Additionally, you can choose from one or more global options by typing them immediately before the command. Some commands require one or more arguments. Executing subcommands in the Zypper shell, and using global Zypper options are not supported.
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ClamAV
ClamAV® is the open-source standard for mail gateway-scanning software. ClamAV includes a multi-threaded scanner daemon, command-line utilities for on-demand file scanning, and automatic signature updates. ClamAV supports multiple file formats and signature languages, as well as file and archive unpacking. Access to ClamAV versions that work with your operating system. ClamAV® is an open-source antivirus engine for detecting trojans, viruses, malware & other malicious threats. ClamAV® is an open-source (GPL) anti-virus engine used in a variety of situations, including email and web scanning, and endpoint security. It provides many utilities for users, including a flexible and scalable multi-threaded daemon, a command-line scanner, and an advanced tool for automatic database updates. Built-in support for various archive formats, including ZIP, RAR, Dmg, Tar, GZIP, BZIP2, OLE2, Cabinet, CHM, BinHex, SIS, and others.
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