The Internet was designed and developed on UNIX systems. Internet clients and servers (Web, FTP, mail, news) first implemented on the BSD version of Linux. DARPANET, the precursor of the Internet, was set up to link the UNIX system at different universities across the nation.
- Apache Web Server apache.org: The Apache HTTP Server is a free and open-source cross-platform web server software released under the terms of Apache License 2.0. It is developed and maintained by an open community of developers under the auspices of the Apache Software Foundation.
- Very Secure FTP Server vsftpd: A GPL licensed FTP server is the most secure, stable and fastest FTP server for UNIX-like systems including Linux
- ProFTPD FTP Server proftd.org: It's free and open-source software, compatible with Unix-like systems and Microsoft Windows (via Cygwin).
- Internet Server Consortium (BIND, INN, DHCPD) isc.org: Founded in 1994, ISC is a nonprofit 501(c)(3) public benefit corporation dedicated to supporting the Internet community with software essential to its infrastructure. The organization is the custodian and distributor of commercial quality Open-Source software for the Internet Community. They are specialized in DNS, DNSSEC, BIND, DHCP, Consulting, Software Development, DNS Root Operations, Open Source, Kea, and IPv6 Operations and Deployment. ISC operates F-Root (one of the 13 root DNS servers) as a public service to the Internet.
- Sendmail Mail Server sendmail.org: It is a general-purpose internetwork email routing facility. It supports mail-transfer and delivery methods, including the Simple Mail Transfer Protocol (SMTP) used for email transport over the Internet.
- Postfix Mail Server postfix.org: Postfix is a free and open-source mail transfer agent (MTA) that routes and delivers electronic mail. Licensed by IBM Public License or Eclipse Public License
- Squid Proxy Server squid-cache.org: Squid is a caching and forwarding HTTP web proxy. It speeds up a web server by caching repeated requests, caching web, DNS and other computer network lookups for a group of people sharing network resources, and aiding security by filtering traffic.
- Samba SMB Server samba.org: Samba is free software licensed by GPLv3 for re-implementation of the SMB networking protocol developed by Andrew Tridgell. Samba provides file and print services for various Microsoft Windows clients and can integrate with a Microsoft Windows Server domain, either as a Domain Controller or as a domain member.
Using Samba servers, Linux and Windows systems can share directories and printers.
Edit /etc/samba/samba.conf to specify the name of the windows network. Users can use the SWAT configuration tool to configure samba servers.
- IP Tables Firewall netfilter.org: A command-line firewall utility that uses policy chains to allow or block traffic. When a connection tries to establish itself on a system, iptables look for a rule in its list to match it to. If it doesn't find one, it resorts to the default action.
- Kerberos Network Authentication Protocol web.mit.edu/kerberos/www: A computer-network authentication protocol based on tickets to allow nodes communicating over a non-secure network to prove their identity to one another in a secure manner.
- Open Secure Shell openssh.com: It facilitates encryption for network sessions using a protocol called Secure Shell (SSH).