Free what is a server software for linux

Darwin Calendar Server provides a CalDAV server.

The Darwin Calendar Server is a standards-compliant server that allows multiple users to collaboratively share calendaring information. It provides a shared location on the network to store schedules, and allows users to send each other and manage invitations.

In order to provide interoperability with multiple calendaring clients, the server implements the CalDAV protocol, which is an extension of WebDAV, which is in turn an extension of HTTP.

RIPE Whois Server provides support for domain records and lookups.

This is a whois database server. The RIPE Whois server uses a backend SQL database to allow support for very large repositories. There is support for IPv6 records and lookups. Both RPSL and RIPE181 are supported.

Linx Kiss Server project was primarily intended for personal purpose. I couldnt make any of available kiss linux servers work with my new Kiss DP-600 player in a way I would imagine so I found kissd simple kiss daemon by Alexandre Becoulet which is really simple and clear code to understand and fixed it up and added some more features.
Linux Kiss Server (LKS) works with Kiss DP-600 but I think it should work with any other Kiss player as well.
Main features:
- makes selected direcotory accessible for Kiss player
- can run either as a daemon or in foreground
- can answer Kiss player queries for PC-LINK server
- can disable UDP binding at all (doesnt respond to Kiss player looking for PC-LINK server queries)
- can overide default server port
Enhancements:
- A problem with zombie processes when the opening of files failed was fixed.
- TIME_WAIT sockets are now closed correctly.
- Events are now logged using syslog when the server is run in daemon mode.

Campus Chat Server project is a chat server intended for use in the Cadiz University campus network.
Enhancements:
- hash_maps are now used instead of maps, so the cost of lookup or insertion is O(1) in the average case, instead of O(logn).

Tigase Server project is a lightweight and scalable Jabber/XMPP server. No third party libraries are needed. For services with very high load and a huge number of users, it can be deployed on as many machines as needed.
Enhancements:
- This release corrects and improves the packet filter, adds a startup script for Mandriva Linux, and fixes a problem with stream initialization on very fast machines.
- The IOService class is now synchronized.
- There are many performance improvements, and processing packets from/to remote servers has been added.

Dual DHCP DNS Server is a combined DHCP/DNS server for small LANs.
Dynamic DHCP allocates/renews host addresses, while the caching DNS server first tries resolving from DHCP-allotted names, then from cache, and only then forwarding to external DNS servers.
Dual DHCP DNS Server supports an optional static DHCP mode and static IPs, automatic dynamic DNS updates from DHCP, and the ability to co-exist with other DHCP servers.
It is self-configuring and doesnt require the creation of zone files, and uses little memory and CPU.
Enhancements:
- This release fixes zone replication bugs.