Dialback is a set of html pages and some bash scripts to enable a host to call you back and set up a ppp link. It also includes a MS Windows dial-up networking script should you wish to use such a machine for a client. It is intended for legitimate remote access where you need good security (ppp link only available on return call) and/or the other end is willing to foot the bill for your connection time. Please note that it should be fairly to set up other protocols such as slip.
The Cistron Radius server is mostly compatible with Livingston's 'radiusd-2.1', except without the s/key or menu support. It has additional features such as multiple DEFAULT entries with fall-through, a session database (who is online), the ability to limit connections on a per-user basis, and much more.
PPTP Client allows you to connect to a PPTP server from a Linux box. It sets up a PPTP call, after which the PPP daemon establishes a PPP link over that PPTP call. The client can access PPTP-based VPNs. Besides remote access to internal corporate networks, some CATV and ADSL ISPs are using PPTP to provide Internet access to their customers.
The Linux Virtual Server Project is a project to cluster many real servers together into a highly available, high-performance virtual server. The LVS load balancer handles connections from clients and passes them on the the real servers (so-called Layer 4 switching) and can virtualize almost any TCP or UDP service, like HTTP, HTTPS, NNTP, FTP, DNS, ssh, POP3, IMAP4, SMTP, etc. It is fully transparent to the client accessing the virtual service.
Ganymede is a metadirectory system, primarily intended for UNIX-like environments, but capable of being run with some effort on any server supporting Java 1.1.7 or better. Ganymede supports NIS, DNS, and other network information services, and allows many administrators to work together simultaneously to administer defined subsets of your network directory data. Any system capable of running Java applets with Swing can run the Ganymede client.