The NET-SNMP (formerly UCD-SNMP) package contains various tools relating to the Simple Network Management Protocol including an extensible agent, an SNMP library, tools to request or set information from SNMP agents, tools to generate and handle SNMP traps, a version of the unix 'netstat' command using SNMP and a Tk/perl mib browser. It was originally based on the Carnegie Mellon University SNMP implementation (version 126.96.36.199), but has been greatly enhanced, ported and fixed and barely resembles the original package anymore.
Angst is an active sniffer, based on libpcap and libnet. It dumps into a file the payload of all the TCP packets received on the specified ports. It implements two methods for active sniffing. Angst is able to monitor ARP requests, and after enabling IP forwarding on the local host, it sends ARP replies mapping all IPs to the local MAC address. Also, it can flood the local network with random MAC addresses (like macof), causing switches to send packets to all ports.
Ganglia is a scalable distributed monitoring system for high-performance computing systems such as clusters and grids. It is based on a hierarchical design targeted at federations of clusters. Ganglia is currently in use on over 500 clusters around the world and has scaled to handle clusters with 2000 nodes.
Dante is a free implementation of the proxy protocols SOCKS version 4 and SOCKS version 5 (RFC 1928). It can be used as a firewall between networks, controlling outgoing traffic. The package consists of two parts: a socks server and a proxy client that supports socks, HTTP proxies, and UPnP. RFC 1961 (GSSAPI) is supported in both the client and the server. Commercial support is available.
Addns.pl is a self-contained DynDNS update client for DynDNS.org (and possibly others). It supports a variety of IP detection methods including external webcheck/router pages. It also supports multiple configurations and hostnames, smart abuse prevention, and custom/static/dynamic DNS, and can run as a daemon, commandline options only, or with a configuration file.
The Internet Software Consortium DHCP distribution includes a DHCP client, a DHCP server, and a DHCP relay agent. DHCP is a protocol for automatically configuring nodes on an IP network. The ISC DHCP server and client are well known for being extremely configurable, reasonably easy to use, and quite efficient.