OpenVPN is a robust and highly configurable VPN (Virtual Private Network) daemon which can be used to securely link two or more private networks using an encrypted tunnel over the Internet. OpenVPN's principal strengths include wide cross-platform portability, excellent stability, support for dynamic IP addresses and NAT, adaptive link compression, single TCP/UDP port usage, a modular design that offloads most crypto tasks to the OpenSSL library, and relatively easy installation that in most cases doesn't require a special kernel module.
The MiniUPnP project is a library and a daemon. The library is aimed to enable applications to use the capabilities of a UPnP Internet Gateway Device present on the network to forward ports. The daemon adds the UPnP Internet Gateway Device functionality to a NAT gateway running OpenBSD/NetBSD/FreeBSD/Solaris with PF/IPF or Linux 2.4.x/2.6.x with netfilter. One of its most interesting features is to enforce some permissions to allow or deny redirections, bringing some security to UPnP. Newer versions also support the NAT-PMP protocol from Apple.
UCARP allows a pair of hosts to share common virtual IP addresses in order to provide automatic failover. It is a portable userland implementation of the secure and patent- free Common Address Redundancy Protocol (CARP, OpenBSD's alternative to VRRP). Strong points of the CARP protocol include its very low overhead, cryptographically signed messages, interoperability between different operating systems and no need for any dedicated extra network link between redundant hosts.
vpnd is a daemon which connects two networks on network level either via TCP/IP or a (virtual) leased line attached to a serial interface. All data transfered between the two networks are encrypted using the unpatented free Blowfish encryption algorithm with a key length of up to 576 bits (may be downgraded to a minimum of 0 bits to suit any legal restrictions).
NetUP UTM is a universal billing system for internet service providers of any size. Its modern approach to traffic accounting makes the system compatible with all popular platforms and network devices. Its key features include realtime traffic processing, Cisco Netflow and IP Accounting data collection, support for RADIUS authentication, and cross-platform compatibility. The core of the system is a smart and reliable accounting engine working directly with network equipment. It supports up to 100,000 users at a total speed of up to 3 Gbps. A flexible ratings engine and efficient administration tools make UTM a complete solution for IP/VoIP/WiFi/dial-up billing.
NatACL is a Linux firewall group policy controller for intranets and Internet. Using a internal DHCP server, it can force users to use a DHCP client, and you can block static IPs. It will bind an IP to a MAC address and enforce this usage. You can control groups that can see each other with intranet policies, or control who has access to the Internet. It also has an option to force users to authenticate themselves over the Web before accessing the Internet.
SING stands for 'Send ICMP Nasty Garbage.' It is a tool that sends ICMP packets fully customized from command line. Its main purpose is to replace and complement the ping command, adding certain enhancements as fragmentation; send and receive spoofed packets; send many ICMP information types (echo as the old ping, address mask, timestamp, and router discovery) and errors (redirect, unreach, and time exceeded); and send monster packets. It also supports loose and strict source routing and record routing.
mxallowd is a daemon for Linux Netfilter (using libnetfilter-queue) and BSD pf (using pflog) which implements a slightly improved nolisting mechanism. It requires your name server to be configured to return two MX IP addresses, and the one with higher priority must not run a mail server on port 25. mxallowd blocks attempts to connect to the mail server unless the sender tries to connect to the first mail server before the second. Since most spammers will attempt direct connections to each mail server, they will be blocked.