tcp_scan and udp_scan are tools to scan a host for available network
services (for example, to see if your packet filter does its job). You
can scan specific services or ranges of ports.  In order to speed up
the process, the tools probe a bunch of network ports in parallel.

The programs work with SunOS 4.1.3, SunOS 5.3 (Solaris 2.3) and
probably with anything that looks like 4.3+ BSD or System V.4.

There is one catch, though: the programs use raw ICMP sockets, so they
need to be run with root privilege. Raw ICMP sockets are used to work
around common shortcomings in BSD (75-second timeout on a non-blocking
TCP connect() to an unreachable host) and in SYSV (a connected UDP
socket does not pass delivery errors back to the application).

Warning: these programs will raise lots of alarms on sites that run my
tcp wrapper or that do any other kind of network monitoring.  Use the
programs only with prior permission from the affected sites.

	Wietse Venema
