This is an Erlang rewrite of tcpserver by D.J.Bernstein. Made as a first step of complete Qmail rewrite.
Build tcpserver by make command. You need to have path to erlc in your PATH environment variable. As a result you'll have a single tcpserver executable which accepts the same command line params as original tcpserver does (excpet -u, -g and -U):
Usage: tcpserver [-1XpPhHrRoOdDqQv] [-x <rules.txt>] [-B <banner>] [-c <limit>] [-b <backlog>] [-l <localname>] [-t <timeout>] <host> <port> <program>
Another difference is that rules file is raw text instead of cdb, tcpserver looks for changes in rules file once in a minute and loads new rules if there are any.