This problem has reared its head in perl 5.14.2 on FreeBSD 8.3 in the execution of postgrey. Turning off taint checking makes the error go away.
postgrey --inet=10023 --pidfile=/var/run/postgrey.pid \
--user=postgrey --group=postgrey --dbdir=/var/db/postgrey
2013/03/27-08:53:46 postgrey (type Net::Server::Multiplex) starting! pid(45305)
Resolved localhost:10023 to ::1:10023, IPv6
Resolved localhost:10023 to ::1:10023, IPv6
Resolved localhost:10023 to 127.0.0.1:10023, IPv4
Resolved localhost:10023 to 127.0.0.1:10023, IPv4
Duplicate configuration (TCP) on ::1:10023 with IPv6) - skipping
Duplicate configuration (TCP) on 127.0.0.1:10023 with IPv4) - skipping
Binding to TCP port 10023 on host ::1 with IPv6
Insecure dependency in socket while running with -T switch at /usr/local/lib/perl5/site_perl/5.14.2/mach/IO/Socket.pm line 80.
Is the bug in perl itself or in the perl modules it calls? All have been rebuilt and reinstalled from source in the past few days to ensure nothing was damaged or out of date.
FWIW, it doesn't happen if you choose the unix domain socket but then you can't daemonize the process on the command line: you can add an & but you can't use the -d argument.
Details:
===> postgrey-1.34_4 depends on package: p5-Net-Server>=0 - found
===> postgrey-1.34_4 depends on package: p5-IO-Multiplex>=0 - found
===> postgrey-1.34_4 depends on package: p5-Parse-Syslog>=0 - found
===> postgrey-1.34_4 depends on package: p5-BerkeleyDB>=0 - found
===> postgrey-1.34_4 depends on package: p5-Net-DNS>=0 - found
===> postgrey-1.34_4 depends on file: /usr/local/bin/perl5.14.2 - found
make pretty-print-run-depends-list
This port requires package(s) "db47-4.7.25.4 p5-BerkeleyDB-0.51 p5-Digest-HMAC-1.03 p5-IO-Multiplex-1.13 p5-IO-Socket-INET6-2.69 p5-Net-DNS-0.72 p5-Net-Server-2.007 p5-Parse-Syslog-1.10 p5-Socket6-0.23 perl-5.14.2_3" to run.