This article is from the Firewalls FAQ, by Matt Curtin cmcurtin@interhack.net and Marcus J. Ranum mjr@nfr.com with numerous contributions by others.
Telnet is generally supported either by using an application proxy such as
the firewall toolkit's tn-gw, or by simply configuring a router to permit
outgoing connections using something like the ``established'' screening
rules. Application proxies could be in the form of a standalone proxy
running on the bastion host, or in the form of a SOCKS server and a modified
client.
 
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