openbsd-ports/net/httptunnel/pkg/DESCR

httptunnel creates a bidirectional virtual data path tunnelled in HTTP
requests. The requests can be sent via an HTTP proxy if so desired.

This can be useful for users behind restrictive firewalls.  If WWW
access is allowed through an HTTP proxy, it's possible to use
httptunnel and, say, telnet or PPP to connect to a computer outside
the firewall.

WWW: ${HOMEPAGE}