[...]
Tunnelling solutions commonly used outside the Tcl world include SSH port forwarding, Zebedee, Stunnel [L1 ], ...
See SSL Tunnel for a script that tunnels through web proxy servers using tls.
SockSpy can also be used for tunnelling. For example, I've used it to access my university's news feed machine from a remote site (the news feed machine would only accept local connections). KPV
See also
Another recipe, for use in establishing a tunnel into a firewalled LAN that, in principle, only allows outbound SSH:
ssh -f -l special_user -N -g -R 6005:localhost:22 external_server
Then, from the external_server prompt:
ssh -p 6005 my_account@localhost
This logs into my_account@firewalled_host.
This should only be used under supervision and with explicit permission from the guardians of firewalled_host, of course.
MJ - If you are behind a proxy that will only allow traffic on port 80 and you have a box you have shell access on, you can use the following script to forward requests to port 80 to another endpoint.
set dstport 8888
set dsthost host.i.want.to.go
proc transfer {src dest} {
set data [read $src]
if {[eof $src] || [eof $dest]} {
close $src
close $dest
}
catch {
puts -nonewline $dest $data
flush $dest
}
}
proc conn {socket args} {
set s [socket $::dsthost $::dstport]
puts "connection $socket $args -> $s"
fconfigure $s -blocking 0 -translation binary -encoding binary
fconfigure $socket -blocking 0 -translation binary -encoding binary
fileevent $s readable [list transfer $s $socket]
fileevent $socket readable [list transfer $socket $s]
}
socket -server conn 80
vwait forever