[[...]]




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Tunnelling solutions commonly used outside the Tcl world include
SSH port forwarding,
Zebedee, 
Stunnel [http://www.idg.net/go.cgi?id=739518],
...

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See [SSL Tunnel] for a script that tunnels through web proxy servers using [tls].

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[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]

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See also 
   * [tls]
   * [http]
   * [SSL Tunnel]
   * [Tunnel IRC through HTTP proxies]
   * [Tunnel HTTP through SMTP]






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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.

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[MJ] - If you are behind a proxy that will only allow port 80 and you have a box you have shell access on, you can use the following script to forward requests on 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
 
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[[Comment on OpenVPN.]]
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[[ [Category Internet] ]]