path: root/doc/forwarding.dox
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author√Čric Bischoff <eric@bureau-cornavin.com>2010-08-27 16:20:17 +0200
committerAndreas Schneider <asn@cynapses.org>2010-08-27 16:20:17 +0200
commit31ad140d20c37669ed0ed931e0eed0e4c7aa3f44 (patch)
treecd1d9754d742c6a78d4472cb8fc8a4fdb6b4abce /doc/forwarding.dox
parentbcf4e56fe02042af1accd01b207870a55e1c65b4 (diff)
doc: More work on the tutorial.
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+@page forwarding Chapter 7: Forwarding connections
+@section forwarding_connections Forwarding connections
+Port forwarding comes in SSH protocol in two different flavours:
+direct or reverse port forwarding. Direct port forwarding is also
+named local port forwardind, and reverse port forwarding is also called
+remote port forwarding.
+@subsection forwarding_direct Direct port forwarding
+Direct port forwarding is from client to server. The client opens a tunnel,
+and forwards whatever data to the server. Then, the server connects to an
+end point. The end point can reside on another machine or on the SSH
+server itself.
+Example of use of direct port forwarding:
+Mail client application Google Mail
+ | ^
+ 5555 (arbitrary) |
+ | 143 (IMAP2)
+ V |
+ SSH client =====> SSH server
+--P-->: port connexion through port P
+=====>: SSH tunnel
+A mail client connects to port 5555 of a client. An encrypted tunnel is
+established to the server. The server connects to port 143 of Google Mail (the
+end point). Now the local mail client can retreive mail.
+@subsection forwarding_reverse Reverse port forwarding
+The reverse forwarding is slightly different. It goes from server to client,
+even though the client has the initiative of establishing the tunnel.
+Once the tunnel is established, the server will listen on a port. Whenever
+a connection to this port is made, the server forwards the data to the client.
+Example of use of reverse port forwarding:
+ Local mail server Mail client application
+ ^ |
+ | 5555 (arbitrary)
+ 143 (IMAP2) |
+ | V
+ SSH client <===== SSH server
+--P-->: port connexion through port P
+=====>: SSH tunnel
+In this example, the SSH client establishes the tunnel,
+but it is used to forward the connections established at
+the server to the client.
+*** To be written ***