The DUP System

Yes. However, DUP internally always only sets up stages using UNIX pipes (same dupd parent process) or TCP. In order to get support for another two-party protocol, you should write two small wrapper stages, one client-stage and one server-stage. Those stages should use the uni-directional (!) TCP stream to transmit the server's address to the client (the server stage must hence be run on the sending-end of DUP-created stream). The client stage should then connect to the server. Then both stages should close the original TCP stream created by DUP, use dup2 to take over the original file descriptor and then exec the stage that desires a non-TCP protocol.

With such pairs of stages, you can easily switch to say RTP by wrapping the original process. In DUP, the changes would look like this. Before:

l1@h1[...,1|l2:0] $ data-source;
l2@h2[...] $ data-target;

After:

l1@h1[...,1|l2:0] $ rtp-wrapper-server 1 data-source;
l2@h2[...] $ rtp-wrapper-client 0 data-target;

In this example, the extra arguments "0" and "1" specify the TCP stream to replace by an RTP stream.

The DUP developers plan to provide pairs of such stages for various transport protocols in the near future.