In Debian bug #507541, Adrian Bridgett reported: "I use multiplexed connections. If in a slave SSH session I type "~C" to open an SSH command prompt, nothing appears to happen. If I look at the master SSH session though I see the "ssh>" prompt has appeared there :-) Not the end of the world, though it did confuse me for a while (not least as it hangs the slave session until I've entered a command on the master session)."
Created attachment 1583 [details] disable ~C for multiplexed slave connections This patch takes the easy way out and just disables ~C for multiplex slave connections. I'd like to fix it properly (i.e. make ~C work for slaves too), but it is quite a bit of work - clientloop.c:process_cmdline() would need a read_passphrase() equivalent that worked with the stdio Buffers.
put this on the list for 5.2
patch applied - this fix will be in openssh-5.2. Thanks for the report.
Close bugs fixed/reviewed for openssh-5.2 release
Perhaps a feature bug needs to be created to track Damien's comment that really this needs reimplementing in the slave - after all when I have four ssh sessions open I have _no_ idea which is the master more often than not!