I frequently need to copy files between hosts that cannot connect to each other (different private network, firewall, etc.). There's a third host (my working machine usually) that can connect to both of them (let's call it proxy host), so I use scp on that host to do the copying. Currently, I have to copy the files from the source host to the proxy host and then from the proxy host to the target host using two different scp invocations because scp tries to be smart and connect directly from the source host to the target host. It would be great if scp had a "proxy mode" where it connects both to the source host and the target host, just passing through the files.
I don't think any of the developers have a desire to add this sort of feature to scp (it is essentially unmaintainable), but if you would prefer to add it to sftp then please raise another bug.
Change all RESOLVED bug to CLOSED with the exception of the ones fixed post-4.4.
FWIW this has since been implemented and included in OpenSSH 5.7. From http://openssh.org/txt/release-5.7: * scp(1): Add a new -3 option to scp: Copies between two remote hosts are transferred through the local host. Without this option the data is copied directly between the two remote hosts.
implemented for bug #1837 by adding of the -3 option to scp(1)