How does scp traffic flow between two remote hosts?

If you issue a scp command between 2 remote servers, will the traffic flow directly between the hosts, or will it flow from R开发者_运维问答emote1 => Local Machine => Remote2?

For example I issue this command on my laptop:

scp user1@remote1.com:/Files user2@remote2.com:/Files

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Newer versions of scp (since 2011) have the option -3 which will route the traffic through your local machine. This is useful if the hosts are on different networks and can't see each other. Found this on SuperUser. From your linked article it seems like normally the hosts will try to connect directly to each other.

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Looks like it can be done.

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If your linux/bsd/unix or Mac do not have the -3 option, just compile the last version from: http://www.openssh.org/portable.html

It is as simple as:

./configure; make ; sudo make install

It will be installed on /usr/local/bin by default. I just did that on my Mac OS X Lion.