How can I keep rsync from using encryption and compression for the file transfers after the connection is authorized?

Question

I understand that a secure connection (i.e. ssh) is needed to authorize a connection to the remote server. But after that is authorized can the data be transmitted without encryption and compression as well?

I am transferring files in the local network and could do without the overhead of compression and encryption, or even the attempt to compress then if they are suitable. Compression may be fine if it speeds things up, but encryption is not. I know of alternatives like FTP, NFS and Samba are available, but I prefer rsync, as the channel is closed once the transfer is complete

Solution 1

Rsync isn't the fastest thing in the world, but for long links I prefer to use it over HPN SSH. This is normal OpenSSH, but with some patches that offer a few benefits. Relevant to what you want, it allows the "none" encryption option for the transfer.

I find it especially valuable at a company where we have WAN accelerators. I can't change their behavior, but because they try to do their own compression/duplicate removal, it works much better if I can feed them an unencrypted data stream.

Solution 2

For your local network, you could use rsync over rsh instead of ssh.

In fact, man rsync gives this as a specific alternative transport to ssh.

As vonbrand points out below, you should be very aware of the security implications of this - it's purely for a local, trusted network.

To use it, you need to set up rsh first, and then you can use rsync --rsh=rsh ... to use this transport rather than the default ssh.

Solution 3

This server fault answer claims that one of the primary benefits of using the rsync daemon mode is the lower CPU overhead.

Comments

[vfclists]

Should rsh be safe if I restrict it to particular networks or hosts, ie in an internal network or a vpn?

[vfclists]

Is HPN SSH required on boths sides of the connection, or is the originating end good enough?

[BowlOfRed]

Encryption options and the TCP windows are negotiated. So both ends have to participate.

[Steve Robbins]

How do you use rsh instead of ssh?

[seumasmac]

@SteveRobbins added a note on how to use it