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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

3 Answers 3

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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.

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  • Is HPN SSH required on boths sides of the connection, or is the originating end good enough?
    – vfclists
    Commented Apr 29, 2017 at 5:21
  • Encryption options and the TCP windows are negotiated. So both ends have to participate.
    – BowlOfRed
    Commented Apr 29, 2017 at 7:52
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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.

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    But be very careful with the glaring security problems of the R protocols.
    – vonbrand
    Commented Oct 5, 2015 at 1:37
  • 1
    Should rsh be safe if I restrict it to particular networks or hosts, ie in an internal network or a vpn?
    – vfclists
    Commented Oct 5, 2015 at 12:43
  • How do you use rsh instead of ssh? Commented Dec 9, 2020 at 19:51
  • @SteveRobbins added a note on how to use it
    – seumasmac
    Commented Dec 10, 2020 at 8:39
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This server fault answer claims that one of the primary benefits of using the rsync daemon mode is the lower CPU overhead.

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