When I try to run duplicity between two Ubuntu servers, a message is displayed:

"The authenticity of host ...... can't be established. SSH-RSA key fingerprint is 102:...:...:...:...:......."

The fingerprint appears to be made up of 16 numbers in the 100s-200s range

Does anyone know what this format is please? I'm struggling to find a way to generate it on the target server to compare against.

Edit - if I uninstall duplicity 0.8.20 from the duplicity-release-git PPA and instead install 0.7.17 from the Ubuntu PPA and again try to run the duplicity command it shows the SSH-RSA key fingerprint in the expected Md5 (42:.....) hex format so the issue appears to be related to duplicity 0.8


1 Answer 1


looks like an ssh error, trying to connect a known host with a differing fingerprint. did the target machine switch host keys inbetween now and the last conection via ssh to it?

if you made sure the target machine is correct then you can update or remove the fingerprint in the known host file. just search using your error message you will come up with description on how to do it!

  • Thanks for the reply, I deleted the known_host entries for the server name and IP address to check it wasn't that. The key fingerprint format with duplicity 0.8.20 was really strange - along the lines of 102:159:105:...:...:...:...:...:...:...:. (16 components in total, each a 3-figure number in the 100s). Jul 20, 2021 at 12:00
  • There does seem to be some sort of consistency between the two fingerprints reported ("104" in 0.8.20 maps to "44" in 0.7.17 each time) but I can't work out what the 0.8.20 format is (doesn't appear to be e.g. the decimal equiv of hex values). In any case will go with 0.7.17. Thank you for the suggestions. Jul 20, 2021 at 12:08

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