Question

Why ssh from a linux device (w/ Dropbear v2014.66) to RUT240 works but not RUT955? The error I got is "ssh: Connection to [email protected]:22 exited: No matching algo mac c->s". RUT240 and RUT955 both have Dropbear v2019.78 on them. Is there a setting I can change to make it work on the RUT955? It was running RUT9XX_R_00.06.06.1. I upgraded it to the recent factory version RUT9XX_R_00.06.08.6, but still isn't working.

Answer 1

Hello,

On the RUT955, copy /etc/dropbear/dropbear_rsa_host_key to /root/.ssh/id_dropbear mode 0600 and try again.

Regads,

Comments

Upgrading its dropbear would fix the problem. But I'm looking for other alternatives. The question remains as why does it work on RUT240 but not RUT955?

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Because the dropbear on the RUT240 supports at least one algo from (hmac-sha1-96, hmac-sha1, hmac-md5) and the dropbear on the RUT955 doesn't. But they dont say which ones they support ...

Another solution would be to recompile a dropbear for the RUT955 using the SDK.

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Should we be trying legacy build or RUTOS, what's the difference, why is one 400MB and the other only 97MB?

Why are we getting tar: Removing leading '/' from member names?

How do we customize the 955 build to add those packages that you mentioned  (hmac-sha1-96, hmac-sha1, hmac-md5)?

Thank you

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The legacy version contains pre-downloaded packages the RUTOS version doesn't the difference in size is there. Use the RUTOS version, it should contain the required algos by default, else from make menuconfig go to Base system->Dropbear configuration.

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While waiting for it to build I upgraded the RUT955 to RUT9_R_00.07.01.4 because I figure that I would get the same dropbear here. And it worked. Thank you very much for your quick responses and thorough explanations. I appreciate it.