ERL-469: ssh authentication succeeds w/o ssh-agent, but fails with it

[OTP-Maintainer]

Original reporter: fhunleth
Affected versions: OTP-20.1, OTP-20.2, OTP-20.0
Fixed in version: OTP-20.2.1
Component: ssh
Migrated from: https://bugs.erlang.org/browse/ERL-469

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I'm using an OpenSSH ssh client to connect to an Erlang node running the `ssh` application. The version of OpenSSH is "OpenSSH_7.2p2 Ubuntu-4ubuntu2.2, OpenSSL 1.0.2g  1 Mar 2016". The version of the ssh application is 4.5. 

My ssh private key is password encrypted. If I use `ssh-add` to add the key to the agent and try to connect to the Erlang node, it will fail. If I make it so that the agent doesn't get used, connecting with ssh succeeds after OpenSSH asks me for the password. 

I ran ssh with the -v option and attached the logs below. As far as I can tell these do not provide any insight as to why using the agent breaks authentication.

[OTP-Maintainer]

hans said:

Could you call {{ssh_dbg:messages()}} on the server and than try to connect with and without ssh-agent and post the printouts?

[OTP-Maintainer]

fhunleth said:

Here are the ssh_dbg traces. 

[OTP-Maintainer]

hans said:

Hmmm, I can't see any explanation in the logs.  I will try with a ssh-agent myself and see if I can see something then, but it will take some days.

[OTP-Maintainer]

fhunleth said:

Thanks! I hope that you're able to reproduce it.

[OTP-Maintainer]

ingela said:

Not prioritized at the moment. PR welcome 

[OTP-Maintainer]

hans said:

Solved by OTP-20.2.1

[OTP-Maintainer]

fhunleth said:

Thanks! Looking forward to trying this out!