A Incorrect MAC received on packet occur during PuTTY session.

[Aimeast]

It is found a problem when test the #9. PuTTY may throw Incorrect MAC received on packet during shell session.

[Aimeast]

Reproduce

1. Connect via PuTTY by default
2. Just run command dir in shell and repeat about 5~15 times
3. PuTTY may throw the Incorrect MAC ERROR

I dont know why PuTTY may received Incorrect MAC, but ssh.exe looks like OK. Maybe chose a difference encryption algorithm.

[Aimeast]

Because PuTTY needs to send package winadj@putty.projects.tartarus.org, HERE https://tartarus.org/~simon/putty-snapshots/htmldoc/AppendixF.html. Some of synchronization mechanism goes wrong. (send a packet with repeating outbound packet sequence)

[acid2000]

But a ChannelFailureMessage is sent as the spec says.

I’ve seen this issue with the standard Ubuntu ssh client.

I think it might be related to multiple channels sending data at the same time and the crypto going out of sync

[Aimeast]

Hi @acid2000 , I pushed this commit 92bb558#diff-92634550b79326c13fac2679d286573fR374 .

Could you please test it is fixed or not?

[Aimeast]

Anyone else found this question still exists?

[robeving]

I patched session.cs on my build. Seems to fix the bug / I wasn't able to reproduce the original issue.