Corrupted MAC problem on PSOS platform

Darren Tucker dtucker at
Sun Sep 10 14:42:54 EST 2006

Jim Fan wrote:
> Hi Group,
> I am porting openSSH to an embedded platform running pSOS. I am able
> to setup a connection with the server but after I disconnect and
> reconnect, I always get the following error message and client won't
> establish connection with the server.
> Disconnecting: Corrupted MAC on input.
> Disconnecting: Corrupted MAC on input.

What's on the network between client and server?  Some network devices 
(eg certain firmware revs of Linksys routers) have been reported to 
cause this.

The possible causes we know about are documented here:

Failing that, I would try compiling everything (zlib, openssl and 
openssh) without any optimization and seeing if that makes a difference.

> I checked key exchanges in both connections and they all looked ok.
> Any ideas why MAC check would fail on second connection attempt?

Maybe the different DH parameters negotiated in the DH GEX has some 
effect?  Try removing the moduli file on the server and it will fall 
back to group1 or group14.

Darren Tucker (dtucker at
GPG key 8FF4FA69 / D9A3 86E9 7EEE AF4B B2D4  37C9 C982 80C7 8FF4 FA69
     Good judgement comes with experience. Unfortunately, the experience
usually comes from bad judgement.
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