ssh key exchange failure

francisco_1 · ‎03-02-2010

Strange problem trying to scp ios image from a unix server.

router3845#copy scp: flash

Address or name of remote host [192.168.15.3]?
Source username
Source filename [c3845-spservicesk9-mz.124-17.bin]?
Destination filename [c3845-spservicesk9-mz.124-17.bin]?
%Error opening scp://*****@192.168.15.3/c3845-spservicesk9-mz.124-17.bin (Protocol error)

debug ssh/scp output

Mar 1 15:24:34.864 GMT: SSH2 CLIENT 0:
Invalid modulus length
Mar 1 15:24:34.864 GMT: SSH CLIENT0: Session disconnected - error 0x00

Mar 1 15:25:45.098 GMT: SSH CLIENT0: protocol version id is - SSH-2.0-Sun_SSH_1.1
Mar 1 15:25:45.098 GMT: SSH CLIENT0: protocol version exchange successful
Mar 1 15:25:45.198 GMT: SSH2 CLIENT 0:
Invalid modulus length
Mar 1 15:25:45.198 GMT: SSH CLIENT0: key exchange failure (code = 1)
Mar 1 15:25:45.198 GMT: SSH CLIENT0: Session disconnected - error 0x00

I am seeing key exchange failure, I have re-create ssh rsa key with different modulus size on router, unix servers has been checked out, no issues found.

The code on the device is 12.4-20T.

This router is on dmz behind a firewall. FW rules has been checked out and working since we can scp from another router. The only difference between this router and the other one is that this router has 3 rsa keys. I have instructed the router to use a new rsa key using keypair command but issue still exist.

Any ideas?

najumiqbal · ‎03-06-2010

Hi,

Could you please confirm what version of SSH you are using on both side ?

francisco_1 · ‎03-08-2010

ver 2 both sides

hleybovich · ‎05-20-2013

Long shot here, but if you ever got this resolved, any chance you recall how? I have the exact same issue where I have an EEM script that will tell the router to SCP a config upon boot.

In the debugs I'm seeing a key mismatch, but I think I've added all the correct public keys.

Thanks very much!