Hello.
We have a Cisco Router 2911 , with IOS 15.x , it has a problem when you try to connect from the Router to the Server with SSH v.2 protocol.
Servers are Sun Solaris 10.
We have test it on Intel and Sparc platform
-Solaris 10 update 5
-Solaris 10 update 7
-Solaris 10 update 9
-Solaris 10 update 10
Test is done on next IOS-es:
c2900-universalk9-mz.SPA.150-1.M5
c2900-universalk9-mz.SPA.150-1.M8
and
c2900-universalk9-mz.SPA.151-4.M4
We have tested with DH key sizes:
(ip ssh dh min size )
1024
2048
4096
Debug on Router (debug ip ssh):
May 24 13:05:13.686 GMT: SSH CLIENT0: protocol version id is - SSH-2.0-Sun_SSH_1.1.4
May 24 13:05:13.686 GMT: SSH CLIENT0: sent protocol version id SSH-2.0-Cisco-1.25
May 24 13:05:13.686 GMT: SSH2 CLIENT 0: send:packet of length 344 (length also includes padlen of 5)
May 24 13:05:13.686 GMT: SSH2 CLIENT 0: SSH2_MSG_KEXINIT sent
May 24 13:05:13.714 GMT: SSH2 CLIENT 0: ssh_receive: 592 bytes received
May 24 13:05:13.714 GMT: SSH2 CLIENT 0: input: total packet length of 592 bytes
May 24 13:05:13.714 GMT: SSH2 CLIENT 0: partial packet length(block size)8 bytes,needed 584 bytes,
maclen 0
May 24 13:05:13.714 GMT: SSH2 CLIENT 0: input: padlength 8 bytes
May 24 13:05:13.714 GMT: SSH2 CLIENT 0: SSH2_MSG_KEXINIT received
May 24 13:05:13.714 GMT: SSH2:kex: server->client enc:aes128-cbc mac:hmac-sha1
May 24 13:05:13.714 GMT: SSH2:kex: client->server enc:aes128-cbc mac:hmac-sha1
====> This first step is OK
May 24 13:05:13.714 GMT: SSH2 CLIENT 0: send:packet of length 24 (length also includes padlen of 6)
May 24 13:05:13.714 GMT: SSH2 CLIENT 0: SSH2_MSG_KEX_DH_GEX_REQUEST sent
May 24 13:05:13.714 GMT: SSH2 CLIENT 0: Range sent- 1024 < 2048 < 4096
May 24 13:05:13.718 GMT: SSH2 CLIENT 0: ssh_receive: 424 bytes received
May 24 13:05:13.718 GMT: SSH2 CLIENT 0: input: total packet length of 424 bytes
May 24 13:05:13.718 GMT: SSH2 CLIENT 0: partial packet length(block size)8 bytes,needed 416 bytes,
maclen 0
May 24 13:05:13.718 GMT: SSH2 CLIENT 0: input: padlength 10 bytes
May 24 13:05:13.718 GMT: SSH2 CLIENT 0: SSH2_MSG_KEX_DH_GEX_GROUP received
May 24 13:05:13.718 GMT: SSH2 CLIENT 0: Server has chosen 3192 -bit dh keys
==> Sun Solaris side choose wrong size (3192) every time , on every Solaris we tested
May 24 13:05:13.718 GMT: %SSH-3-INV_MOD: Invalid modulus length
May 24 13:05:13.718 GMT: SSH CLIENT0: Session disconnected - error 0x00
Interesting thing is that SSH to any other Linux/Unix (except Solaris) is working.
Debug of working ssh to Linux server:
ay 24 13:09:54.967 GMT: SSH CLIENT0: protocol version id is - SSH-2.0-OpenSSH_5.5p1 Debian-4ubuntu5
May 24 13:09:54.967 GMT: SSH CLIENT0: sent protocol version id SSH-2.0-Cisco-1.25
May 24 13:09:54.967 GMT: SSH2 CLIENT 0: send:packet of length 344 (length also includes padlen of 5)
May 24 13:09:54.967 GMT: SSH2 CLIENT 0: SSH2_MSG_KEXINIT sent
May 24 13:09:54.971 GMT: SSH2 CLIENT 0: ssh_receive: 536 bytes received
May 24 13:09:54.971 GMT: SSH2 CLIENT 0: input: total packet length of 784 bytes
May 24 13:09:54.971 GMT: SSH2 CLIENT 0: partial packet length(block size)8 bytes,needed 776 bytes,
maclen 0
May 24 13:09:54.971 GMT: SSH2 CLIENT 0: ssh_receive: 248 bytes received
May 24 13:09:54.971 GMT: SSH2 CLIENT 0: partial packet length(block size)8 bytes,needed 776 bytes,
maclen 0
May 24 13:09:54.971 GMT: SSH2 CLIENT 0: input: padlength 10 bytes
May 24 13:09:54.971 GMT: SSH2 CLIENT 0: SSH2_MSG_KEXINIT received
May 24 13:09:54.971 GMT: SSH2:kex: server->client enc:aes128-cbc mac:hmac-sha1
May 24 13:09:54.971 GMT: SSH2:kex: client->server enc:aes128-cbc mac:hmac-sha1
====> This first step is OK
May 24 13:09:54.971 GMT: SSH2 CLIENT 0: send:packet of length 24 (length also includes padlen of 6)
May 24 13:09:54.971 GMT: SSH2 CLIENT 0: SSH2_MSG_KEX_DH_GEX_REQUEST sent
May 24 13:09:54.971 GMT: SSH2 CLIENT 0: Range sent- 1024 < 2048 < 4096
May 24 13:09:54.975 GMT: SSH2 CLIENT 0: ssh_receive: 280 bytes received
May 24 13:09:54.975 GMT: SSH2 CLIENT 0: input: total packet length of 280 bytes
May 24 13:09:54.975 GMT: SSH2 CLIENT 0: partial packet length(block size)8 bytes,needed 272 bytes,
maclen 0
May 24 13:09:54.975 GMT: SSH2 CLIENT 0: input: padlength 8 bytes
May 24 13:09:54.975 GMT: SSH2 CLIENT 0: SSH2_MSG_KEX_DH_GEX_GROUP received
May 24 13:09:54.975 GMT: SSH2 CLIENT 0: Server has chosen 2048 -bit dh keys
May 24 13:09:55.031 GMT: SSH2 CLIENT 0: send:packet of length 272 (length also includes padlen of 6)
May 24 13:09:55.031 GMT: SSH2 CLIENT 0: expecting SSH2_MSG_KEX_DH_GEX_REPLY
May 24 13:09:55.115 GMT: SSH2 CLIENT 0: ssh_receive: 536 bytes received
May 24 13:09:55.115 GMT: SSH2 CLIENT 0: input: total packet length of 832 bytes
May 24 13:09:55.115 GMT: SSH2 CLIENT 0: partial packet length(block size)8 bytes,needed 824 bytes,
maclen 0
May 24 13:09:55.115 GMT: SSH2 CLIENT 0: ssh_receive: 312 bytes received
May 24 13:09:55.115 GMT: SSH2 CLIENT 0: partial packet length(block size)8 bytes,needed 824 bytes,
maclen 0
May 24 13:09:55.115 GMT: SSH2 CLIENT 0: input: padlength 8 bytes
May 24 13:09:55.115 GMT: SSH2 CLIENT 0: SSH2_MSG_KEX_DH_GEX_REPLY received
May 24 13:09:55.115 GMT: SSH2 CLIENT 0: Skipping ServerHostKey Validation
May 24 13:09:55.195 GMT: SSH2 CLIENT 0: signature length 271
May 24 13:09:55.195 GMT: SSH2: kex_derive_keys complete
====> This second step is OK
Configuration of SSH server ( /etc/ssh/sshd_config ) is similar to one on other (working) Linux systems
Then we try to force key size in SSH Daemon config :
For example :
ServerKeyBits 2048
But then again it select key size of 3192 and connection error is the same.
Please help.
BR,
Hrvoje.
