Cisco – get a timeout when I connect via ssh to a Cisco ASA, even though management and ACLs are configured

ciscocisco-asassh

I set up a Cisco ASA 5505 8.4(3), and

  • specified ssh version 2
  • enabled ssh access to the WAN interface via ssh <my network> <mask> <WAN interface>
  • allowed ssh from my network via an ACL
  • my user account has privilege 15 with full access, including ssh

I did similarly for ASDM and it worked. However, when connection via ssh, I get:

ssh: connect to host <name> port 22: Connection timed out

I checked the log via the ASDM, which confirmed that there's a connection, but ending with an error message:

SSH session from on interface for user ""
disconnected by SSH server, reason: "Internal error" (0x00)

How can it be fixed?

Best Answer

Unfortunately the ASA doesn't show a good explanation in the error message. It's required to create an RSA key on the ASA, either via console or command line in the ASDM, executing the command crypto key generate rsa, for example with highest possible modulus size:

crypto key generate rsa modulus 2048

in global configuration mode. The default modulus would be 1024.

With the ASDM it can also be done in the configuration menu, device management, identity certificates, add, new:

ASDM key generation

Since the other requirements were already met, the connection should be successful.

Since I cannot add images to comments to the question above, here a screenshot about mass bumping comment spam starting with one to this question and answer. That's a screenshot of moderator activity, no action by me.

comment spam

Related Topic