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?

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    Aug 9, 2017 at 15:42
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2 Answers 2


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

  • Whereas other OS's auto generate keys when the SSH daemon is started, or in the case of a client the first time you try and connect unfortunately the ASA software doesn't give you any pointers or generate one automatically. May 30, 2013 at 21:11
  • 2
    well the Cisco IOS doesn't automatically generate the SSH cert either. you also need to type #crypto key generate rsa modulus 2048 then you can type $ip ssh version 2
    – knotseh
    May 30, 2013 at 21:26
  • 1
    technically, it shouldn't enable ssh unless it has a valid cert. I've never seen one start sshd without a cert.
    – Ricky
    May 30, 2013 at 23:17
  • 1
    I beat my head against this every time I deploy a new ASA. I always forget that everything looks fine in the config, but until you generate the RSA key it looks like an ACL issue. May 31, 2013 at 18:38
  1. asa(config)# crypto key generate rsa general-keys modulus 2048

    If you don't have user accounts already then configure below two line 2-3.

  2. asa(config)# username ash password ash privi 15

  3. asa(config)# enable password cisco123

    To Allow Access from inside network

  4. asa(config)# ssh inside (To Allow anyone from inside)

    To Allow Access from outside network

  5. asa(config)# ssh outside (To Allow anyone from Outside)

    the system should know where your useraccounts are: For lookup in Local Database

  6. asa(config)# aaa authentication ssh console LOCAL ------ Case sensitive (LOCAL must be in capital, not Local or local)

  7. asa(config)# ssh version 2

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