KB ID 0001322

1. Crypto Key Generate Rsa 2048
2. Crypto Key Generate Rsa
3. Generate A Rsa Crypto Key
4. Crypto Key Generate Rsa Cisco

Problem

I’ve lost count of the number of times this has happened to me! Most of my colleagues prefer to use the ASDM for remote management, but if (like me) you work at command line, then sometimes people <ahem> forget to generate the RSA keypair when deploying a firewall. Then even if SSH access and AAA is setup correctly, you still can’t get in via SSH. Instead you see the following;

RoyalTS and RoyalTSX: ssh_exchange_identification: Connection closed by remote host.

Crypto Key Generate Rsa 2048

I guess the other option is to go Tools - Command Line Interface. And issue the command: 'crypto key generate rsa modulus 1024 noconfirm' View solution in original post. When you use the crypto key generate rsa command, it will ask you how many bits you want to use for the key size. How much should you pick? It’s best to check the next generation encryption article from Cisco for this. At this moment, a key size of 2048 bits is acceptable. Key sizes of 1024 or smaller should be avoided. How I create RSA key and enable SSH access in Cisco VG202, in a Cisco router I use the next commands(but in a VG not exists): conf t. Crypto key generate rsa modulus 1024 ip domain-name domain-name ip ssh version 2 ip ssh time-out 120 ip ssh authentication-retries 3 line vty 0 4 transport input telnet ssh end.

PuTTY: PuTTY Fatal Error: Server unexpectedly closed network connection.

SecureCRT: Connection closed.

OSX/Linux: ssh_exchange_identification: Connection closed by remote host.

Now at command line you can fix this with a ‘Crypto Key Generate RSA Modulus 2048‘ command, but you can’t get to command line only ASDM.

Solution

On older versions of the ASDM you could generate the keypair in the Identification Certificates section (well you still can but only if you are also generating a certificate request file). So, as we are command line warriors, lets use the ASDM’s command line!

Crypto Key Generate Rsa

Tools > Command Line Interface > Multiple Line

Send > Wait a couple of minutes and try again.

Generate A Rsa Crypto Key

REMEMBER: I’m assuming you have SSH setup correctly if not, see the following article;

Related Articles, References, Credits, or External Links

Crypto Key Generate Rsa Cisco

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