06-12-2020 01:24 AM
hi,
just a sanity check here.
is it safe to issue 'ip ssh version 2'? will it "break" or lock me out of the router?
all VTY lines only allows SSH.
Router#show ip ssh
SSH Enabled - version 1.99
06-12-2020 01:40 AM
Hello @johnlloyd_13 ,
it should be safe you just need to use recent client software for Putty or SecureCRT that support SSH version 2 that is considered more secure.
When you do the test do not close the original vty session and try to open an additional window to verify the new settings and the ability to access the device.
Hope to help
Giuseppe
06-12-2020 02:57 AM
Hi,
It is safe but you must fulfill requirements as ssh client must be updated that can support all required encryption algorithms.
06-16-2020 10:46 AM - edited 06-16-2020 10:48 AM
router#show ip ssh
SSH Enabled - version 2.0 Authentication methods:publickey,keyboard-interactive,password Authentication Publickey Algorithms:x509v3-ssh-rsa,ssh-rsa Hostkey Algorithms:x509v3-ssh-rsa,ssh-rsa Encryption Algorithms:aes128-ctr,aes192-ctr,aes256-ctr MAC Algorithms:hmac-sha2-256,hmac-sha2-512,hmac-sha1,hmac-sha1-96
KEX Algorithms:diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1 Authentication timeout: 120 secs; Authentication retries: 3 Minimum expected Diffie Hellman key size : 2048 bits
To see what algorithms your device(s) support. Make sure one of these is listed in the SSH client you are using. More than likely it is, but can't hurt to check.
06-16-2020 02:40 PM - edited 06-16-2020 02:50 PM
Hello
No it won't lock you out of your current session or future session from any terminal emulation software but it could for future ssh sessions between network devices - such has switch to switch or router etc..running different versions
One thing i am aware of from very recently is if you change
the the ssh authentication/mac algorithms then that can and does lock you out of future sessions from switch to switch or router etc but again not from any terminal emulation software
Discover and save your favorite ideas. Come back to expert answers, step-by-step guides, recent topics, and more.
New here? Get started with these tips. How to use Community New member guide