A network engineer is troubleshooting secure remote management access on an enterprise router named EDGE-RTR-01. The router is currently permitting remote sessions, but output verification shows that SSH version 1.5 is active instead of SSH version 2.
The engineer gathers the following CLI output from EDGE-RTR-01:
text
EDGE-RTR-01# show ip ssh
SSH Enabled - version 1.5
Authentication timeout: 120 secs; Authentication retries: 3
EDGE-RTR-01# show running-config | include crypto key
crypto key generate rsa modulus 512
Which configuration change must be performed on EDGE-RTR-01 to support and enforce SSH version 2?
- Re-generate the RSA key pair using a modulus size of at least 768 bits and execute the command ip ssh version 2.Cevap
- BConfigure the line vty configuration mode with the command transport input ssh v2.
- CConfigure a domain name using the ip domain-name command and restart the SSH process using service ssh restart.
- DAdd the overload keyword to the crypto key generate rsa command to force 2048-bit encryption.
Cevap
Re-generate the RSA key pair using a modulus size of at least 768 bits and execute the command ip ssh version 2.
In Cisco IOS, SSH version 2 requires an RSA key pair with a minimum length of 768 bits. When a key size under 768 bits (such as 512 bits) is generated, Cisco IOS defaults to SSH version 1.5. Re-generating the key with a length of at least 768 bits (or 1024/2048 bits) and issuing 'ip ssh version 2' enables and enforces SSHv2.
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SSH Version 2 RSA Key Size Prerequisites