ccna 200-301 official cert guide book

ccna 200-301 official cert guide book.2.1.4.2 Configuring SSHUsing the CLI, a Cisco router can be configured to support SSH in four stepso Step 1 If the router already has a unique host name, use the ip domain-name domain-name command in global configuration mode to configure the IP domain name of the network.Step 2 To encrypt SSH traffic, the router must generate a one-way key. This key is called an asymmetric key. Cisco IOS software uses the Rivest, Shamir, and Adleman (RSA) algorithms to generate the key. In global configuration mode, RSA keys are created with the cryptokeygenerate rsageneral-keysmodulusmodulus-size command. The modulus determines the number of bits of the RSA key and can be selected in the range of 360.2048 bits. The larger the modulus, the more secure the RSA key. However, the larger the modulus value, the longer the generation time and the time to encrypt and decrypt. The recommended minimum length of the modulus value is 1024 bits.Note: & After generating the RSA, SSH is automatically enabled. step 3 Make sure you have a valid local database username entry. If not, create it with the username name secret secret command.Step 4 Start a vty inbound to SSH session using the line vty command loginlocal and transport inputssh. To verify SSH and display the resulting key, use the show crypto key mypubkey rsa command in privileged EXEC mode. If a key pair exists, it is recommended that you use the crypto key zeroize rsa command to override it first.2.1.4.3 Optional SSH CommandsThe optional SSH command can be used to complete the following configurations.SSH version.SSH expiration time; Number of authentication attempts. The Cisco router supports the following two versions of SSHoSSH version 1 (SSHvl): the original version, but with known vulnerabilities.