HP Cisco Nexus 5000 Cisco Nexus 5000 Series Switch CLI Software Configuration - Page 316

Telnet Server Configuring SSH and Telnet Be sure to have an SSH server key-pair with the appropriate version before enabling the SSH service. You can generate the SSH server key-pair according to the SSH client version used. The SSH service accepts three types of key-pairs for use by SSH version 2: • The dsa option generates the DSA key-pair for the SSH version 2 protocol. • The rsa option generates the RSA key-pair for the SSH version 2 protocol. By default, the Cisco Nexus 5000 Series switch generates an RSA key using 1024 bits. SSH supports the following public key formats: • OpenSSH • IETF Secure Shell (SECSH) Caution If you delete all of the SSH keys, you cannot start the SSH services. Telnet Server The Telnet protocol enables TCP/IP connections to a host. Telnet allows a user at one site to establish a TCP connection to a login server at another site, and then passes the keystrokes from one system to the other. Telnet can accept either an IP address or a domain name as the remote system address. The Telnet server is enabled by default on the Cisco Nexus 5000 Series switch. Guidelines and Limitations for SSH SSH has the following configuration guidelines and limitations: • The Cisco Nexus 5000 Series switch supports only SSH version 2 (SSHv2). Configuring SSH Generating SSH Server Keys You can generate an SSH server key based on your security requirements. The default SSH server key is an RSA key generated using 1024 bits. To generate SSH server keys, perform this task: Procedure Step 1 Step 2 Command or Action switch# configure terminal Purpose Enters configuration mode. switch(config)# ssh key {dsa [force] Generates the SSH server key. | rsa [bits [force]]} The bits argument is the number of bits used to generate the key. The range is 768 to 2048 and the default value is 1024. Use the force keyword to replace an existing key. Cisco Nexus 5000 Series Switch CLI Software Configuration Guide 270 OL-16597-01