To de?¬?ne a customized banner to be displayed before the username and password login
prompts, you can use the banner login command in global con?¬?guration mode. To disable
the login banner, you can use the no banner login command.
When you enter the banner login command, follow the command with one or more blank
spaces and a delimiting character. After the banner text has been added, terminate the
message with the same delimiting character.
Telnet and SSH Access
Telnet is the most common method of accessing a network device. However, Telnet is an
insecure way of accessing a network. SSH is a secure replacement for Telnet that gives the
same type of access. Communication between the client and server is encrypted in both
WARNING Be careful when selecting the words that are used in the login banner.
Words like welcome can imply that access is not restricted and allow a hacker to defend
his actions.
308 Chapter 4: LAN Connections
SSH version 1 and SSH version 2. Implement SSH version 2, if possible, because it uses a
more enhanced security encryption algorithm. When encryption is enabled, a Rivest,
Shamir, and Adleman (RSA) encryption key must be generated on the router. In addition,
an IP domain must be assigned to the router.
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