40-2
Cisco Security Appliance Command Line Configuration Guide
OL-10088-01
Chapter 40 Managing System Access
Allowing SSH Access
Set the timeout from 1 to 1440 minutes. The default is 5 minutes. The default duration is too short in
most cases and should be increased until all pre-production testing and troubleshooting has been
completed.
For example, to let a host on the inside interface with an address of 192.168.1.2 access the security
appliance, enter the following command:
hostname(config)# telnet 192.168.1.2 255.255.255.255 inside
hostname(config)# telnet timeout 30
To allow all users on the 192.168.3.0 network to access the security appliance on the inside interface,
enter the following command:
hostname(config)# telnet 192.168.3.0 255.255.255.0 inside
Allowing SSH Access
The security appliance allows SSH connections to the security appliance for management purposes. The
security appliance allows a maximum of 5 concurrent SSH connections per context, if available, with a
maximum of 100 connections divided between all contexts.
SSH is an application running on top of a reliable transport layer, such as TCP/IP, that provides strong
authentication and encryption capabilities. The security appliance supports the SSH remote shell
functionality provided in SSH Versions 1 and 2 and supports DES and 3DES ciphers.
Note XML management over SSL and SSH are not supported.
This section includes the following topics:
• Configuring SSH Access, page 40-2
• Using an SSH Client, page 40-3
Configuring SSH Access
To configure SSH access to the security appliance, follow these steps:
Step 1 To generate an RSA key pair, which is required for SSH, enter the following command:
hostname(config)# crypto key generate rsa modulus modulus_size
The modulus (in bits) is 512, 768, 1024, or 2048. The larger the key modulus size you specify, the longer
it takes to generate an RSA. We recommend a value of 1024.
Step 2 To save the RSA keys to persistent Flash memory, enter the following command:
hostname(config)# write mem
Step 3 To identify the IP addresses from which the security appliance accepts connections, enter the following
command for each address or subnet:
hostname(config)# ssh source_IP_address mask source_interface
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