Remote System Management

An administrator does not have to be physically connected to the console port of Cisco ASA to be able to access the CLI. The security Cisco ASA supports three remote management protocols:

• Telnet
• Secure Shell (SSH)
• SSL (ASDM)

Telnet

The security Cisco ASA comes with a Telnet server that allows users to remotely manage it. Set up a Telnet server by choosing Configuration > Features > Device Administration > Administration > Telnet. Click Add and specify the IP host, subnet, and network addresses allowed to connect from a particular interface. In Figure 18-18, the entire 192.168.10.0/24 inside network is allowed to start a Telnet connection to the security Cisco ASA.

Figure 18-18. Setting Up the Telnet Server

To monitor the Telnet sessions that are being established to the security Cisco ASA, choose Monitoring > Features > Administration > Telnet Sessions. This screen shows the session ID and the IP address of the Telnet client, as shown in Figure 18-19, where a workstation is accessing the security Cisco ASA from 192.168.10.2.

Figure 18-19. Monitoring the Telnet Sessions

Note

Because the security Cisco ASA supports Telnet and SSH, using SSH for remote management is highly recommended.

SSH

The security Cisco ASA can act as an SSH server to allow secured connections. The SSH server can be enabled by choosing Configuration > Features > Device Administration > Administration > Secure Shell. Click Add and specify the IP host, subnet, and network addresses allowed to connect from a particular interface. In Figure 18-20, the inside network of 192.168.10.0/24 and mgmt subnet of 172.18.124.0/24 are allowed to start an SSH connection to the security Cisco ASA. Cisco ASA is allowed to accept only SSH version 2 connections.

Figure 18-20. Setting Up the SSH Server

Example 18-8 shows the related configuration.

Example 18-8. Setting Up the SSH Server via the CLI

ssh version 2 ssh 192.168.10.0 255.255.255.0 inside ssh 172.18.124.0 255.255.255.0 mgmt

SSL (ASDM)

The remote administration of Cisco ASA also includes managing it from ASDM. You can limit the IP addresses to manage the security Cisco ASA by setting the parameters under Configuration > Features > Device Administration > Administration > ASDM/HTTPS. In Figure 18-21, the 172.18.124.0/24 subnet is allowed to establish ASDM connections from the mgmt interface.

Figure 18-21. Managing ASDM

Caution

If the HTTP server is disabled, ASDM will stop communicating with Cisco ASA.