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CLI – This example enables SSH, sets the authentication parameters, and
displays the current configuration. It shows that the administrator has
made a connection via SHH, and then disables this connection.
Configuring Port Security
Port security is a feature that allows you to configure a switch port with
one or more device MAC addresses that are authorized to access the
network through that port.
When port security is enabled on a port, the switch stops learning new
MAC addresses on the specified port. Only incoming traffic with source
addresses already stored in the dynamic or static address table will be
accepted as authorized to access the network through that port. If a device
with an unauthorized MAC address attempts to use the switch port, the
intrusion will be detected and the switch can automatically take action by
disabling the port and sending a trap message.
To use port security, first allow the switch to dynamically learn the
<source MAC address, VLAN> pair for frames received on a port for an
initial training period, and then enable port security to stop address
learning. Be sure you enable the learning function long enough to ensure
that all valid VLAN members have been registered on the selected port.
Note that you can also restrict the maximum number of addresses that can
be learned by a port.
Console(config)#ip ssh server 4-47
Console(config)#ip ssh timeout 100 4-48
Console(config)#ip ssh authentication-retries 5 4-49
Console(config)#ip ssh server-key size 512 4-50
Console(config)#end
Console#show ip ssh 4-53
SSH Enabled - version 2.0
Negotiation timeout: 120 secs; Authentication retries: 3
Server key size: 768 bits
Console#show ssh 4-53
Information of secure shell
Session Username Version Encrypt method Negotiation state
------- -------- ------- -------------- -----------------
0 admin 2.0 cipher-3des session-started
Console#disconnect 0 4-23
Console#