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The Cisco switch must be configured to disable the auxiliary port unless it is connected to a secured modem providing encryption and authentication.


Finding ID Version Rule ID IA Controls Severity
V-221006 CISC-RT-000230 SV-221006r622190_rule Low
The use of POTS lines to modems connecting to network devices provides clear text of authentication traffic over commercial circuits that could be captured and used to compromise the network. Additional war dial attacks on the device could degrade the device and the production network. Secured modem devices must be able to authenticate users and must negotiate a key exchange before full encryption takes place. The modem will provide full encryption capability (Triple DES) or stronger. The technician who manages these devices will be authenticated using a key fob and granted access to the appropriate maintenance port; thus, the technician will gain access to the managed device. The token provides a method of strong (two-factor) user authentication. The token works in conjunction with a server to generate one-time user passwords that will change values at second intervals. The user must know a personal identification number (PIN) and possess the token to be allowed access to the device.
Cisco IOS XE Switch RTR Security Technical Implementation Guide 2023-09-13


Check Text ( C-22721r408812_chk )
Review the configuration and verify that the auxiliary port is disabled unless a secured modem providing encryption and authentication is connected to it.

line aux 0
no exec

Note: Transport input none is the default; hence it will not be shown in the configuration.

If the auxiliary port is not disabled or is not connected to a secured modem when it is enabled, this is a finding.
Fix Text (F-22710r408813_fix)
Disable the auxiliary port.

SW2(config)#line aux 0
SW2(config-line)#no exec
SW2(config-line)#transport input none