02-03-2016 10:06 AM - edited 03-01-2019 05:50 PM
I've found this question has been asked many times on the web and in the Cisco forums. But I've never found an answer. I'm hoping that someone out there has the answer hidden in their back pocket.
The question:
How do you disable IPv6 listening ports in a Cisco IOS router?
With absolutely no IPv6 configuration on a router, the listening ports are created when SNMP communities or NTP are configured. This symptom exists across several Cisco platforms (6500, 3700, 2800 to name a few) and IOS versions.
Example:
(The following is the complete output from a test device.)
router#show ip sockets | include ^P|v6 !Notice no ports listening from this command!
Proto Remote Port Local Port In Out Stat TTY OutputIF
router#
router#config t
Enter configuration commands, one per line. End with CNTL/Z.
router(config)#snmp-server community test
router(config)#end
router#show ip sockets | include ^P|v6
Proto Remote Port Local Port In Out Stat TTY OutputIF
17(v6) --listen-- --any-- 161 0 0 20001 0
17(v6) --listen-- --any-- 162 0 0 20011 0
17(v6) --listen-- --any-- 59017 0 0 20001 0
router#
router#
router#config t
Enter configuration commands, one per line. End with CNTL/Z.
router(config)#ntp server 1.1.1.1
router(config)#end
router#
router#show ip sockets | include ^P|v6
Proto Remote Port Local Port In Out Stat TTY OutputIF
17(v6) --listen-- --any-- 161 0 0 20001 0
17(v6) --listen-- --any-- 162 0 0 20011 0
17(v6) --listen-- --any-- 59017 0 0 20001 0
17(v6) --listen-- --any-- 123 0 0 20001 0
What is not the answer:
Possible answers: