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Cisco Bug: CSCvi52134 - "Show ip sockets" lists ipv6 listeners even without ipv6 config

Last Modified

May 31, 2018

Products (1)

  • Cisco IOS

Known Affected Releases

Denali-16.3.3 Denali-16.3.6

Description (partial)

Symptom:
Without ipv6 enabled on the switch (no ipv6 interface, no "ipv6 routing" )
with ipv4 syslog, ntp and SNMP configured we are able to see:

WS-C3650-24TS-S#show ip sockets  | i v6
 17(v6)   --listen--          --any--           161   0   0 2020001   0 
 17(v6)   --listen--          --any--           162   0   0 2020011   0 
 17(v6)   --listen--          --any--         49500   0   0 2020001   0 
 17(v6)   --listen--          --any--           123   0   0 2020001   0 

Actually, range can be 1025 - 65535.
Any of features enables SW listening to ipv6 port.
If no ipv6 configured, these ports are not actually exposed to the rest of the network and are not available.

Conditions:
logging host, ntp or snmp configured on the switch
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