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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)

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.

logging host, ntp or snmp configured on the switch
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