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show udp port 18999?

I noticed udp/18999 is always listed in #show udp even if no IP is configured

as1r3#show udp
Proto Remote Port Local Port In Out Stat TTY OutputIF
17 0.0.0.0 0 172.16.254.13 18999 0 0 11 0

What's so special about UDP/18999? Is this the first ephemeral UDP port IOS uses? What is this (dummy?) entry for?

IOS 15.6(1)T

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Enthusiast

I have the same. Anyone knows what the Server Service is?

TEST#show control-plane host open-ports
Active internet connections (servers and established)
Prot               Local Address             Foreign Address                  Service    State
 tcp                        *:23                         *:0                   Telnet   LISTEN
 udp                     *:18999                         *:0     udp_transport Server   LISTEN
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Just found — it’s described as a Cisco bug CSCuz54118 — UDP transport Server socket open by default.

Workaround: Use an ACL to block UDP traffic destined to UDP port 18999.

 

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