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Nexus 5000 VLAN interface - portscan shows unknown UDP port 11297 open/filtered

A Nexus 5010 running NX/OS 5.0(2)N2(1) with the following features

no feature telnet
no telnet server enable
no feature http-server
feature tacacs+
cfs eth distribute
feature udld
feature interface-vlan
feature lacp
feature lldp
feature fex

and an active NTP and SNMP-Server v2c and v3 config as well as one VLAN1 interface configured for inband-mgmt:

interface Vlan1
   no shutdown
   no ip redirects
   ip address 10.1.2.3/24

Shows an unexpected unknown open or filtered UDP port in a Portscan:

# nmap -sU -v -P0 10.1.2.3 -p 0-65535

...
Not shown: 65531 closed ports
PORT      STATE         SERVICE
67/udp    open|filtered dhcps
68/udp    open|filtered dhcpc
123/udp   open|filtered ntp
161/udp   open|filtered snmp
11297/udp open|filtered unknown


How can i find out what caused this port to be either open (what service?) or filtered (what ACL/implied filter?)

Juergen

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