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Port 687 (asipregistry)

IANA assigns port 687 to asipregistry.

Well-known (system) port, 0-1023 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
asipregistry TCP asipregistry Erik Sea -
asipregistry UDP asipregistry Erik Sea -

Check what is listening on port 687

Linux: is anything listening on TCP 687?
sudo ss -tlnp 'sport = :687'
Linux: UDP 687
sudo ss -ulnp 'sport = :687'
Linux / macOS: which process owns the port
sudo lsof -nP -i :687
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':687 '
Windows (Command Prompt)
netstat -ano | findstr :687
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 687 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 687
From Windows
Test-NetConnection HOST -Port 687
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 687

Block port 687 in the firewall

ufw
sudo ufw deny 687/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 687 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 687 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 687' -Direction Inbound -Protocol TCP -LocalPort 687 -Action Block
ufw
sudo ufw deny 687/udp
iptables
sudo iptables -A INPUT -p udp --dport 687 -j DROP
nftables
sudo nft add rule inet filter input udp dport 687 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 687' -Direction Inbound -Protocol UDP -LocalPort 687 -Action Block

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Assignment data: IANA port number registry (public domain), retrieved 2026-11-10.