HTTPfy

Port 861 (owamp-control, owamp-test)

IANA assigns port 861 to owamp-control, owamp-test: OWAMP-Control.

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

IANA assignment

Service nameProtoDescriptionAssigneeReference
owamp-control TCP OWAMP-Control IESG RFC 4656
owamp-test UDP OWAMP-Test IESG RFC 8545

Registry dates for this port: last modified 2018-12-21.

Check what is listening on port 861

Linux: is anything listening on TCP 861?
sudo ss -tlnp 'sport = :861'
Linux: UDP 861
sudo ss -ulnp 'sport = :861'
Linux / macOS: which process owns the port
sudo lsof -nP -i :861
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':861 '
Windows (Command Prompt)
netstat -ano | findstr :861
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 861 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 861
From Windows
Test-NetConnection HOST -Port 861
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 861

Block port 861 in the firewall

ufw
sudo ufw deny 861/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 861 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 861 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 861' -Direction Inbound -Protocol TCP -LocalPort 861 -Action Block
ufw
sudo ufw deny 861/udp
iptables
sudo iptables -A INPUT -p udp --dport 861 -j DROP
nftables
sudo nft add rule inet filter input udp dport 861 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 861' -Direction Inbound -Protocol UDP -LocalPort 861 -Action Block

Related ports

854dlep860iscsi862twamp-control, twamp-test873rsync daemon

All port numbers · Open port checker
Assignment data: IANA port number registry (public domain), retrieved 2026-11-10.