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Port 847 (dhcp-failover2)

IANA assigns port 847 to dhcp-failover2: dhcp-failover 2.

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

IANA assignment

Service nameProtoDescriptionAssigneeReference
dhcp-failover2 TCP dhcp-failover 2 Bernard Volz -
dhcp-failover2 UDP dhcp-failover 2 Bernard Volz -

Check what is listening on port 847

Linux: is anything listening on TCP 847?
sudo ss -tlnp 'sport = :847'
Linux: UDP 847
sudo ss -ulnp 'sport = :847'
Linux / macOS: which process owns the port
sudo lsof -nP -i :847
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':847 '
Windows (Command Prompt)
netstat -ano | findstr :847
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 847 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 847
From Windows
Test-NetConnection HOST -Port 847
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 847

Block port 847 in the firewall

ufw
sudo ufw deny 847/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 847 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 847 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 847' -Direction Inbound -Protocol TCP -LocalPort 847 -Action Block
ufw
sudo ufw deny 847/udp
iptables
sudo iptables -A INPUT -p udp --dport 847 -j DROP
nftables
sudo nft add rule inet filter input udp dport 847 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 847' -Direction Inbound -Protocol UDP -LocalPort 847 -Action Block

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