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Port 848 (gdoi)

IANA assigns port 848 to gdoi: GDOI.

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

IANA assignment

Service nameProtoDescriptionAssigneeReference
gdoi TCP GDOI - RFC 3547
gdoi UDP GDOI - RFC 3547

Check what is listening on port 848

Linux: is anything listening on TCP 848?
sudo ss -tlnp 'sport = :848'
Linux: UDP 848
sudo ss -ulnp 'sport = :848'
Linux / macOS: which process owns the port
sudo lsof -nP -i :848
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':848 '
Windows (Command Prompt)
netstat -ano | findstr :848
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 848 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 848
From Windows
Test-NetConnection HOST -Port 848
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 848

Block port 848 in the firewall

ufw
sudo ufw deny 848/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 848 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 848 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 848' -Direction Inbound -Protocol TCP -LocalPort 848 -Action Block
ufw
sudo ufw deny 848/udp
iptables
sudo iptables -A INPUT -p udp --dport 848 -j DROP
nftables
sudo nft add rule inet filter input udp dport 848 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 848' -Direction Inbound -Protocol UDP -LocalPort 848 -Action Block

Related ports

830netconf-ssh847dhcp-failover2853DNS over TLS / DNS over QUIC854dlep

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