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Port 4868 (phrelay)

IANA assigns port 4868 to phrelay: Photon Relay.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
phrelay TCP Photon Relay - -
phrelay UDP Photon Relay - -

Check what is listening on port 4868

Linux: is anything listening on TCP 4868?
sudo ss -tlnp 'sport = :4868'
Linux: UDP 4868
sudo ss -ulnp 'sport = :4868'
Linux / macOS: which process owns the port
sudo lsof -nP -i :4868
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':4868 '
Windows (Command Prompt)
netstat -ano | findstr :4868
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 4868 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 4868
From Windows
Test-NetConnection HOST -Port 4868
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 4868

Block port 4868 in the firewall

ufw
sudo ufw deny 4868/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 4868 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 4868 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 4868' -Direction Inbound -Protocol TCP -LocalPort 4868 -Action Block
ufw
sudo ufw deny 4868/udp
iptables
sudo iptables -A INPUT -p udp --dport 4868 -j DROP
nftables
sudo nft add rule inet filter input udp dport 4868 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 4868' -Direction Inbound -Protocol UDP -LocalPort 4868 -Action Block

Related ports

4851derby-repli4867unify-debug4869phrelaydbg4870cc-tracking

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