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Port 4788 (xmcp)

IANA assigns port 4788 to xmcp: eXtensible Messaging Client Protocol.

Registered (user) port, 1024-49151 TCP

IANA assignment

Service nameProtoDescriptionAssigneeReference
xmcp TCP eXtensible Messaging Client Protocol
Defined TXT keys: txtvers=1 (as described in the draft) protovers=<comma-separated list of major/minor versions supported> (examples: "protovers=1.0" "protovers=1.1,2.0" Cisco -

Registry dates for this port: registered 2011-05-23, last modified 2011-10-25.

Check what is listening on port 4788

Linux: is anything listening on TCP 4788?
sudo ss -tlnp 'sport = :4788'
Linux / macOS: which process owns the port
sudo lsof -nP -i :4788
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':4788 '
Windows (Command Prompt)
netstat -ano | findstr :4788
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 4788 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 4788
From Windows
Test-NetConnection HOST -Port 4788

Block port 4788 in the firewall

ufw
sudo ufw deny 4788/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 4788 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 4788 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 4788' -Direction Inbound -Protocol TCP -LocalPort 4788 -Action Block

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