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Port 628 (qmqp)

IANA assigns port 628 to qmqp: QMQP.

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

IANA assignment

Service nameProtoDescriptionAssigneeReference
qmqp TCP QMQP D J Bernstein -
qmqp UDP QMQP D J Bernstein -

Registry dates for this port: last modified 2018-04-05.

Check what is listening on port 628

Linux: is anything listening on TCP 628?
sudo ss -tlnp 'sport = :628'
Linux: UDP 628
sudo ss -ulnp 'sport = :628'
Linux / macOS: which process owns the port
sudo lsof -nP -i :628
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':628 '
Windows (Command Prompt)
netstat -ano | findstr :628
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 628 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 628
From Windows
Test-NetConnection HOST -Port 628
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 628

Block port 628 in the firewall

ufw
sudo ufw deny 628/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 628 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 628 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 628' -Direction Inbound -Protocol TCP -LocalPort 628 -Action Block
ufw
sudo ufw deny 628/udp
iptables
sudo iptables -A INPUT -p udp --dport 628 -j DROP
nftables
sudo nft add rule inet filter input udp dport 628 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 628' -Direction Inbound -Protocol UDP -LocalPort 628 -Action Block

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