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Port 5729 (openmail)

IANA assigns port 5729 to openmail: Openmail User Agent Layer.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
openmail TCP Openmail User Agent Layer OpenMail Encyclopedi, Don Loughry -
openmail UDP Openmail User Agent Layer OpenMail Encyclopedi, Don Loughry -

Check what is listening on port 5729

Linux: is anything listening on TCP 5729?
sudo ss -tlnp 'sport = :5729'
Linux: UDP 5729
sudo ss -ulnp 'sport = :5729'
Linux / macOS: which process owns the port
sudo lsof -nP -i :5729
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':5729 '
Windows (Command Prompt)
netstat -ano | findstr :5729
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 5729 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 5729
From Windows
Test-NetConnection HOST -Port 5729
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 5729

Block port 5729 in the firewall

ufw
sudo ufw deny 5729/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 5729 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 5729 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 5729' -Direction Inbound -Protocol TCP -LocalPort 5729 -Action Block
ufw
sudo ufw deny 5729/udp
iptables
sudo iptables -A INPUT -p udp --dport 5729 -j DROP
nftables
sudo nft add rule inet filter input udp dport 5729 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 5729' -Direction Inbound -Protocol UDP -LocalPort 5729 -Action Block

Related ports

5727asgenf5728io-dist-data, io-dist-group5730unieng5741ida-discover1

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