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Port 5755 (openmailg)

IANA assigns port 5755 to openmailg: OpenMail Desk Gateway server.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
openmailg TCP OpenMail Desk Gateway server OpenMail Encyclopedi, Don Loughry -
openmailg UDP OpenMail Desk Gateway server OpenMail Encyclopedi, Don Loughry -

Check what is listening on port 5755

Linux: is anything listening on TCP 5755?
sudo ss -tlnp 'sport = :5755'
Linux: UDP 5755
sudo ss -ulnp 'sport = :5755'
Linux / macOS: which process owns the port
sudo lsof -nP -i :5755
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':5755 '
Windows (Command Prompt)
netstat -ano | findstr :5755
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 5755 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 5755
From Windows
Test-NetConnection HOST -Port 5755
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 5755

Block port 5755 in the firewall

ufw
sudo ufw deny 5755/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 5755 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 5755 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 5755' -Direction Inbound -Protocol TCP -LocalPort 5755 -Action Block
ufw
sudo ufw deny 5755/udp
iptables
sudo iptables -A INPUT -p udp --dport 5755 -j DROP
nftables
sudo nft add rule inet filter input udp dport 5755 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 5755' -Direction Inbound -Protocol UDP -LocalPort 5755 -Action Block

Related ports

5748tunalyzer5750rscd5757x500ms5766openmailns

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