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Port 218 (mpp)

IANA assigns port 218 to mpp: Netix Message Posting Protocol.

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

IANA assignment

Service nameProtoDescriptionAssigneeReference
mpp TCP Netix Message Posting Protocol Shannon Yeh -
mpp UDP Netix Message Posting Protocol Shannon Yeh -

Check what is listening on port 218

Linux: is anything listening on TCP 218?
sudo ss -tlnp 'sport = :218'
Linux: UDP 218
sudo ss -ulnp 'sport = :218'
Linux / macOS: which process owns the port
sudo lsof -nP -i :218
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':218 '
Windows (Command Prompt)
netstat -ano | findstr :218
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 218 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 218
From Windows
Test-NetConnection HOST -Port 218
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 218

Block port 218 in the firewall

ufw
sudo ufw deny 218/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 218 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 218 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 218' -Direction Inbound -Protocol TCP -LocalPort 218 -Action Block
ufw
sudo ufw deny 218/udp
iptables
sudo iptables -A INPUT -p udp --dport 218 -j DROP
nftables
sudo nft add rule inet filter input udp dport 218 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 218' -Direction Inbound -Protocol UDP -LocalPort 218 -Action Block

Related ports

216CAIlic217dbase219uarps220imap3

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