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Port 27018 (MongoDB shard server)

Default port of mongod running with --shardsvr.

Registered (user) port, 1024-49151 TCP Databases Do not expose to the internet

What port 27018 is used for

Default port of mongod running with --shardsvr.

Security: should port 27018 be open?

Do not expose to the internet. Same as 27017.

IANA assignment

Port 27018 is in the registered range and has no IANA assignment. The usage above is unofficial but widespread.

Check what is listening on port 27018

Linux: is anything listening on TCP 27018?
sudo ss -tlnp 'sport = :27018'
Linux / macOS: which process owns the port
sudo lsof -nP -i :27018
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':27018 '
Windows (Command Prompt)
netstat -ano | findstr :27018
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 27018 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 27018
From Windows
Test-NetConnection HOST -Port 27018

Block port 27018 in the firewall

ufw
sudo ufw deny 27018/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 27018 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 27018 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 27018' -Direction Inbound -Protocol TCP -LocalPort 27018 -Action Block

Related ports

27017MongoDB27019MongoDB config server27016chlenix27345imagepump27442jesmsjc27504kopek-httphead

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