Port 2375: Docker
Port 2375 is the Docker Engine API without TLS, giving whoever can reach it full control over every container on the host, equivalent to root access. It should only ever be bound to localhost or a trusted internal network.
| Port number | 2375 |
|---|---|
| Service | Docker daemon API (unencrypted) |
| Protocol | TCP |
| Category | Infrastructure & orchestration |
| Default encryption | No |
How do I check whether port 2375 is open?
Port 2375 carries TCP, so a connection either completes its handshake or it does not, which makes the check definitive.
| Question | Command | What to know |
|---|---|---|
| Is it open on a remote host? | nc -vz example.com 2375 | A TCP handshake either completes or it does not, so netcat gives a definitive answer in one line. |
| Same check on Windows | Test-NetConnection example.com -Port 2375 | Built into PowerShell. TcpTestSucceeded in the output is the answer; telnet is not installed by default on modern Windows. |
| What is listening locally? | ss -tlnp | grep ':2375 ' | Lists the process bound to port 2375 on Linux. On macOS use lsof -nP -iTCP:2375 -sTCP:LISTEN, on Windows netstat -ano | findstr :2375 |
Replace example.com with the host you are testing. A blocked port and a port with nothing listening on it look identical from the outside, so if a service should be running, check locally before blaming the firewall.
Frequently asked questions
What is port 2375 used for?
Port 2375 is the Docker Engine API without TLS, giving whoever can reach it full control over every container on the host, equivalent to root access. It should only ever be bound to localhost or a trusted internal network.
Is port 2375 TCP or UDP?
Port 2375 (Docker) uses TCP.
Is port 2375 secure?
Port 2375 is not encrypted by default. Where possible, use an encrypted alternative or tunnel it over TLS or a VPN.
Should I open port 2375 on my firewall?
Only if you specifically need Docker. Expose it to the smallest set of trusted sources, and never open database or Windows-service ports to the whole internet.