Port 9042: Cassandra
Port 9042 is the default port for Apache Cassandra's native transport, which client drivers use to send CQL queries to the cluster. Cassandra's older Thrift interface used port 9160, now largely retired.
| Port number | 9042 |
|---|---|
| Service | Apache Cassandra native transport (CQL) |
| Protocol | TCP |
| Category | Databases |
| Default encryption | No |
How do I check whether port 9042 is open?
Port 9042 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 9042 | 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 9042 | 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 ':9042 ' | Lists the process bound to port 9042 on Linux. On macOS use lsof -nP -iTCP:9042 -sTCP:LISTEN, on Windows netstat -ano | findstr :9042 |
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 9042 used for?
Port 9042 is the default port for Apache Cassandra's native transport, which client drivers use to send CQL queries to the cluster. Cassandra's older Thrift interface used port 9160, now largely retired.
Is port 9042 TCP or UDP?
Port 9042 (Cassandra) uses TCP.
Is port 9042 secure?
Port 9042 is not encrypted by default. Where possible, use an encrypted alternative or tunnel it over TLS or a VPN.
Should I open port 9042 on my firewall?
Only if you specifically need Cassandra. Expose it to the smallest set of trusted sources, and never open database or Windows-service ports to the whole internet.