What's listening on port 8080

Today, while experimenting with CockroachDB I noticed that a process was already listening on TCP port 8080. I used netstat — which I had to install first — to discover which process was listening on port 8080.

The fact that I had to install netstat on Ubuntu 19.04 led me to conclude that there was an alternative command to get the same information, and indeed: ss, another utility to investigate sockets according to its man page.

In the evening I used

ss -lptn

to find the names of all TCP listening processes.

The options I used (combined) are:

-l, --listening: Display only listening sockets.
-p, --processes: Show process using socket.
-t, --tcp: Display TCP sockets.
-n, --numeric: Do not try to resolve service names.

Regarding the latter, this shows 8080 instead of http-alt for port 8080.

Since I wanted to keep that process listening on port 8080 running I had to find an alternative port for CockroachDB, which can be specified with the --http-addr option as follows:

cockroach start \
    --certs-dir=$CERTS \
    --listen-addr=localhost \
    --http-addr=localhost:8200