similar to icanhazip.com
$ ip-server
listening on 0.0.0.0:8000
Now that the server is running on port 8000, we can connect via ip-server or an HTTP client with a GET request
$ ip-server --client localhost:8000
127.0.0.1
$ curl localhost:8000
127.0.0.1
$ firefox localhost:8000
-h, --help
print help
#
-v, --version
print version
#
-c, --client <address>
run as client, connect to address
client will print remote address to stdout with a newline
make sure to use fully qualified hostname and port (e.g. localhost:8000 instead of localhost)
#
-s, --server <address>
run as server, bind to address (default 0.0.0.0:8000)
server will handle both ip-server -c and HTTP GET requests (like from curl)
server will also print client addresses to stdout with a newline