to check the listening ports and applications on Linux.
Open a terminal application i.e. shell prompt.
Run any one of the following command on Linux to see open ports: $ sudo lsof -i -P -n | grep LISTEN. $ sudo netstat -tulpn | grep LISTEN. ...
For the latest version of Linux use the ss command. For example, ss -tulw.
Note that: Ports below 1024 are restricted - only apps with root privileges can listen on those. Of course, your application isn't privileged.
That's the general rule on Linux/Unix (and Android is Linux-based).
See this answer
for a rationale behind this restriction.
Ulrich Kouatang Biakoup | Technical Support