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How to bind to a port less than 1024 in Android?

Posted by: admin May 14, 2020 Leave a comment

Questions:

I have an Android service trying to bind to a server socket port 24. As it is privileged port, it is failing with a bind exception.
I am wondering what I need to do to get this working.
I see this was asked couple of times in this forum, but without a resolution.

This service runs on a device that runs on Android. We build android platform for the device. We have all the control we need.

How to&Answers:

To bind to a port less than 1024, you need to be root and there are two ways of doing that.

  1. System app : The app should be installed into /system/apps folder from where it shall be run as root. However, there are some signature issues for which help is available. Distribution is also a problem with system apps.

  2. su binary : The su binary can be invoked using a simple exec("su -c [command]"). But things are easier said than done. You need to run an android processes not just a single command. Hence, there is libsuperuser which provides you the methods and has a full-length doc page.

Answer:

This is a very similar question: Run secure API calls as root, android, though they are trying to run as root for a different reason.

That made me wonder about installing ‘system apps’, and I saw this: https://android.stackexchange.com/questions/27/rooted-how-to-install-a-system-app