These libraries do not need to match with the ones in the real /lib. While this environment is in place, we can easily add or remove libraries to check for dependencies or compatibility.

Access to the SSH-server in the jail can be done using the same IP and the port that Dropbear is listening on. The root filesystem for dropbear is actually /chroot/jail. How I see this graphically, if it could help:Īs you can see, Dropbear will be running under the chroot jail.

The name itself actually tells you what it is, it runs processes under a changed root (a subdirectory of the original root). A chroot jail is an isolated environment running on top of another one. I chose to use an existing installation and start my test-environment in a chroot jail. One of the options would be to build a small system from scratch. BusyBox is a single executable that contains alternatives for common Linux utilities.

Since you do need a shell, BusyBox seemed to be a good choice. My goal was to create a Linux system that was accessible via SSH (it had to be Dropbear, an alternative to OpenSSH-server) and to have as less as possible libraries in it. Using this setup gives you the flexibility to experiment with a minimal environment without rebuilding small Linux images.įirst of all, it might be a good idea to elaborate a little more on the setup. Probably this setup is quite useless for daily use but it can be used as a base for testing with a minimum set of libraries available. For some testing, I needed a minimal environment containing only a BusyBox shell and that was accessible via Dropbear SSH-server. This was the case which lead to this post. Sometimes you just need some kind of setup which is not so standard.

Dropbear ssh for mac os x iphone 6