pdi-communication-systems-inc/dropbear-android-build

Build tools for dropbear for Android

Dropbear for Android

Android Toolchain

This is an example for Android 5.0 on arm.

1. Get Android NDK

   curl -O https://dl.google.com/android/repository/android-ndk-r15c-linux-x86_64.zip
   unzip android-ndk-r15c-linux-x86_64.zip

2. Build the NDK

   cd android-ndk-r15c/build/tools
   ./make_standalone_toolchain.py --install-dir=../../../android-ndk --arch=arm --api=21 --deprecated-headers

3. Add the new android-ndk/bin to the $PATH

   export <full path>/android-ndk/bin:$PATH

Compiling

1. Download source

   git clone --recursive https://github.com/PDi-Communication-Systems-Inc/dropbear-android-build.git

2. Edit the HOST variables in build.sh to match your environment if required

3. Compile

   cd dropbear-android-build/dropbear
   ../build.sh <arch>

   You will find the output in dropbear-android-build/target/<arch>.
   By default it is intended to be run from /data/dropbear, this can be changed using command line arguments.

4. Running

   ln -s dropbearmulti dropbear
   ln -s dropbearmulti dropbearkey
   ln -s dropbearmulti dbclient
   ln -s dropbearmulti scp
   # Generate host key
   ./dropbearkey -f dropbear_rsa_host_key -t rsa -s 4096
   mv dropbear_rsa_host_key /system/etc/dropbear/
   # Starting server
   ./dropbear -A -N root -U 0 -G 0 -R <path of authorized_keys>

Auth

This supports encrypted passwords using crypt() Just add -e to the end of your server arguments and provide a password generated with mkpasswd -mSHA-512
Note: -e MUST be specified last. Somehow it's being reset otherwise.

SCP

For SCP to work you will need to symlink dropbearmulti to /system/xbin/scp

See Also

Description of original Android patch is here.