ubiquiti / dropbear-android Goto Github PK

Dropbear version 2018.76 cross-compiled to run on Android with password authentication

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dropbear-android's Introduction

Android Dropbear

A patch set and script to download and cross-compile Dropbear SSH server for use on Android with password authentication. As the 64-bit binaries don't seem to work reliably, this project is configured to compile 32-bit binaries using the Android NDK toolchain.

Generated binares will all be PIE (position indepedent executable) binaries as it is required on Android 5 (L/ollipop).

If building for android < 4.1 then before building, issue:

export DISABLE_PIE=1

Building Dropbear for Android

The process consists of just four parts:

Specify the version of Dropbear you'd like to download and crosscompile. Open build-android-dropbear.sh and change the value of VERSION at the top, which defaults to 2018.76
Build your standalone android toolchain.
See the android developer site for more info: https://developer.android.com/ndk/guides/standalone_toolchain.html
Export your toolchain's location:

export TOOLCHAIN=/path/to/standalone/toolchain

Run the build script:

./build-dropbear-android.sh

Generated binaries will be outputted to {android dropbear repo directory}/target/arm

Customizations

Much of the project is pre-configured with sane defaults, but if you'd like to customize the behavior of Dropbear for Android, here are a few tips.

To change/configure most options, look in and modify the following files as appropriate:
a) default_options.h
b) sysoptions.h
c) config.h

For instance, to change the port Dropbear runs on or to change the default location in which Dropbear tries to generate keys, edit default_options.h and modify the respective values.

Basic usage

Dropbear for Android adds a few special flags to Dropbear:

A: signifies Android mode and allows for password authentication in the absence of the crypt() lib
G: allows us to specify the GID dropbear should run as
U: allows us to specify the UID dropbear should run as
N: specify the login username for the session
T: specify the authentication key for the session

A typical usecase would be:

./dropbear -d /path/to/dropbear_dss_host_key -r /path/to/dropbear_rsa_hostkey -p 10022 -P /path/to/dropbear.pid -R -A -N user -C password -U u0_aXX -G u0_aXX

The above command will run the Dropbear server with password authentication enabled for the user 'user' with password 'password' and will attempt to run as u0_aXX and in that group. More information can be found by issuing:

./dropbear --help

Credits

Big thanks to mkj who has been maintaining Dropbear:
https://github.com/mkj/dropbear

Thanks to NHellfire who's work made the process of getting 2018.76 up and running much easier:
https://github.com/NHellFire/dropbear-android

Thanks to jmfoy for the config.sub and config.guess files:
https://github.com/jfmoy/android-dropbear

Another thank you to the various other repositories out there whose various approches helped lead to this completed project.

dropbear-android's People

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dropbear-android's Issues

Failed to open any /dev/pty?? devices

Hi
I have problem from subject. I'm trying to run it (on android box with 4.2.2 android version, rooted of course ;) ) as follows:
dropbear -d path_to_dss_key -r p path_to_rsa_key -r path_to_ecdsa_key -p 22 -P path_to_pid -R -N user -C password -U root -G root -A -F

Error log:
...
Failed to open any /dev/pty?? devices
No pty was allocated, couldn't execute
....

Compilation doesn't start with android-ndk-r18b arm64

Download Android NDK r18b.
Create stand-alone toolchain. For example, ~/android-ndk-r18b/build/tools/make_standalone_toolchain.py --arch arm64 -v --install-dir ~/android-toolchain64.
export TOOLCHAIN=~/android-toolchain64
./build-dropbear-android.sh. The build script silently exits after Generating required files....

Upon closer look, modifying variables in build-dropbear-android.sh finished the build.

HOST=aarch64-linux-android
COMPILER=${TOOLCHAIN}/bin/aarch64-linux-android-gcc
STRIP=${TOOLCHAIN}/bin/aarch64-linux-android-strip

Compilation fails with android-ndk-r17b

Here's the error log:

/home/max/Development/Linux/toolchain-arm/bin/arm-linux-androideabi-gcc --sysroot=/home/max/Development/Linux/toolchain-arm/sysroot -Wl,-pie -Wl,-z,now -Wl,-z,relro -o dropbear dbutil.o buffer.o dbhelpers.o dss.o bignum.o signkey.o rsa.o dbrandom.o queue.o atomicio.o compat.o fake-rfc2553.o ltc_prng.o ecc.o ecdsa.o crypto_desc.o gensignkey.o gendss.o genrsa.o common-session.o packet.o common-algo.o common-kex.o common-channel.o common-chansession.o termcodes.o loginrec.o tcp-accept.o listener.o process-packet.o dh_groups.o common-runopts.o circbuffer.o curve25519-donna.o list.o netio.o svr-kex.o svr-auth.o sshpty.o svr-authpasswd.o svr-authpubkey.o svr-authpubkeyoptions.o svr-session.o svr-service.o svr-chansession.o svr-runopts.o svr-agentfwd.o svr-main.o svr-x11fwd.o svr-tcpfwd.o svr-authpam.o libtomcrypt/libtomcrypt.a libtommath/libtommath.a  
dbutil.c:139: error: undefined reference to 'stderr'
dbutil.c:361: error: undefined reference to 'signal'
dbutil.c:280: error: undefined reference to 'signal'
dbrandom.c:92: error: undefined reference to '__FD_SET_chk'
/home/max/Development/Linux/toolchain-arm/sysroot/usr/include/bits/fortify/unistd.h:406: error: undefined reference to '__read_chk'
/home/max/Development/Linux/toolchain-arm/sysroot/usr/include/bits/fortify/string.h:391: error: undefined reference to '__strlen_chk'
/home/max/Development/Linux/toolchain-arm/sysroot/usr/include/bits/fortify/string.h:391: error: undefined reference to '__strlen_chk'
gendss.c:66: error: undefined reference to 'stderr'
genrsa.c:133: error: undefined reference to 'stderr'
genrsa.c:91: error: undefined reference to 'stderr'
common-session.c:157: error: undefined reference to '__FD_SET_chk'
common-session.c:174: error: undefined reference to '__FD_SET_chk'
common-session.c:180: error: undefined reference to '__FD_SET_chk'
common-session.c:206: error: undefined reference to '__FD_ISSET_chk'
common-session.c:218: error: undefined reference to '__FD_ISSET_chk'
common-session.c:414: error: undefined reference to '__FD_ISSET_chk'
common-channel.c:219: error: undefined reference to '__FD_ISSET_chk'
/home/max/Development/Linux/toolchain-arm/sysroot/usr/include/bits/fortify/string.h:391: error: undefined reference to '__strlen_chk'
sshpty.c:219: error: undefined reference to 'tcgetattr'
sshpty.c:228: error: undefined reference to 'tcsetattr'
sshpty.c:274: error: undefined reference to 'signal'
svr-chansession.c:159: error: undefined reference to 'sigemptyset'
svr-chansession.c:1047: error: undefined reference to 'sigemptyset'
svr-chansession.c:817: error: undefined reference to 'signal'
svr-chansession.c:481: error: undefined reference to 'tcgetattr'
svr-chansession.c:553: error: undefined reference to 'tcsetattr'
svr-main.c:394: error: undefined reference to 'sigemptyset'
svr-main.c:352: error: undefined reference to 'sigemptyset'
bn_mp_rand.c:36: error: undefined reference to 'rand'
bn_mp_rand.c:36: error: undefined reference to 'rand'
bn_mp_rand.c:36: error: undefined reference to 'rand'
bn_mp_rand.c:36: error: undefined reference to 'rand'
collect2: error: ld returned 1 exit status
make: *** [Makefile:177: dropbear] Fehler 1

Not really sure what I could be doing wrong..

ubiquiti / dropbear-android Goto Github PK

dropbear-android's Introduction

Android Dropbear

Building Dropbear for Android

Customizations

Basic usage

Credits

dropbear-android's People

Contributors

Stargazers

Watchers

Forkers

dropbear-android's Issues

Failed to open any /dev/pty?? devices

Compilation doesn't start with android-ndk-r18b arm64

Compilation fails with android-ndk-r17b

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