Dropbear ssh tunneling segfault

[Hayk Beglaryan]

Dear Matt,

Thanks for fast reply. 
[1] Yes I run dropbear from adb shell and it’s works correctly. My steps are followings: 
	$ adb connect [device ip]
	$ adb shell
	# su
	# dropbear -E -R

[2] Please find requested logfile1.txt attached.

[3] Running "ssh -i ssh_rsa_key root at localhost -p 56048 df” doesn’t work at all.

Regard,
Hayk 

-------------- next part --------------
An embedded and charset-unspecified text was scrubbed...
Name: logfile1.txt
Url: http://lists.ucc.gu.uwa.edu.au/pipermail/dropbear/attachments/20180321/aeb9187b/attachment.txt 
-------------- next part --------------



> On Mar 21, 2018, at 5:02 PM, Matt Johnston <matt at ucc.asn.au> wrote:
> 
> Hi Hayk,
> 
> I wonder if a service running from init.rc has different restrictions on what a process is allowed to do. Maybe a syscall that usually succeeds is blocked by the system, and Dropbear doesn't handle it well. When you run it manually you are running it under adb?
> 
> Can you make your myScript launcher redirect dropbear output to a file
> 
> dropbear -E -R > /data/logfile1.txt 2>&1
> 
> and see if anything gets logged there?
> 
> If you run 
> 
> ssh -i ssh_rsa_key root at localhost -p 50216 df
> 
> instead does it work? That won't try to allocate a terminal to run commands.
> 
> Cheers,
> Matt
> 
>> On Wed 21/3/2018, at 2:48 pm, Hayk Beglaryan <hayk.beglaryan7 at gmail.com> wrote:
>> 
>> Hello,
>> 
>> I'm an android developer and we are trying to make a ssh tunneling between Android device and Linux Host. I'm using dropbear for this solution.
>> 
>> Here is my steps:
>> 
>> 1) I'm connecting to my host via dbclient with 0 port
>> 
>>   dbclient -i "$RSA_KEY" -f -N -R 0:localhost:22 "$HOST" -y &> /sdcard/out
>> 
>> 2) Then I'm running dropbear 
>> 
>>   dropbear -E -R
>> 
>> 3) And now I'm able to connect to device via ssh from my host using public key and port in /sdcard/out 
>> 
>>   ssh -i ssh_rsa_key root at localhost -p 50216
>> 
>> Here is it, and it's works perfectly.
>> For my solution I need to make tunneling automatically. 
>> 
>> I have created bash script under /system/bin/ (build android image with script in it). Added corresponding service in init.rc to run my script automatically. 
>> 
>>    service myScript /system/bin/myScript
>>         class core
>>         user root
>>         group root
>>         disabled
>> 
>> The script actually runs by system every 5 sec. but when I'm trying to connect to device I receive following error message:
>> 
>>   "Aiee, segfault! You should probably report this as a bug to the developer"
>> 
>> The strangest thing is that when I'm running my script manually it works fine but when system runs the **same** script I receive upper described error message.
>> 
>> "dmesg", "logcat", even "ssh ... -vvv" don't give any error message.
>> 
>> I think problem is in "dropbear" itself, because when system runs "dbclient" and then I run "dropbear -E -R" manually , tunneling works correctly. 
>> 
>> This is my output of "ssh ... -v"
>> 
>> 
>>     OpenSSH_7.6p1, LibreSSL 2.6.2
>>     debug1: Reading configuration data /etc/ssh/ssh_config
>>     debug1: /etc/ssh/ssh_config line 48: Applying options for *
>>     debug1: Connecting to localhost port 50643.
>>     debug1: Connection established.
>>     debug1: key_load_public: No such file or directory
>>     debug1: identity file ssh_rsa_key_to_box type -1
>>     debug1: key_load_public: No such file or directory
>>     debug1: identity file ssh_rsa_key_to_box-cert type -1
>>     debug1: Local version string SSH-2.0-OpenSSH_7.6
>>     debug1: Remote protocol version 2.0, remote software version dropbear_2017.75
>>     debug1: no match: dropbear_2017.75
>>     debug1: Authenticating to localhost:50643 as 'root'
>>     debug1: SSH2_MSG_KEXINIT sent
>>     debug1: SSH2_MSG_KEXINIT received
>>     debug1: kex: algorithm: curve25519-sha256 at libssh.org
>>     debug1: kex: host key algorithm: ssh-rsa
>>     debug1: kex: server->client cipher: aes128-ctr MAC: hmac-sha2-256 compression: none
>>     debug1: kex: client->server cipher: aes128-ctr MAC: hmac-sha2-256 compression: none
>>     debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
>>     debug1: Server host key: ssh-rsa SHA256:M1PmvueMNfm4q47UlzVWZMdB6YzxyYBy4I5hden9ctU
>>     debug1: Host '[localhost]:50643' is known and matches the RSA host key.
>>     debug1: Found key in /Users/haykbeglaryan/.ssh/known_hosts:23
>>     debug1: rekey after 4294967296 blocks
>>     debug1: SSH2_MSG_NEWKEYS sent
>>     debug1: expecting SSH2_MSG_NEWKEYS
>>     debug1: SSH2_MSG_NEWKEYS received
>>     debug1: rekey after 4294967296 blocks
>>     debug1: SSH2_MSG_SERVICE_ACCEPT received
>>     debug1: Authentications that can continue: publickey
>>     debug1: Next authentication method: publickey
>>     debug1: Trying private key: ssh_rsa_key_to_box
>>     debug1: Authentication succeeded (publickey).
>>     Authenticated to localhost ([::1]:50643).
>>     debug1: channel 0: new [client-session]
>>     debug1: Entering interactive session.
>>     debug1: pledge: network
>>     debug1: Sending environment.
>>     debug1: Sending env LC_CTYPE = UTF-8
>>     debug1: client_input_channel_req: channel 0 rtype exit-status reply 0
>>     Aiee, segfault! You should probably report this as a bug to the developer
>>     debug1: channel 0: free: client-session, nchannels 1
>>     debug1: fd 1 clearing O_NONBLOCK
>>     Connection to localhost closed.
>>     Transferred: sent 2640, received 1816 bytes, in 0.0 seconds
>>     Bytes per second: sent 312354.4, received 214861.9
>>     debug1: Exit status 1
>> 
>> 
>> Best regards:
>> — 
>> Hayk Beglaryan, Software developer
>> Mobile: +374 (41) 550 309
>> 
>