problem with dropbear [SOLVED, or at least explained]

[Guest kendon]

just noticed something strange. i set up my dropbear to use kendon as username. then i accidently tried to login as root, which worked.

well, so far it seems the username is not checked at all:

kendon@nx:~$ ssh kendon@hero -p 2222

# id

uid=0 gid=0 groups=0

# Connection to hero closed.

kendon@nx:~$ ssh root@hero -p 2222

# id

uid=0 gid=0 groups=0

# Connection to hero closed.

kendon@nx:~$ ssh the_pope@hero -p 2222

# id

uid=0 gid=0 groups=0

# Connection to hero closed.

kendon@nx:~$ ssh god@hero -p 2222

# id

uid=0 gid=0 groups=0

# Connection to hero closed.

kendon@nx:~$ ssh satan@hero -p 2222

# id

uid=0 gid=0 groups=0

# Connection to hero closed.

this is the dropbear command:

dropbear -A -N kendon -U 0 -G 0 -C "$passwd" -R /data/dropbear/authorized_keys -d /data/dropbear/dss_host_key -r /data/dropbear/rsa_host_key -p 2222

any ideas? it's not that bad with a secure password, but i am not sure if i can trust dropbear at all?

Edited January 13, 2010 by kendon

[Guest stevenz]

Presumably the explicit username for -N (supposedly) locks the server to only allow a login with that specific name other than the default?

Try specifying something via the -b switch so you get some visual feedback and see if it's actually paying _any_ attention to what you're telling it.

[Guest kendon]

Presumably the explicit username for -N (supposedly) locks the server to only allow a login with that specific name other than the default?

Try specifying something via the -b switch so you get some visual feedback and see if it's actually paying _any_ attention to what you're telling it.

i checked the log, now i am not sure whether i got the whole user thing for dropbear right. this is my log:

[1758] Jan 13 11:02:47 Not backgrounding

[1761] Jan 13 11:03:49 Child connection from 127.0.0.1:57255

[1761] Jan 13 11:03:51 pubkey auth succeeded for 'kendon' with key md5 xx::yy from 127.0.0.1:57255

[1761] Jan 13 11:04:21 exit after auth (kendon): Exited normally

[1763] Jan 13 11:04:30 Child connection from 127.0.0.1:57256

[1763] Jan 13 11:04:30 pubkey auth succeeded for 'kendon' with key md5 xx::yy from 127.0.0.1:57256

[1763] Jan 13 11:05:04 exit after auth (kendon): Exited normally

first try with kendon, second with root as username. does the N switch specify the username with which i log in or the username that is used on the clientside?

[Guest kendon]

first try with kendon, second with root as username. does the N switch specify the username with which i log in or the username that is used on the clientside?

i guess i was right:

kendon@nx:~$ ssh kendon@localhost -p 2222

# id

uid=0 gid=0 groups=0

# echo $USER

kendon

# Connection to localhost closed.

kendon@nx:~$ ssh root@localhost -p 2222

# id

uid=0 gid=0 groups=0

# echo $USER

kendon

# Connection to localhost closed.

so it isn't a problem at all... still strange, i'd like to set the login username better than setting the clientside username...

thanks for the hint!

Edited January 13, 2010 by kendon