Login attempt for nonexistent user

[Laurent Bourdel]

Hi Matt,

Yes you are right, with strace i see missing files :
03   open("/usr/lib/libnss_compat.so.2", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
103   stat64("/usr/lib", {st_mode=S_IFDIR|0775, st_size=4096, ...}) = 0
103   open("/lib/libnss_files.so.2", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
103   open("/usr/lib/libnss_files.so.2", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)

I build glibc-2.22 and install lib in my UDOO's rootfs

After that, dropbear is working nice :
118   open("/usr/lib/libnss_compat.so.2", O_RDONLY|O_CLOEXEC) = 7
118   read(7, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0(\0\1\0\0\0x\r\0\0004\0\0\0T\257\1\0\2\4\0\0054\0"..., 512) = 512
118   fstat64(7, {st_mode=S_IFREG|0755, st_size=111940, ...}) = 0
118   mmap2(NULL, 86620, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 7, 0) = 0x76d60000
118   mprotect(0x76d64000, 65536, PROT_NONE) = 0
118   mmap2(0x76d74000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 7, 0x4000) = 0x76d74000
118   close(7)                          = 0
Thanks a lot Matt

I just have one question about dropbear_dss_host_key & dropbear_rsa_host_key
I don't why we need to generate these keys ?

We normally only need public key from client in authorized_key file ?

Have a nice week
Laurent




Le mercredi 31 octobre 2018 à 14:35:44 UTC+1, Matt Johnston <matt at ucc.asn.au> a écrit : 





Hi Laurent,

My best guess is that it was built on lubuntu which uses glibc, but the Udoo board doesn't have the required /lib/somewhere/libnss*.so libraries - those get chosen at runtime based on /etc/nsswitch.conf. Building using a uclibc cross compiler would avoid that - how did you build it? Also which distribution does Udoo use?

If you can install strace on the Udoo board you can see what files are being tried with
strace -f -F -o logfile -s 300 dropbear -vFE

Cheers,
Matt


> On Tue 30/10/2018, at 5:28 pm, Laurent Bourdel <lbourdel at yahoo.fr> wrote:
> 
> 
> 
> 
> with correct subject :
> 
> Hi,I fail to login with ssh client to dropboxI use Udoo ARM board with busybox to install ssh serverI cross compiled dropbear under VirtualBox lubuntu and install binary to board ( /bin & /sbin)I generate RSA key (ssh-keygen -t rsa ) under lubuntu and copied  content to /home/root/.ssh/authorized_keys on Udoo boardI run on Udoo board : dropbear -vFEOn VM lubuntu : ssh  -vvv root at 192.168.0.2I add trace on dropbear sources and found problem come with function getpwnam to read /etc/password with errno=0;pw = getpwnam(username);dropbear_log(LOG_WARNING,"LBR %s %d %s",__FILE__ ,__LINE__, strerror(errno));if (!pw) {return;}[157] Jan 01 01:06:50 LBR common-session.c 595 No such file or directory