Home / ubuntu / Questions

Questions[chroot](ubuntu)

Martin Hope
user5950
Asked: 2014-05-20 07:43:56 +0800 CST
  • 18

I try to repair an broken Ubunu 14.04 with chroot. What I did, is to boot Ubuntu from USB mounted the original system that has to be repaired and changed to this system with chroot:

sudo mount /dev/sdXY /mnt 
sudo mount -o bind /dev /mnt/dev 
sudo mount -o bind /sys /mnt/sys 
sudo mount -t proc /proc /mnt/proc 
sudo cp /proc/mounts /mnt/etc/mtab 
sudo chroot /mnt /bin/bash

That worked fine, but in chroot environment I don't have access to the internet, so apt isn't able to resolve hostnames. What am I supposed to do? 

ping www.askubuntu.com

does not work either.

chroot
Martin Hope
Oli
Asked: 2012-05-10 05:43:59 +0800 CST
  • 140

I want to give a client access to my server, but I want to limit those users to their home directories. I will bind-mount in any files I want them to be able to see.

I've created a user called bob and added him to a new group called sftponly. They have a home directory at /home/bob. I've changed their shell to /bin/false to stop SSH logins. Here is their /etc/passwd line:

bob:x:1001:1002::/home/bob:/bin/false

I've also changed the /etc/ssh/sshd_config to include the following:

Match Group sftponly
        ChrootDirectory /home/%u
        ForceCommand internal-sftp
        AllowTcpForwarding no

When I try to log in as them, here's what I see 

$ sftp bob@server
bob@server's password: 
Write failed: Broken pipe
Couldn't read packet: Connection reset by peer

If I comment out the ChrootDirectory line I can SFTP in but then they have free rein over the server. I have found that ChrootDirectory /home works, but it still gives them access to any home directory. I have explicitly tried ChrootDirectory /home/bob but that doesn't work either.

What am I doing wrong? How can I limit bob to /home/bob/?

----EDIT-----

Okay so I just had a look at /var/log/auth.log and saw this:

May  9 14:45:48 nj sshd[5074]: pam_unix(sshd:session): session opened for user bob by (uid=0)
May  9 14:45:48 nj sshd[5091]: fatal: bad ownership or modes for chroot directory component "/home/bob/"
May  9 14:45:48 nj sshd[5074]: pam_unix(sshd:session): session closed for user bob

I'm not entirely sure what's going on there, but it suggests something is wrong with the user directory. Here is the ls -h /home output:

drwxr-xr-x 26 oli      oli      4096 2012-01-19 17:19 oli
drwxr-xr-x  3 bob      bob      4096 2012-05-09 14:11 bob
ssh sftp chroot
Martin Hope
hookenz
Asked: 2012-03-08 10:50:45 +0800 CST
  • 11

I've been building a live Ubuntu server (10.04 LTS) to run off a thumb drive and it's nearly there.

However, I've gotten stuck at one step.

I need to run update-grub but it's complaining about:

/usr/sbin/grub-probe: error: cannot find a device for / (is /dev mounted?).

My fstab file contains:

# filesystem   mount point     type    options                 dump    pass
UUID=76d2077e-9726-4f95-abab-323cb426b099       /               ext2    defaults                0       0
proc            /proc           proc    nodev,noexec,nosuid 0       0
sys             /sys            sysfs   defaults                0       0
command-line grub2 chroot
Martin Hope
Grand Oxymore
Asked: 2010-11-22 03:29:41 +0800 CST
  • 26

I was following the instructions of this tutorial HOWTO: Purge and Reinstall Grub 2 from the Live CD, when I encountered an error at step 1, as I launched the command

sudo chroot /mnt/temp

The error was the following:

chroot: failed to run command `/bin/bash': Exec format error

Where does that come from? How do I get through?

bash chroot