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Troubleshooting

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Deepanshu Gajbhiye edited this page Jun 21, 2018 · 12 revisions

Troubleshooting

Most problems occur with ltsp setup when we miss some of the steps. Try to properly follow all the steps from whichever guide you are referring to install ltsp server. Here are some common types of problems and how to solve them -

  • Unable to log in with client
  • Local root shell on ltsp client
  • Troubleshooting with a local root shell
  • Blank screen when booted up and constantly reboot
  • Getting low-resolution screen on client

1. Unable to log in with client

This was one of the error that I faced while setting up virtual LTSP server. First, it prompts permanently added the ECDSA host key for IP address to list of kwown host. Later prompts public key denied A solution is to add public key the user to .ssh folder on users home directory. Other solution is changing password authentication no to password authentication yes in /etc/ssh/sshd_config. I have a blog post with all the details - https://medium.com/@gajbhiyedeepanshu/solving-ltsp-client-not-able-to-login-issue-

2. Troubleshooting with a local root shell

This is how a root shell from ltsp client looks like - root_shell It is very helpful for debugging the ltsp server from client. The client boot from the images in /opt/ltsp/images/. One can check ssh key, change root password, etc. There are two possible ways to get one -

  1. add this in /var/lib/tftpboot/ltsp/amd64/lts.conf 
INIT_COMMAND_ROOT_HASH="sed 's!^root:[^:]*:!root:\$6\$p2LdWE6j\$PDd1TUzGvvIkj9SE8wbw1gA/MD66tHHlStqi1.qyv860oK47UnKcafSKqGp7cbgZUPlgyPv6giCVyCSCdJt1b0:!' -i /etc/shadow"

Then you will able to login with username as root and password qwer1234

  1. Other way is also mentioned in ltsp-pnp page ubuntu. That is to add these lines in /var/lib/tftpboot/ltsp/amd64/lts.conf 
SCREEN_02=shell
SCREEN_07=ldm

The official guide suggests on using CTRL+ALT+f2 to get to TTY to log in. But if you are on a VirtualBox that does not work. You have to use RT_CTRL+f2.

3. Blank screen when booted up and costantly reboot

To avoid bug one can put this in lts.conf

INIT_COMMAND_RM_NBD_CHECKUPDATE="rm -rf /usr/share/ldm/rc.d/I01-nbd-checkupdate"

This is caused because some code in nbd creates race condition. One can refer this for more details.

4. Getting low-resolution screen on client

low-resolution This is a common problem when using an old monitor. They tend to use 16-bit colors. This can be fixed by configuring lts.conf. It is located in /var/lib/tftpboot/ltsp/amd64/lts.conf . You can uncomment these line inside. It will force the client to use the resolution you set.

XRANDR_MODE_0=1024x768
XRANDR_RATE_0=85

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