Service Desk Knowledgebase: Linux: Difference between revisions

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'''a''' for INSERT mode and type/paste in the ''password'' then '''[ESC]''' and  ''':wq''' and press '''[Enter]'''
'''a''' for INSERT mode and type/paste in the ''password'' then '''[ESC]''' and  ''':wq''' and press '''[Enter]'''


11. '''sudo -u $<font color="red">$CRSid</font> vi .ipmi-pw'''
11. '''sudo -u $<font color="red">$CRSid</font> vi .ipmi-pw'''<br />
'''a''' for INSERT mode and type/paste in the ''password'' then '''[ESC]''' and  ''':wq''' and press '''[Enter]'''
'''a''' for INSERT mode and type/paste in the ''password'' then '''[ESC]''' and  ''':wq''' and press '''[Enter]'''


Revision as of 14:17, 23 February 2015


This is the Linux content page of the CL Wiki Service Desk Knowledgebase. Its purpose is to provide information to the Service Desk team on how to handle problems and requests about this CL service. If you are involved with the provision of this CL service please feel free to add to the knowledge about that it.

If CL staff need to tell the Service Desk team about problems with this service please email
sys-admin-aside@cl.cam.ac.uk.

Return to the Service Desk Knowledgebase SERVICE PORTFOLIO

Key Service Description & URLs

CL Customer Documentation

Further CL Sys-Admin Resources

Underpinning Services

  • ??? - Any supporting or underpinning services

Customer-base for this Service

  • Linux boxes are available to all staff and post-graduates, and well as some on the Part III Under-graduates.

Costs

  • Hardware is charged for if you are a Research Assistant or a University Teaching Officer, but free to Post-graduates.
  • Support is free.

SLA

  • ??? - Timeframes or service level agreement for fulfilling the service

Service Desk Call Handling Procedure

  • RT tickets can be escalated to the unix-admin by changing the Queue to unix-admin with the Owner set to Nobody & Status set to new. Tell the requestor:
    I am passing this request over to our Unix Admin team who, I'm sure, will be in contact shortly.

Contacts

Primary

Other

Availability

  • Monday: 09:00-17:00
  • Tuesday: 09:00-17:00
  • Wednesday: 09:00-17:00
  • Thursday: 09:00-17:00
  • Friday: 09:00-17:00
  • Saturday: Closed
  • Sunday: Closed

Hints, Tips & Known Issues

Removing a broken install

Vince Woodley (17 Feb 2015)

ssh to the machine in question then...

1) Find the process responsible for the lock with sudo lsof /var/lib/dpkg/lock

2) Check for running dpkg processes with something like ps -ef | grep dpkg

3) Ask the requestor if they'd like you to kill it:
I suspect I could do that by killing the rogue process -- shall I have a go?

4) Kill any dpkg processes shown above with sudo kill 1234 etc...
If they refuse to die try sudo kill -HUG 1234

5) Check each is dead with the same command again sudo kill 1234 (hopefully there will be no such process)

6) Find the exact name of the dropbox package with dpkg -l \*dropb\* (or similar)

7) Remove it with cl-asuser apt-get remove nautilus-dropbox
(or similar) If that fails with:-
"dpkg was interrupted, you must manually run 'sudo dpkg --configure -a' to correct" then cd /var/lib/dpkg/updates and delete all the files there with rm *

8) Do an update of the system with cl-update-system

9) Check the output to make sure that everything's okay repeating cl-update-system if necessary

Clock slew problem

Graham Titmus (3 Feb 2015)

First check if this is a physical machine or a VM. If a physical machine login to it. If a Xen VM then login to it and check if it is tied to the dom0 clock. 

cat /proc/sys/xen/independent_wallclock

If that returns an error then proceed as for a standalone machine. If it returns 0 then you need to find the dom0 which hosts the VM, to find that do 

cl-onserver --xe cl-vm-status all hid | grep <<machine_name>>

When logged in to the appropriate machine (using ssh or in the case of Xen you could also connect via the Xen Centre guy) first check if it is working correctly 

/usr/sbin/ntpdc -p

which should not look like this 

 remote local st poll reach delay offset disp
 =======================================================================
 *LOCAL(0) 127.0.0.1 10 64 377 0.00000 0.000000 0.03046

but have multiple lines each to a remote ntp server.

If it does look like above then restart the ntpd service 

 cl-asuser service ntpd restart

and check the output again which should now look like 

remote local st poll reach delay offset disp
=======================================================================
=morgul.deadset. 128.232.26.100 16 64 0 0.00000 0.000000 4.00000
=time-b.as43289. 128.232.26.100 16 64 0 0.00000 0.000000 4.00000
=LOCAL(0) 127.0.0.1 10 64 1 0.00000 0.000000 2.81735
=ntp.katho.be 128.232.26.100 16 64 0 0.00000 0.000000 4.00000
=server.netkolik 128.232.26.100 16 64 0 0.00000 0.000000 4.00000
=ntp1d.cl.cam.ac 128.232.26.100 2 64 1 0.00070 0.002260 2.81735
=ntp1c.cl.cam.ac 128.232.26.100 2 64 1 0.00165 0.002201 2.81743
=ntp1b.cl.cam.ac 128.232.26.100 2 64 1 0.00121 0.003449 2.81743
=ntp1a.cl.cam.ac 128.232.26.100 2 64 1 0.00058 0.002520 2.81735

Linux user can't login using graphical interface

Graham Titmus (13 Jan 2015)

Symptoms: Linux user can't login using graphical interface, they enter username and password and get a blank screen then back to login

A common cause of this is a failure to access the home directory stored on the File Server (AKA Elmer or Filer), X (the window manager) needs to write a file there when it starts the user session. To diagnose if this is the problem do the following:-

  1. Remote login to the machine using ssh -K hostname@cl.cam.ac.uk from a CL machine - check if your home directory is present (ls -al ~). If is is look to see if the users home directory is present (ls -al ~crsid).
  2. If the home directory is missing then try to restart the auto mounter (cl-asuser service autofs restart).
  3. Look at the mounted filesystems (grep ldap /proc/mounts - will show which systems have been auto mounted using data form the LDAP).


An alternative is to ask the user to check if it is the machine failing to log them in or a problem with X by getting them to try on the text console (Select with Ctrl-Alt-F2). If they can login there but have no home then it is probably a problem with the filesystem. If they cannot login at all then it is an authentication problem. They should then try from another machine that is known to work to check their login works.

Adding privileged users

Linux PCs Assigned to Users:
Machines are setup with a single 'assigned user' having both cl-asuser access (due to owning the file /etc/user-config/bundles) and sudo access (due to being in a suitable group which has sudo rights). If the assigned user has not been setup (because a machine has been moved to a new user or was not done when the machine was installed) login and first run cl-asuser cl-hostid-fix --user $CRSid which will show you what it thinks needs to be done and (if it looks okay) then run cl-asuser cl-hostid-fix --user $CRSid -a to actually do it. Then [Edit] & [Update] the machine names' entry(s) in the inventory and set the User: $CRSid and a Comment like RT#12345 User=$CRSid.

Group Servers & PCs with multiple admins:
For group servers which may want multiple admins, they can use being in the sudo group to grant privileges to other users. Liaise with the machine owner to check what is wanted. To actually do it:

First ssh -K $hostname (if it's not turned on try cl-boot-mc on any of the slogin machines, or Wake-on-Lan (WoL) - wait 3-4 minutes for it to appear online) and then...

cl-asuser access: (if ACLs are enabled) is setup using sudo setfacl -m u:$CRSid:rw /etc/user-config/bundles where $CRSid should be replaced by the CRSid of the person who is to be granted privilege. cl-asuser privileges should then be available immediately.

sudo access: is setup by using an editor to add them to the relevant group (e.g. sudo or root) in the file /etc/group. To do this ssh -K $hostname and then:

  1. sudo vi /etc/group
  2. [sudo] password for abc123: enter your CL password
  3. Add the user's CRSid to the line like sudo:x:27:localadmin,sg692 by scrolling down to it with the arrow-keys and using [Shift]+A to enter --- INSERT --- mode and typing in ,$CRSid
  4. [ESC] out of insert mode
  5. Write and quit with :wg and [Enter]

(Note that sudo privileges will only take effect in new sessions.)

If there are sudo problems use groups $CRSid to check which groups the user is in, and sudo -l -U $CRSid to check the status. Check /etc/sudoers using sudo view sudoers and /etc/sudoers.d/* to check which groups give ALL access.

"It gave an error" or "It failed to work"

Piete Brooks (20 Feb 2015)

If someone says something like "It gave an error" or "It failed to work" on a Linux system please ask the following: 

 Dear ???
 Could you please send us a copy & paste of the command  
 that you ran and the output that it generated?
 Also, would you please run the commands:
 
 groups
 sudo -l
 
 and copy & paste the output of those into the same reply to this email.
 
 Many thanks,
 ???


BMC ACL - when up if present

Based on http://www.wiki.cl.cam.ac.uk/clwiki/SysInfo/MachineSetup?action=diff&rev2=49&rev1=48

Piete Brooks (23 Feb 2015)

1. Make sure Pageant.EXE is running and has your private key - by double clicking on CL.ppk or similar.

2. With it running in the system tray launch PuTTY and go to the CL's ssh-remote-0.cl.cam.ac.uk

3. Type kinit & press [Enter]

4. Enter your CL Password for CRSid@AD.CL.CAM.AC.UK & press [Enter]

5. Use ssh -K toton & press [Enter] to get the toton:~$ prompt

6. cd /home/$CRSid/ and [Enter]

7. sudo -u $CRSid vi .amtuser
a for INSERT mode and type/paste in the CRSid then [ESC] and :wq and press [Enter]

8. sudo -u $$CRSid vi .ipmi-user
a for INSERT mode and type/paste in the CRSid then [ESC] and :wq and press [Enter]

9. Create an 8 character password using at least one:

  • lower case letter
  • UPPER CASE LETTER
  • digit
  • special characters: !@#$%^&*()

10. sudo -u $$CRSid vi .amtpw
a for INSERT mode and type/paste in the password then [ESC] and :wq and press [Enter]

11. sudo -u $$CRSid vi .ipmi-pw
a for INSERT mode and type/paste in the password then [ESC] and :wq and press [Enter]

12. exit and [Enter]

13. From a Lab machine, open a web-browser and to the BMC interface at:

14. Login as admin, delete any previous assigned user, and add the new one.

Categorising Keywords

  • Linux Ubuntu PC Person Computer
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