[Samba] Managing Kerberos tickets via winbind on a laptop

Jon Gerdes gerdesj at blueloop.net
Fri Oct 13 23:21:56 UTC 2017

Dear all

I'm not too sure where to start here - possibly a feature request. I am getting great results with using Winbind to manage Kerberos tickets for Linux workstations "joined" to an AD.

Fixed machines work beautifully - I have Raspberry Pis and PCs (running Arch and Gentoo) and servers running Ubuntu LTS , all doing Kerberos against AD KDCs with local logins via AD and local unix users as required, RDP inbound and outbound, SSH in and out, email (Evolution) to Exchange, Firefox and Chrome/Chromium doing their stuff with Squid, Apache and nginx and even IIS (shock, horror). Kerberos just works.

Now, I'm moving out a bit and looking at laptops, where the network comes and goes and could suddenly be on the end of a VPN, and the system can go to sleep for a long time, often all at once. To be honest it still works pretty well - but sometimes needs a bit of patience and a few prods.

When a (domain joined) laptop comes out of sleep I need it need to:

* Wake up hardware, basic OS
* Reconnect network (if known wifi, then easy - reconnect, if not then that's another story and sort out VPN if applicable)
* Fix up time
* Realistically determine whether KDC is available or not - fall back to cached login = yes - /etc/security/pam_winbind.conf and winbind offline logon  = yes in smb.conf (this is a tricky one)
---- Short time out, say 5-10s or configurable, if needed to get the above to work -----
* Refresh Kerberos tickets as needed, if KDC available
< ------ lock screen here
* User logs in, running apps work and job's a good 'un

What actually happens:
* Wake up hardware, basic OS
*** stuff, user speed dependent ***
<----- lock screen here
*** Some times Evo connects first time and so do web browsers etc and all is lovely
*** Wait a while and the Kerb tickets are refreshed and everything works
*** Sometimes I lose patience and restart winbind or start making pointed use of "net ads info, as root" and the Kerberos dependent apps suddenly start working

I've read all the docs I can on winbind (including man pages) and I can't see an easy (progammatic, say via KDE events) way to kick it into refreshing Kerberos tickets on demand. It is clearly able to notice when the network is available or not because it will do the job eventually.


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