Please see the following shell interaction for details. To summarize, with a clean boot, gio requests a user name and password instead of using Kerberos credentials. If I kill gvfs first, I can mount, unmount, and remount with Kerberos authentication.
I'm running up-to-date Ubuntu 22.04. I found https://answers.launchpad.net/ubuntu/+source/gvfs/+question/703483 but in this case I'm not specifying the username or domain in the URI. I tried the debugging techniques from https://wiki.gnome.org/Projects/gvfs/debugging but didn't have much luck because the behavior disappears as soon as gvfs restarts. Adding environment variables to /etc/environment didn't give me more debug output. Running gvfsd-smb manually stalls with an error "Error mounting: invalid backend type"
# valid Kerberos ticket is present
caleb@client:~$ klist
Ticket cache: FILE:/tmp/krb5cc_1005_muii0n
Default principal: [email protected]
Valid starting Expires Service principal
08/03/2023 16:48:55 08/04/2023 02:48:55 krbtgt/[email protected]
renew until 08/04/2023 16:48:55
# gvfs running
caleb@client:~$ ps auxw | grep gvfs
gdm 1688 0.0 0.0 240640 7680 ? Ssl 16:48 0:00 /usr/libexec/gvfsd
gdm 1703 0.0 0.0 380888 6336 ? Sl 16:48 0:00 /usr/libexec/gvfsd-fuse /run/user/121/gvfs -f
gdm 1854 0.7 0.0 318148 11904 ? Ssl 16:48 0:00 /usr/libexec/gvfs-udisks2-volume-monitor
gdm 1860 0.0 0.0 315200 7872 ? Ssl 16:48 0:00 /usr/libexec/gvfs-afc-volume-monitor
gdm 1865 0.0 0.0 236580 6528 ? Ssl 16:48 0:00 /usr/libexec/gvfs-mtp-volume-monitor
gdm 1870 0.0 0.0 237540 6720 ? Ssl 16:48 0:00 /usr/libexec/gvfs-gphoto2-volume-monitor
gdm 1874 0.0 0.0 236628 6336 ? Ssl 16:48 0:00 /usr/libexec/gvfs-goa-volume-monitor
caleb 2410 0.0 0.0 240640 7872 ? Ssl 16:48 0:00 /usr/libexec/gvfsd
caleb 2420 0.0 0.0 380888 6528 ? Sl 16:48 0:00 /usr/libexec/gvfsd-fuse /run/user/1005/gvfs -f
caleb 2496 0.1 0.0 327536 11712 ? Ssl 16:48 0:00 /usr/libexec/gvfs-udisks2-volume-monitor
caleb 2543 0.0 0.0 315200 7680 ? Ssl 16:48 0:00 /usr/libexec/gvfs-afc-volume-monitor
caleb 2548 0.0 0.0 236580 6336 ? Ssl 16:48 0:00 /usr/libexec/gvfs-mtp-volume-monitor
caleb 2556 0.0 0.0 237540 6912 ? Ssl 16:48 0:00 /usr/libexec/gvfs-gphoto2-volume-monitor
caleb 2560 0.0 0.0 236628 6336 ? Ssl 16:48 0:00 /usr/libexec/gvfs-goa-volume-monitor
caleb 2741 0.0 0.0 388724 8832 ? Sl 16:48 0:00 /usr/libexec/gvfsd-trash --spawner :1.3 /org/gtk/gvfs/exec_spaw/0
caleb 3134 0.0 0.0 162900 6144 ? Ssl 16:48 0:00 /usr/libexec/gvfsd-metadata
caleb 3181 0.0 0.0 9208 2496 pts/0 S+ 16:49 0:00 grep --color=auto gvfs
# trying to mount a Samba share asks for user + password
caleb@client:~$ gio mount -i 'smb://fileserver.samdom.example.com/users/'
Authentication Required
Enter user and password for share “users” on “fileserver.samdom.example.com”:
User [caleb]: ^C
# cancel, kill gvfs
caleb@client:~$ pkill gvfs
caleb@client:~$ ps auxw | grep gvfs
caleb 3225 0.0 0.0 9076 2304 pts/0 R+ 16:49 0:00 grep --color=auto gvfs
# retry -- now Kerberos auth works fine
caleb@client:~$ gio mount -i 'smb://fileserver.samdom.example.com/users/'
# gvfs has been restarted, but gfvsd-smb is now in the list
caleb@client:~$ ps auxw | grep gvfs
caleb 3229 0.0 0.0 240616 7680 ? Ssl 16:49 0:00 /usr/libexec/gvfsd
caleb 3234 0.0 0.0 380888 6336 ? Sl 16:49 0:00 /usr/libexec/gvfsd-fuse /run/user/1005/gvfs -f
caleb 3236 0.0 0.0 327540 12096 ? Ssl 16:49 0:00 /usr/libexec/gvfs-udisks2-volume-monitor
caleb 3247 0.0 0.0 315196 7680 ? Ssl 16:49 0:00 /usr/libexec/gvfs-afc-volume-monitor
caleb 3252 0.0 0.0 236584 6144 ? Ssl 16:49 0:00 /usr/libexec/gvfs-mtp-volume-monitor
caleb 3256 0.0 0.0 237540 6720 ? Ssl 16:49 0:00 /usr/libexec/gvfs-gphoto2-volume-monitor
caleb 3260 0.0 0.0 236628 6336 ? Ssl 16:49 0:00 /usr/libexec/gvfs-goa-volume-monitor
caleb 3265 0.0 0.0 460588 23808 ? Sl 16:49 0:00 /usr/libexec/gvfsd-smb --spawner :1.106 /org/gtk/gvfs/exec_spaw/0
caleb 3323 0.0 0.0 314888 8448 ? Sl 16:49 0:00 /usr/libexec/gvfsd-trash --spawner :1.106 /org/gtk/gvfs/exec_spaw/1
caleb 3485 0.0 0.0 163004 6336 ? Ssl 16:49 0:00 /usr/libexec/gvfsd-metadata
caleb 3580 0.0 0.0 9076 2496 pts/0 S+ 16:51 0:00 grep --color=auto gvfs
caleb@client:~$
