Setup autofs on Ubuntu 18.04

README.md

Mounting CIFS with automount on Ubuntu 18:

1. Install the necessary applications/servers:

   sudo apt install autofs smbclient cifs-utils

2. Configure autofs

create /etc/auto.cifs, with this variant from auto.smb, courtesy howtoforge

#!/bin/bash
# $Id$
# This file must be executable to work! chmod 755!
key="$1"
# Note: create a cred file for each windows/Samba-Server in your network
#       which requires password authentification.  The file should contain
#       exactly two lines:
#          username=user
#          password=*****
#       Please don't use blank spaces to separate the equal sign from the
#       user account name or password.
credfile="/etc/auto.smb.$key"
# Note: Use cifs instead of smbfs:
mountopts="-fstype=cifs,file_mode=0644,dir_mode=0755,uid=user,gid=users"
smbclientopts=""
for P in /bin /sbin /usr/bin /usr/sbin
do
        if [ -x $P/smbclient ]
        then
                SMBCLIENT=$P/smbclient
                break
        fi
done
[ -x $SMBCLIENT ] || exit 1
if [ -e "$credfile" ]
then
        mountopts=$mountopts",credentials=$credfile"
        smbclientopts="-A "$credfile
else
        smbclientopts="-N"
fi
$SMBCLIENT $smbclientopts -gL $key 2>/dev/null \
   | awk -v key="$key" -v opts="$mountopts" -F'|' -- '
        BEGIN   { ORS=""; first=1 }
   /Disk/  { if (first) { print opts; first=0 };
        gsub(/ /, "\\ ", $2);
        sub(/\$/, "\\$", $2);
        print " \\\n\t /" $2, "://" key "/" $2 }
        END     { if (!first) print "\n"; else exit 1 }
        '

Note: you may need to modify the mountopts, for an older ReadyNAS, I used:

mountopts="-fstype=cifs,file_mode=0644,dir_mode=0755,uid=my_user_name,gid=my_user_name,vers=1.0"

Set permissions: chmod 755 /etc/auto.cifs

Create /etc/auto.smb.FILESERVERNAME with something like:

username=user
password=secret

Set permissions: chmod 600 /etc/auto.smb.*

edit /etc/auto.master to add:

/cifs /etc/auto.cifs --timeout=60

3. Fix for No DNS entries

My work network does not have a DNS entry for the file server I want. But I do have an entry in my local /etc/hosts file. I tried adding a name resolve order line to /etc/samba/smb.conf as recommended here, but it didn't work. Looking at the docs, I ended up using dns proxy.

[global]
dns proxy = yes

4. Reload, Restart and enable autofs

sudo systemctl reload autofs.service
sudo systemctl restart autofs.service
sudo systemctl enable autofs.service

5. Verify operation

list the directory with something like: ls /mnt/cifs/server/share

If things don't work, start digging into /var/log/syslog and /var/log/samba/log* (use ls -lrt to find the most recently changed logs).

running automount -f -v instead of with systemctl can be helpful

Running smbclient -L server -d 256 can be helpful. Using smbclient -L server -m SMBx was key for me solving the Mount CIFS Host is down problem.