General Notes

Windows

Expand a windows partition after expanding the virtual disk (Ex. sendys)

Note: Windows Server 2008, Windows Server 2008 R2, Windows Vista, Windows 7, Windows 8 and Windows Server 2012, Windows 8.1, Windows 10 and Windows Server 2012 R2 can expand the volumes from the Disk Management in Computer Management. Right-click on Volume and click Extend Volume. For more information, see Microsoft's documentation. Instead of rebooting the guest operating system, in Computer Management, right-click Disk Management and click Rescan Disks.

OSX

Reset password on OSX

Turn off your Mac (choose Apple > Shut Down).
Press the power button while holding down Command-R. The Mac will boot into Recovery mode. When you see the load bar appear you can let go of the keys. It may take a few minutes to load.
Select Disk Utility and press Continue.
Choose Utilities > Terminal.
Enter resetpassword (all one word, lowercase letters) and press Return
Select the volume containing the account (normally this will be your Main hard drive).
Choose the account to change with Select the User Account.
Enter a new password and re-enter it into the password fields.
Enter a new password hint related to the password.
Click Save.
A warning will appear that the password has changed, but not the Keychain Password. Click OK.
Click Apple > Restart

FreeNAS

Mounting NFS Volumes (ex. external usb disks) on FreeNAS

mkdir /mnt/usb
kldload fuse
ntfs-3g /dev/da0s1 /mnt/usb/

Zentyal

Showing Password Policy Settings

$ sudo samba-tool domain passwordsettings show
Password informations for domain 'DC=arditi,DC=pt'

Password complexity: off
Store plaintext passwords: off
Password history length: 24
Minimum password length: 0
Minimum password age (days): 0
Maximum password age (days): 365
Account lockout duration (mins): 30
Account lockout threshold (attempts): 0
Reset account lockout after (mins): 30

Changing Password Policy Settings

Set password complexity

 $ sudo samba-tool domain passwordsettings set --complexity=on

Set password minimum length

 $ sudo samba-tool domain passwordsettings set --min-pwd-length=6

Disable Password Expiration

 $ sudo samba-tool user setexpiry USER --noexpiry
 Expiry for user USER disabled.

Re-enable Password Expiration

see: https://www.samba.org/samba/docs/current/man-html/pdbedit.8.html

$ sudo /usr/bin/pdbedit -u caguiar -r -c [-X]
ldb_wrap open of idmap.ldb
Unix username:        caguiar
NT username:          
Account Flags:        [U          ]
User SID:             S-1-5-21-1969551146-1524703261-742246316-1105
Primary Group SID:    S-1-5-21-1969551146-1524703261-742246316-513
Full Name:            Clemente Aguiar
Home Directory:       \\hera.ARDITI.PT\caguiar
HomeDir Drive:        H:
Logon Script:         
Profile Path:         
Domain:               
Account desc:         
Workstations:         
Munged dial:          
Logon time:           Thu, 09 Apr 2020 16:44:52 WEST
Logoff time:          0
Kickoff time:         0
Password last set:    Sun, 19 Apr 2020 15:09:32 WEST
Password can change:  Sun, 19 Apr 2020 15:09:32 WEST
Password must change: never
Last bad password   : 0
Bad password count  : 0
Logon hours         : FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF

Linux

Disable Linux Account

The correct way according to usermod(8) is:

usermod --lock --expiredate 1970-01-02 <username>

(Actually, the argument to --expiredate can be any date before the current date in the format YYYY-MM-DD.)

Explanation:

--lock locks the user's password. However, login by other methods (e.g. public key) is still possible.
--expiredate YYYY-MM-DD disables the account at the specified date. According to man shadow 5 1970-01-01 is an ambiguous value and shall not be used.

Re-enable Linux Account

usermod --unlock --expiredate  <username>

Change the space reserved for root on an ext2, ext3 or ext4 filesystem

Reference: http://www.microhowto.info/howto/reduce_the_space_reserved_for_root_on_an_ext2_ext3_or_ext4_filesystem.html

The reservation can be changed using the -m option of the tune2fs command:

tune2fs -m X /dev/sda1

The X number is the required percentage (without a percentage sign). If successful, tune2fs should report the new reservation with a message of the form:

tune2fs 1.41.12 (17-May-2010)
Setting reserved blocks percentage to X% (y blocks)

Ubuntu: How do I find the package that provides a file?

Reference: https://askubuntu.com/questions/481/how-do-i-find-the-package-that-provides-a-file

You can use dpkg command to find out which installed package owns a file:

From man dpkg:

-S, --search filename-search-pattern...
                 Search for a filename from installed packages.

Example:

$ dpkg -S /bin/ls
coreutils: /bin/ls

You can either search with a full path or with just the filename.

Ubuntu Servers: adjust swappiness

Reference: http://ubuntuguide.net/optimize-the-usage-of-swap-to-speed-up-response-for-ubuntu

First, check the value of swappiness:

cat /proc/sys/vm/swappiness

Set the swappiness value to 10 (production server):

sudo sysctl vm.swappiness=10

To permanently change this value, create a file 20-swappiness.conf in /etc/sysctl.d with the following line:

vm.swappiness=10

Certbot

Add additional domain to an existing certificate

sudo certbot certonly --cert-name oomvisor.arditi.pt -d oomvisor.arditi.pt,geoportal.arditi.pt