Linux

All about Linux including various configuration procedures, scripts and tips

General

Anything that are related to Linux but does not fit into the category of networking, storage, database or Desktop Environments

General

Batch Image Resize

Keeping Aspect Ratio

mogrify -path [Full path to store the resized images] -resize [width]x[height] -quality [quality] -format [format] *.JPG

No Aspect Ratio

mogrify -path [Full path to store the resized images] -resize [width]x[height]! -quality [quality] -format [format] *.JPG
General

Cheking Printer Ink Level

It can be frustrating sometimes that Linux users aren't able to check the ink levels on our printers like Windows users could, but luckily there are packages that will resolve this problem for major printer manufacturers:

  1. Install libieee1284-devel
  2. Install libinklevel
  3. Install ink
  4. Use command ink -p usb to check
General

Convert PNG to ICO using ImageMagick

convert logo.png -define icon:auto-resize=64,48,32,16 logo.ico
General

How to do Mac/iOS Stuff in Linux

Converting Apple Developer Certificate to .p12 with OpenSSL

  1. Convert the developer certificate file you receive from Apple into a PEM certificate file. Run the following command-line statement from the OpenSSL bin directory: openssl x509 -in developer_identity.cer -inform DER -out developer_identity.pem -outform PEM
  2. If you are using the private key from the keychain on a Mac computer, convert it into a PEM key: openssl pkcs12 -nocerts -in mykey.p12 -out mykey.pem
  3. You can now generate a valid P12 file, based on the key and the PEM version of the iPhone developer certificate: openssl pkcs12 -export -inkey mykey.key -in developer_identity.pem -out iphone_dev.p12
General

Sendmail Sample Usage

mail.txt:

MIME-Version: 1.0 
Content-Type: text/html 
From: newsletter@shopbah.com 
Subject: TESTING 123 hehehe 

<html><head><title>TESTING ONLY BAH</title></head> 
<body> 
<strong>Content line</strong> 1 
<strong>Content line</strong> 2 
<strong>Content line</strong> 3 
</body></html> 

* sendmail address@example.com < mail.txt

General

Windows - Issues

IIS Service Unavailable Error

  1. Search for "run"
  2. In the run dialog, enter "iisreset" and press run

Networking

Linux network troubleshooting and administration

Networking

CentOS 7 - Configuring Cacti

Install Required Dependencies

yum -y install mariadb-server php php-cli php-mysql net-snmp-utils rrdtool php-snmp gcc mariadb-devel net-snmp-devel autoconf automake libtool dos2unix

Enable Required Services for Cacti

chkconfig httpd on
chkconfig mariadb on
chkconfig crond on

Download and Extract Cacti

cd /var/www/html
wget http://www.cacti.net/downloads/cacti-0.8.8c.tar.gz
tar -xzvf cacti-0.8.8c.tar.gz

Setting Up Cacti for Apache

Add Cacti User & Enable Cron Jobs

adduser cacti
echo "*/5 * * * * cacti php /var/www/html/cacti/poller.php &>/dev/null" >> /etc/cron.d/cacti

Fix Cacti Directory Permission

cd /var/www/html/cacti
chown -R cacti.apache rra log
chmod 775 rra log

Set Up Cacti Database

mysql -p cacti < /var/www/html/cacti/cacti.sql
GRANT ALL ON cacti.* TO cactiuser@localhost IDENTIFIED BY 'MyV3ryStr0ngPassword'; 
flush privileges; 
exit
cd /var/www/html/cacti/include/ 
vi config.php (and change $database_* configuration and $url_path)

Open Firewall Ports to HTTP and HTTPS

firewall-cmd --permanent --zone=public --add-service=https 
firewall-cmd --permanent --zone=public --add-service=http 
firewall-cmd --reload

Login to cacti using admin:admin and go to “Console -> System Utilities” and click on “Rebuild Poller Cache” after the first login!

Networking

IPTables - Forwarding Between LAN and WLAN

Add the following to /etc/udev/rules.d/10-network.rules, substitute LAN_MAC_ADDR and WLAN_MAC_ADDR with your Ethernet device and WLAN device MAC addresses for persistent network names:

SUBSYSTEM=="net", ACTION=="add", ATTR{address}=="LAN_MAC_ADDR", NAME="ether0" 
SUBSYSTEM=="net", ACTION=="add", ATTR{address}=="WLAN_MAC_ADDR", NAME="wifi0"

Add the following to /etc/sysctl.d/30-ip_forward.conf:

net.ipv4.ip_forward=1
net.ipv4.conf.default.forwarding=1
net.ipv4.conf.all.forwarding=1 
Add the following to /etc/iptables/iptables.rules: 
*nat 
:PREROUTING ACCEPT [783:65928] 
:INPUT ACCEPT [73:9660] 
:OUTPUT ACCEPT [6180:382480] 
:POSTROUTING ACCEPT [18:1260] 
-A POSTROUTING -o wifi0 -j MASQUERADE 
COMMIT

*filter 
:INPUT ACCEPT [0:0] 
:FORWARD ACCEPT [0:0] 
:OUTPUT ACCEPT [176:192839] 
-A INPUT -i lo -m comment --comment "Inbound from loopback (lo)" -j ACCEPT 
-A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT 
-A INPUT -p icmp -j ACCEPT 
-A INPUT -j NFLOG --nflog-group 1 
-A INPUT -j REJECT --reject-with icmp-host-prohibited 
-A FORWARD -i wifi0 -j ACCEPT 
-A FORWARD -i wifi0 -o ether0 -m comment --comment "ether0 <\- wifi0" -j ACCEPT 
-A FORWARD -i ether0 -o wifi0 -m comment --comment "wifi0 -> ether0" -j ACCEPT 
-A FORWARD -j REJECT --reject-with icmp-host-prohibited 
COMMIT
Networking

Connecting to OpenVPN Using NetworkManager

Install the required packages

sudo apt-get install network-manager network-manager-openvpn network-manager-openvpn-gnome

Creating individual files from client.ovpn file

These files must be kept safe and private at all times

  1. Make a directory called openvpn in your home directory
  2. Copy the client.ovpn file into dir openvpn
  3. Optional: Keep an original copy of the file – call it client.ovpn.orig
  4. Next we will create 4 files under the openvpn directory. Open the client.ovpn file in a text editor
  5. Create a file called ca.crt – copy the text between and from client.ovpn into this file
  6. Create a file called client.crt – copy the text between and from client.ovpn into this file
  7. Create a file called client.key – copy the text between and from client.ovpn into this file
  8. Create a file called ta.key – copy the text between and from client.ovpn into this file
  9. At this point i have a total of 6 files under my openvpn directory

Modify the client.ovpn file

Just before the ## —–BEGIN RSA SIGNATURE—– line add the below lines and save:

ca ca.crt
cert client.crt
key client.key
tls-auth ta.key

Setting up the Network Manager

  1. Click on Ubuntu network icon on the top right
  2. Select VPN Connections -> Configure VPN ( the Network Connections window will open )
  3. Click on the VPN tab and click Import
  4. Select the client.ovpn file we just modified and it should automatically import some things into the next screen
  5. Connection Name will be = client – change this to something meaningful ( i set it to companyVPN )
  6. Gateway must be imported already
  7. Type is : Password with Certificates ( TLS ) – this was also set for me
  8. Provide the username and password for VPN
  9. User certificate will be client.crt
  10. CA certificate will be ca.crt
  11. Private Key will be client.key
  12. Click on Advanced -> TLS Authentication Tab
  13. Key file will be ta.key
  14. Key Direction must be set based on the key direction in your client.ovpn file
  15. Open the client.ovpn file and search for “key-direction” and note the number after that ( mine is key-direction 1 )
  16. Put this number in the Key Direction field in the TLS Authentication Tab
  17. Click save on all windows and close all windows.

Time to test connection

  1. Click on network icon on the top right
  2. Select VPN Connections and you should see your connection there – click it
  3. If successfully connected, you will see a message and then you can verify your IP address with ifconfig
  4. There is a Disconnect VPN under VPN Connection for obvious reasons
Networking

OpenVPN - Firewall Configuration

FirewallD

Use the following commands to open all ports required by OpenVPN:

firewall-cmd --list-services
firewall-cmd --permanent --add-service openvpn
firewall-cmd --permanent --add-masquerade
firewall-cmd --query-masquerade
firewall-cmd --reload

IPTables

My IPTables configuration /etc/iptables/iptables.rules for OpenVPN:

*filter 
:INPUT ACCEPT [0:0] 
:FORWARD ACCEPT [0:0] 
:OUTPUT ACCEPT [32:2712] 
:LOGGING - [0:0] 
-A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT 
-A INPUT -p icmp -m icmp --icmp-type 8 -j REJECT --reject-with icmp-host-prohibited 
-A INPUT -p icmp -m icmp --icmp-type 0 -j REJECT --reject-with icmp-host-prohibited 
-A INPUT -p icmp -j ACCEPT 
-A INPUT -i lo0 -m comment --comment "Allow loopback lo0" -j ACCEPT 
-A INPUT -p tcp -m state --state NEW -m tcp --dport 22 -j ACCEPT 
-A INPUT -p tcp -m state --state NEW -m tcp --dport 80 -j ACCEPT 
-A INPUT -p udp -m udp --dport 1194 -j ACCEPT 
-A INPUT -j LOGGING 
-A INPUT -j REJECT --reject-with icmp-host-prohibited 
-A FORWARD -i tun+ -j ACCEPT 
-A FORWARD -j REJECT --reject-with icmp-host-prohibited 
-A LOGGING -j LOG --log-prefix "DROPPED: " \--log-level 7 
-A LOGGING -j DROP 
COMMIT 
# Completed on Mon Jun 30 06:48:44 2014 
# Generated by iptables-save v1.4.7 on Mon Jun 30 06:48:44 2014 
*nat 
:PREROUTING ACCEPT [0:0] 
:POSTROUTING ACCEPT [2:165] 
:OUTPUT ACCEPT [2:165] 
-A POSTROUTING -s 10.8.0.0/24 -o eth0 -j MASQUERADE 
COMMIT
Networking

RHEL VLAN and Bonding Configuration

Check list:

Configuration

Add the following lines to /etc/modprobe.conf :

alias bond0 bonding

options bonding max_bonds=1

Edit /etc/sysconfig/network-scripts/ifcfg-eth0 it should look something like this:
DEVICE=eth0
USERCTL=no
ONBOOT=yes
MASTER=bond0
SLAVE=yes
BOOTPROTO=none
HWADDR=

Edit /etc/sysconfig/network-scripts/ifcfg-eth1 it should look something like this:
DEVICE=eth1
USERCTL=no
ONBOOT=yes
MASTER=bond0
SLAVE=yes
BOOTPROTO=none
HWADDR=

Now create the Bond0 interface:

NOTE: No IP address will be assigned to the bond0 device.

Create a new file /etc/sysconfig/network-scripts/ifcfg-bond0 it should look like this:

DEVICE=bond0
BOOTPROTO=none
ONBOOT=yes
TYPE=Ethernet

BONDING_OPTS="mode=1 miimon=100"

NOTE: mode could be different, these are the mode options, but if Blade server is using Virtual Connect user should use mode=1.

mode=0 (balance-rr) Round-robin
mode=1 (active-backup) Active-backup
mode=2 (balance-xor) XOR
mode=3 (broadcast) Broadcast
mode=4 (802.3ad) IEEE 802.3ad Dynamic link aggregation
mode=5 (balance-tlb) Adaptive transmit load balancing
mode=6 (balance-alb) Adaptive load balancing

The first four modes are the most commonly used:

VLAN tag setup

This will be a virtual interface with a VLAN tag of 48. User's VLAN set-up is most likely different so just replace 48 with the VLAN tag of user's network. i.e. bond1.50 would be the bonded interface for VLAN 50.

Create a new file /etc/sysconfig/network-scripts/ifcfg-bond0.48 it should look like this:

DEVICE=bond0.48
ONBOOT=yes
TYPE=Ethernet
BOOTPROTO=static
VLAN=yes
NETMASK=255.255.255.0
NETWORK=192.168.48.0
IPADDR=192.168.48.100

Ensure that the default gateway in this configuration is recorded in the /etc/sysconfig/network file otherwise it may not work properly. Once done, it should look something like:

NETWORKING=yes
HOSTNAME=
GATEWAY=192.168.48.1

User has now setup bonding and VLAN tagging. User needs to restart networking to make the changes active.

service network restart

Testing

Verify bonding interface is up and running

ifconfig -a

Verify configuration (RHEL 5 is using sysfs , so check out /sys/class/net/ )

Networking

Setup SFTP to Public Directory (/var/www)

Configuring SSH for SFTP

  1. vim /etc/ssh/sshd_config

  2. Comment the following line:

    1. Subsystem sftp /usr/local/libexec/sftp-server

  3. Add the following lines:

    1. Subsystem sftp internal-sftp
    2. Match Group <sftp group>
    3. ChrootDirectory %h
    4. ForceCommand internal-sftp
    5. X11Forwarding no
    6. AllowTcpForwarding no

  4. Save and close

  5. Reload ssh sudo systemctl restart sshd

Add SFTP User and Set Permission

  1. sudo groupadd <user> -g <sftp group> -s /bin/false -d /var/www/html
  2. sudo passwd <user>
  3. sudo chown root /var/www/html
  4. sudo chmod 755 /var/www/html
  5. sudo mkdir /var/www/html/<dir>
  6. sudo chmod 775 /var/www/html/<dir>
  7. sudo chown apache:apache /var/www/html/<dir>
  8. sudo chmod g+s /var/www/html/<dir>

Selinux

  1. sudo setsebool -P ssh_chroot_rw_homedirs on
  2. sudo setsebool -P httpd_unified 1
  3. sudo setfacl -d -m g:apache:rw /var/www/html/<dir>

References

  1. Spiceworks Article
  2. CentOS Docs
Networking

FirewallD - Opening a Port

Use this command to find your active zone(s):

firewall-cmd --get-active-zones

It will say either public, dmz, or something else. You should only apply to the zones required.

In the case of dmz try:

firewall-cmd --zone=dmz --add-port=<port>/tcp --permanent

Otherwise, substitute dmz for your zone, for example, if your zone is public:

firewall-cmd --zone=public --add-port=<port>/tcp --permanent

Then remember to reload the firewall for changes to take effect.

firewall-cmd --reload
Networking

Using LetsEncrypt for OpenVPN WebSSL

Using letsencrypt for OpenVPN Access Server is nothing more than symlinking the files to letsencrypt keys and certs:

  1. sudo -s
  2. cd /usr/local/openvpn_as/etc/
  3. mv web-ssl web-ssl.bak
  4. mkdir web-ssl
  5. ln -s /etc/letsencrypt/live/<letsencrypt domain dir>/privkey.pem web-ssl/server.key
  6. ln -s /etc/letsencrypt/live/<letsencrypt domain dir>/cert.pem web-ssl/server.crt
  7. ln -s /etc/letsencrypt/live/<letsencrypt domain dir>/fullchain.pem web-ssl/ca.crt
  8. systemctl restart openvpnas
Networking

Monitor Mode on Broadcom-wl Driver

Enable monitor mode:

$ echo 1 > /proc/brcm_monitor0

Enabling monitor mode will create a prism0 network interface. Wireshark and other network tools can use this new prism0 interface.

To disable monitor mode:

$ echo 0 > /proc/brcm_monitor0
Networking

SSH Tunneling

ssh -p <port> <username>@<remote host> -L <local listening port>:<remote's host ip>:<remote's host port> -N

**Note:**
Remote's host and port can be any host and port accessible by the remote host, e.g. to access the router web interface on 192.168.1.1 (remote) use <local listening port>:192.168.1.1:80

Networking

Syncing Files with FTP

I came across a problem when doing migration last time, the server grew too big that I cannot just simply compress the files and move it to another server, it was more than 20GB files. So, I came across an FTP client called LFTP that will synchronize files and folders over FTP. The script below is the script I used to sync the files, let's call it sync.sh:

  1. #!/bin/bash
    HOST='<ftp host>'
    USER='<ftp user>'
    PASS='<password>'
    RCD='<remote directory to sync>'
    lftp -e "
    open $HOST
    user $USER $PASS
    mirror --verbose --continue $RCD
    bye
    "

To sync only certain folders, use the following sciprts:

  1. #!/bin/bash
    HOST='<ftp host>'
    USER='<ftp user>'
    PASS='<password>'
    RCD='<remote directory to sync>'
    lftp -e "
    open $HOST
    user $USER $PASS
    mirror --verbose --continue --exclude '.*' --exclude '.*/' --include '<folder1>' --include '<folder2>' $RCD
    bye
    "

To have sync overnight even when logged out, use the command nohup bash sync.sh > sync.log.

Networking

ArchLinux - Setting Up Fortinet SSL VPN

  1. Install ppp, openfortivpn and networkmanager's fortinet plugin package: sudo pacman -Syu ppp openfortivpn networkmanager-fortisslvpn
  2. Get certificate digest by running: sudo openfortivpn <IP Address>:<Port> --username=<username>
  3. Enable kernel module: modprobe ppp_generic
  4. Reconnect with openfortivpn: sudo openfortivpn <IP Address>:<Port> --username=<username> --trusted-cert <certificate digest>
  5. Now you can connect to the VPN by creating a new Fortinet SSLVPN (fortisslvpn) connection:
    • Enter the Gateway in the format <IP Address>:<Port>
    • Your username and password
    • Finally click "Advanced" and enter the certificate digest into Trusted certificate field

References

Desktop Environments

Everthing to do about Desktop Environments, including LXDE, XFCE, KDE and Gnome

Desktop Environments

Getting Cursor Pointer Theme for LXDE

  1. Installing the package xcursor-themes
  2. Then go to Preferences > Customize Look and Feel
  3. Select your cursor pointer theme under Mouse Cursor tab
Desktop Environments

LXDE Volume Keybinding

Add the following lines to ~/.config/openbox/lxde-rc.xml:

<keybind key="XF86AudioMute"> 
  <action name="Execute"> 
    <command>amixer sset Master toggle</command> 
  </action> 
</keybind> 
<keybind key="XF86AudioRaiseVolume"> 
  <action name="Execute"> 
    <command>amixer sset Master 5%+</command> 
  </action> 
</keybind> 
<keybind key="XF86AudioLowerVolume"> 
  <action name="Execute"> 
    <command>amixer sset Master 5%-</command> 
  </action>
</keybind>

Issue command => openbox --restart

Desktop Environments

LXDE Blueproximity Settings

Locking Command: xscreensaver-command -activate
Unlock Command: pkill xscreensaver
Proximity Command: xscreensaver-command -time || daemonize /usr/bin/xscreensaver -no-splash
Daemonize Utility: To stop blueproximity from hanging when using the proximity command, it requires the daemonize command (http://software.clapper.org/daemonize/). Using "xscreensaver -no-splash &" or "xscreensaver -no-splash" will cause blueproximity to hang.

Desktop Environments

Auto Suspend USB

There are 2 settings that needs to changed:

  1. Add usbcore.autosuspend=0 usbcore.autosuspend_delay_ms=-1 to /boot/grub/grub.cfg kernel param
  2. Disable monitor power manager control in xfce4-power-manager settings
  3. Install acpid
  4. Add the following udev rules to /etc/udev/rules.d/99-usb-autosuspend.rules:
    ACTION=="add", SUBSYSTEM=="usb", TEST=="power/control",
ATTR{power/control}="on"
ACTION=="add", SUBSYSTEM=="usb", TEST=="power/autosuspend",
ATTR{power/autosuspend}="0"
ACTION=="add", SUBSYSTEM=="usb", TEST=="power/autosuspend_delay_ms",
ATTR{power/autosuspend_delay_ms}="-1"
Desktop Environments

LXDE Visual Artifacts when Switching from Desktops with Chrome

LXDE Visual Artifacts when Switching Desktops. Install a composite manager will remove the artifacts, below is a list of composite managers:

Install compton package Add @compton -b to the end of /etc/xdg/lxsession/LXDE/autostart

References:

  1. https://wiki.archlinux.org/index.php/Compton

Scripts

Contains all the script I used for my administration

Scripts

Script - Backup Script for Home Directories and MySQL Databases

#!/bin/sh

# Home directory to backup must be absolute path, with trailing slash 
home_dir='/home/' 
# Target backup directory, must be absolute path, with trailing slash 
backup_dir='/backups/'

# Database user 
db_user='root' 
# Database Password 
db_pwd=''

cd "$home_dir" 
# Get list of users based on home dir 
users=`find . -maxdepth 1 -type d \( -iname "*" ! -iname "backups" ! -iname "lost+found" \) -exec echo {} \; | sed "s#./##" | grep -v '^/home$'`
for user in $users; do 
    # Skip if user string is empty 
    if [ $user == "" -o $user == ".." -o $user == "." ]; then 
        continue 
    fi 
    # Archive all files in directory 
    archive="$backup_dir`date +%Y%m%d`.$user.tar.gz" 
    tar czf "$archive" "$user" 
done

# Database backup script 
if [ ! -z "$db_pwd" ]; then 
    databases=`mysql -u$db_user -p$db_pwd -e "SHOW DATABASES;" | tr -d "| " | grep -v Database` 
else
    databases=`mysql -u$db_user -e "SHOW DATABASES;" | tr -d "| " | grep -v Database` 
fi 
cd $backup_dir 
for db in $databases; do 
    if [[ "$db" != "information_schema" ]] && [[ "$db" != "performance_schema" ]] && [[ "$db" != "mysql" ]] && [[ "$db" != _* ]] ; then 
        sql="`date +%Y%m%d`.$db.sql" 
        echo "Dumping database: $db" 
        if [ -z "$db_pwd" ]; then 
            mysqldump -u$db_user $db > $sql 
        else 
            mysqldump -u$db_user -p$db_pwd $db > $sql 
        fi 
        tar -czf "`date +%Y%m%d`.$db.sql.tar.gz" $sql 
        rm $sql 
    fi 
done

NOTE: Add this to cronjob to delete backups older than 90 days: find . -type d -mtime +90 -exec rm {}\;

Scripts

Script - MySQL Dump Databases Separated by DB Name

#!/bin/bash

DUMP_EXEC="mysqldump" #path to mysqldump
MYSQL_EXEC="mysql" #path to mysql

MYSQL_USER="root" #db user
MYSQL_PASSWORD="" #db password

databases="$MYSQL_EXEC -u$MYSQL_USER"
if [ "$MYSQL_PASSWORD" ]; then
    databases="$databases -p$MYSQL_PASSWORD"
fi

eval "$databases -e 'show databases'" | while read dbname
do
    if [ "$dbname" ]; then
        echo "Dumping database: $dbname"
        dumpScript="$DUMP_EXEC --max_allowed_packet=1G -u$MYSQL_USER"
        if [ "$MYSQL_PASSWORD" ]; then
            dumpScript="$dumpScript -p$MYSQL_PASSWORD"
        fi
        eval "$dumpScript --complete-insert '$dbname' > '$dbname.sql'"
    fi
done
Scripts

Script - Move Infected Emails to Quarantine and Notify Users

The following script will do the following:

  1. Parse email headers from ClamScan Results
  2. Move infected email to $QUARANTINE folder
  3. Construct email messages
  4. Email the users who has any infected emails in their mailbox
#!/bin/bash

ADMIN="admin@domain.com" # Admin email
QUARANTINE="/quarantine/directory/" # Quarantine folder with trailing slash
HEADER="The emails listed has been moved to quarantine and will be deleted after 30 days. If you have any concerns, please contact the server administrator" 
FOOTER="This is an automated email through ClamScan results, please find the script details at 'https://wiki.twcloud.tech/books/linux/page/script---move-infected-emails-to-quarantine-and-notify-users'"

# Getting email information
[ -z "$1" ] && echo "File parameter missing" && exit 1
[ ! -f "$1" ] && echo "File not found / not a regular file" && exit 1
declare -A emails
while read i; do
    file=`echo "$i" | sed -e 's/\:\ .*FOUND//'`
    if [ ! -f "$file" ]; then
        continue
    fi
    infection=`echo "$i" | sed -n 's/\:\ .*FOUND//'`
    to=`cat "$file" | grep -m 1 "^Envelope-to\:\s\+" | sed 's/Envelope-to\:\ //' | grep -EiEio '\b[A-Z0-9._%+-]+@[A-Z0-9.-]+\.[A-Z]{2,4}\b'`
    # Try find To: header if Envelope-to: not found
    [[ -z "$to" ]] && to=`cat "$file" | grep -m 1 "^To\:\s\+" | sed 's/To\:\ //' | grep -EiEio '\b[A-Z0-9._%+-]+@[A-Z0-9.-]+\.[A-Z]{2,4}\b'`
    from=`cat "$file" | grep -m 1 "^From\:\s\+" | sed 's/From\:\ //'`
    d=`cat "$file" | grep -m 1 "^Delivery-date\:\s\+" | sed 's/Delivery-date\:\ //'`
    subject=`cat "$file" | grep -m 1 "^Subject\:\s\+" | sed 's/Subject\:\ //'`

    # Send empty "$to" to admin
    [[ -z "$to" ]] && to="$ADMIN"

    # Construct email message
    [[ -z "${emails[$to]}" ]] && emails[$to]="$HEADER"
    emails[$to]="${emails[$to]}\n\nFrom: $from\nDate: $d\nSubject: $subject"

    # Move emails to quarantine
    mv "$file" "$QUARANTINE"
done < "$1"

# Notify email users that the emails are sent to quarantine
for k in "${!emails[@]}"; do
    echo -e "${emails[$k]}\n----------\n$FOOTER" | mail -s "Infected emails quarantined" -c "$ADMIN" $k
done
Scripts

Delete Old Emails and Notify User

ADMIN="admin@domain.com" # Admin email
DOMAIN="domain.com" # Domain name
HEADER="The emails listed has been moved to trash, and will be deleted on the 31st December every year" 
FOOTER="This is an automated email generated through a script, please find the script details at 'https://wiki.twcloud.tech/books/linux/page/delete-old-emails-and-notify-user'"
REMOVE_FILE_AGE=60 # File age to remove in days
USER="user" # Username used to login to the hosting account
TRASH_FOLDER="/home/$USER/trashed_emails/" # Trash folder with trailing slash

# Getting email information
[ -z "$1" ] && echo "Email user parameter missing" && exit 1
[ ! -d "/home/$USER/mail/$DOMAIN/$1/cur" ] && echo "Email not found" && exit 1
# Declarations
declare -A emails

for file in $(find "/home/$USER/mail/$DOMAIN/$1/cur" -type f -mtime +${REMOVE_FILE_AGE} -print); do
    if [ ! -f "$file" ]; then
        continue
    fi
    to="$1@$DOMAIN"
    from=`cat "$file" | grep -m 1 "^From\:\s\+" | sed 's/From\:\ //'`
    d=`cat "$file" | grep -m 1 "^Delivery-date\:\s\+" | sed 's/Delivery-date\:\ //'`
    subject=`cat "$file" | grep -m 1 "^Subject\:\s\+" | sed 's/Subject\:\ //'`

    # Send empty "$to" to admin
    [[ -z "$to" ]] && to="$ADMIN"

    # Construct email message
    [[ -z "${emails[$to]}" ]] && emails[$to]="$HEADER"
    emails[$to]="${emails[$to]}\n\nFrom: $from\nDate: $d\nSubject: $subject"

    # Move emails to trash
    mv "$file" "$TRASH_FOLDER"
done

# Notify email users that the emails are sent to trash
for k in "${!emails[@]}"; do
    echo -e "${emails[$k]}\n----------\n$FOOTER" | mail -s "Inbox Cleared" -c "$ADMIN" $k
done

Server Software

Server software configuration and installation procedures such as Apache, and Postfix

Server Software

Apache Option FollowSymLinks not allowed here Error

Apache htaccess Option FollowSymLinks not allowed here error: 

find /home -name ".htaccess" -type f -exec sed -i '/FollowSymLinks/SymLinksIfOwnerMatch/g' {} ";"
Server Software

Migrating Self-Signed SSL Certificate to LetsEncrypt Certificate

Download Let's Encrypt Client

  1. sudo -s
  2. git clone https://github.com/letsencrypt/letsencrypt /opt/letsencrypt

Update Apache Configuration

Let's Encrypt does not detect multiple virtual host in a single file, so if you have multiple virtual hosts in a single file, you need to separate it and update the configuration for SSL only. Then redirect all plain-text traffic to SSL using a single virtual host.

Create a new virtual host in /etc/httpd/conf.d/redirect_ssl.conf to redirect plain-text traffic to SSL, replace all <domain>to your TLD, such as example.com:

  1. <VirtualHost *:80>
  2. ServerName <domain>
  3. ServerAlias *.<domain>
  4. RewriteEngine on
  5. RewriteRule ^/(.*) https://%{HTTP_HOST}/$1 [NC,R=301,L]
  6. </VirtualHost>

Setup SSL Certificates

  1. cd /opt/letsencrypt
  2. ./letsencrypt-auto --apache -d <domain> -d www.<domain> -d <subdomain>.<domain>

Replacing <domain> with your domain, subsequent subdomains can be specified with -d option.

Restart Apache and Test

  1. systemctl restart httpd

(Optional) Renewing SSL Certificates

Let's Encrypt issue 90 days validity certificates, but you can however, renew it earlier in case errors occurred.

To renew the certificates, simply use the following command:

  1. /opt/letsencrypt/letsencrypt-auto renew

If you have just created a new certificate, Let's Encrypt will never issue you a new one, it will only issue a new certificate for your domains if the validity period is less than 30 days, so, you can create a cronjob to try and renew the certificate every day, week or month, in case anything goes wrong with your certificate.

To setup cronjob to automatically renew certificate, enter command crontab -e to create a new cronjob and add the following line:

  1. 0 3 * * 1 /opt/letsencrypt/letsencrypt-auto renew >> /var/log/le-renew.log

The cronjob above will run on every monday at 3 A.M., it will append any output from /opt/letsencrypt/letsencrypt-autoto /var/log/le-renew.log. Please refer to the reference for more info on Linux cronjobs.

References

  1. Digital Ocean Article
  2. Let's Encrypt Article
  3. Cronjob Format
Server Software

LAMP Stack Upgrade Issues

"Table Doesn't Exists" After MySQL/MariaDB Upgrade

Paste MySQL data directory to upgraded data directory, containing ibdata1, ib_logfile0 and ib_logfile1, in lampp, it's /opt/lampp/var/mysql:

  1. sudo cp /opt/lampp_backup/var/mysql /opt/lampp/var/mysql
  2. sudo chown -R mysql:mysql /opt/lampp/mysql
Server Software

Standard Installation Procedures for LAMP Stack on CentOS 7

1. System Upgrade

  1. yum -y update

2. Install Required Software

  1. yum -y install git policycoreutils-python httpd mariadb mariadb-server php-mysql php-gd php-ldap php-odbc php-pear php-xml php-xmlrpc php-mbstring php-snmp php-soap curl curl-devel

3. Setup MySQL Server

  1. mysql_secure_installation

4. Start and Enable All Services

  1. systemctl enable httpd
  2. systemctl enable mariadb
  3. systemctl start httpd
  4. systemctl start mariadb

5. Open Firewall Ports

  1. firewall-cmd --permanent --zone=public --add-service=http
  2. firewall-cmd --permanent --zone=public --add-service=https
  3. firewall-cmd --permanent --zone=public --add-port=<ssh_port>/tcp
  4. firewall-cmd --reload

6. Change SSH Port

  1. vim /etc/ssh/sshd_config #and append 'Port <ssh_port>'
  2. semanage port -a -t ssh_port_t -p tcp <ssh_port>
  3. systemctl restart sshd

7. Enable Shutdown Button

Edit /etc/systemd/logind.conf and uncomment the following 2 lines:

  1. PowerKeyIgnoreInhibited=no
  2. HandlePowerKey=poweroff

8. Reboot System

  1. reboot

(HP MicroServer Only)

Edit /etc/default/grub and append clocksource=hpet nolapic to the end of GRUB_CMDLINE_LINUX variable.

Server Software

Slow Loading on Ownloud 8

Change /var/www/html/owncloud/config/config.php database host to 127.0.0.1 instead of localhost

Server Software

Postfix and Dovecot Configuration

Installation

  1. hostnamectl set-hostname mail.<domain>.<tld>
  2. yum -y install postfix dovecot

Postfix Configuration

  1. Append the following to /etc/postfix/main.cf:

    1. myhostname = mail.<domain>.<tld>
    2. mydomain = <domain>.<tld>
    3. myorigin = $mydomain
    4. home_mailbox = mail/
    5. mynetworks = 127.0.0.0/8 <domain IP>
    6. inet_interfaces = all
    7. mydestination = $myhostname, localhost.$mydomain, localhost, $mydomain
    8. smtpd_sasl_type = dovecot
    9. smtpd_sasl_path = private/auth
    10. smtpd_sasl_local_domain =
    11. smtpd_sasl_security_options = noanonymous
    12. broken_sasl_auth_clients = yes
    13. smtpd_sasl_auth_enable = yes
    14. smtpd_recipient_restrictions = permit_sasl_authenticated,permit_mynetworks,reject_unauth_destination
    15. smtp_tls_security_level = may
    16. smtpd_tls_security_level = may
    17. smtp_tls_note_starttls_offer = yes
    18. smtpd_tls_loglevel = 1
    19. smtpd_tls_key_file = /etc/letsencrypt/live/<domain>.<tld>/privkey.pem
    20. smtpd_tls_cert_file = /etc/letsencrypt/live/<domain>.<tld>/fullchain.pem
    21. smtpd_tls_received_header = yes
    22. smtpd_tls_session_cache_timeout = 3600s
    23. smtpd_use_tls=yes
    24. tls_random_source = dev:/dev/urandom
    25. virtual_alias_domains = <domain>.<tld>
    26. virtual_alias_maps = hash:/etc/postfix/virtual

  2. Find and uncomment the following lines in /etc/postfix/main.cf:

    1. #inet_interfaces = localhost
    2. #mydestination = $myhostname, localhost.$mydomain, localhost

  3. Append the following lines to /etc/postfix/master.cf:

    1. submission inet n - n - - smtpd
    2. -o syslog_name=postfix/submission
    3. -o smtpd_sasl_auth_enable=yes
    4. -o smtpd_recipient_restrictions=permit_sasl_authenticated,reject_unauth_destination
    5. -o milter_macro_daemon_name=ORIGINATING
    6. smtps inet n - n - - smtpd
    7. -o syslog_name=postfix/smtps
    8. -o smtpd_sasl_auth_enable=yes
    9. -o smtpd_recipient_restrictions=permit_sasl_authenticated,reject_unauth_destination
    10. -o milter_macro_daemon_name=ORIGINATING

  4. Make sure that the following is present in /etc/postfix/main.cf:

    1. alias_maps = hash:/etc/aliases

  5. Edit and add the desired email address to /etc/postfix/virtual such as the following:

    1. info@<domain>.<tld> admin
    2. webmaster@<domain>.<tld> admin

  6. Create a map database: postmap /etc/postfix/virtual

Dovecot Configuration

  1. Find and modify the following lines in /etc/dovecot/conf.d/10-master.conf:

    1. # Postfix smtp-auth
    2. unix_listener /var/spool/postfix/private/auth {
    3. mode = 0660
    4. user = postfix
    5. group = postfix
    6. }

  2. Find and modify the following lines in /etc/dovecot/conf.d/10-auth.conf:

    1. auth_mechanisms = plain login

  3. Find and modify the following lines in /etc/dovecot/conf.d/10-mail.conf:

    1. mail_location = maildir:~/mail

  4. Find and modify the following lines in /etc/dovecot/conf.d/20-pop3.conf:

    1. pop3_uidl_format = %08Xu%08Xv

  5. Find and modify the following lines in /etc/dovecot/conf.d/10-ssl.conf:

    1. ssl_cert = </etc/letsencrypt/live/<domain>.<tld>/fullchain.pem
    2. ssl_key = </etc/letsencrypt/live/<domain>.<tld>/privkey.pem

Restart and Enable Services

  1. systemctl restart postfix
  2. systemctl enable postfix
  3. systemctl restart dovecot
  4. systemctl enable dovecot

Open Firewall Ports

  1. firewall-cmd --permanent --add-service=smtp
  2. firewall-cmd --permanent --add-port=587/tcp
  3. firewall-cmd --permanent --add-port=465/tcp
  4. firewall-cmd --permanent --add-port=110/tcp
  5. firewall-cmd --permanent --add-service=pop3s
  6. firewall-cmd --permanent --add-port=143/tcp
  7. firewall-cmd --permanent --add-service=imaps
  8. firewall-cmd --reload

Configure DNS

  1. Add an A record for the mail server:

    1. name = mail.<domain>.<tld>`
    2. IP = <mail server IP>

  2. Add an MX record:

    1. Hostname = mail.<domain>.<tld>
    2. Priority = 5

  3. Add the following TXT records:

    1. Name = @
    2. Text = "v=spf1 ip4:<domain IP> ~all"
    4. Name = _dmarc.<domain>.<tld>
    5. Text = v=DMARC1; p=none

  4. Add PTR record for <domain>.<tld>

  5. Finally, test your email at https://www.mail-tester.com/

Notes on Using Let's Encrypt for SSL

Make sure that Encryption is set to STARTTLS when configuring mail clients

References

  1. Krizna Article
  2. Ubuntu Postfix Alias Configuration
Server Software

Install RethinkDB on CentOS 7

Installing RethinkDB

sudo wget http://download.rethinkdb.com/centos/7/`uname -m`/rethinkdb.repo -O /etc/yum.repos.d/rethinkdb.repo
sudo yum install rethinkdb

Create Service File

Create the service file, /usr/lib/systemd/system/rethinkdb@.service with the following content:

[Unit]
Description=RethinkDB database server for instance '%i'

[Service]
User=rethinkdb
Group=rethinkdb
ExecStart=/usr/bin/rethinkdb serve --config-file /etc/rethinkdb/instances.d/%i.conf
KillMode=process
PrivateTmp=true

[Install]
WantedBy=multi-user.target

Make sure that it has a permission of 644: chmod 644 /usr/lib/systemd/system/rethinkdb@.service

Creating a Rethink DB Instance

  1. Create the RethinkDB data directory: rethinkdb create -d /path/to/your/rethinkdb/directory
  2. Set the ownership to RethinkDB user: sudo chown -R rethinkdb.rethinkdb /path/to/your/rethinkdb/directory
  3. Copy RethinkDB sample config file: sudo cp /etc/rethinkdb/default.conf.sample /etc/rethinkdb/instances.d/instance1.conf
  4. Edit /etc/rethinkdb/instances.d/instance1.conf, the line with directory= must be changed to point to your Rethink DB data directory.

Start RethinkDB Instance

in this case would be instance1:

sudo systemctl enable rethinkdb@<name_instance>
sudo systemctl start rethinkdb@<name_instance>

References

RethinkDB Startup Doc

Server Software

Turtl API Server and Client Installation CentOS 7

Turtl API

Clone and Configure Turtl API

  1. Create a user for turtl API: sudo useradd turtl
  2. Switch user to turtl: sudo su turtl
  3. Change directory to turtl's home: cd ~
  4. Install Clozure CL
  5. Install RethinkDB and create an instance for Turtl API
  6. Install libuv: sudo yum install libuv
  7. Clone Turtl repo: git clone https://github.com/turtl/api.git
  8. Copy Turtl API config: cp config/config.default.lisp config/lisp
  9. Edit and configure config/config.lisp, make sure to update the following parameters:
    (defvar *local-upload* "<local upload directory>"
(defvar *local-upload-url* "<upload url>"

Setup Up Service

Create a service file at /usr/lib/systemd/system/turtl.service with the following entry:

[Unit]
Description=Turtl API Server

[Service]
User=turtl
Group=turtl
ExecStart=/usr/local/bin/ccl64 --load /home/turtl/api/start.lisp
KillMode=process

[Install]
WantedBy=multi-user.target

Start and enable the service:

sudo systemctl start turtl
sudo systemctl enable turtl

(OPTIONAL) Configure Reverse Proxy in Apache

Create httpd virtual host configuration /etc/httpd/conf.d/turtl.conf with the following content, make sure to change <turtl domain> to your own domain name:

<VirtualHost *:80>
    #Server name configuration
    ServerName <turtl domain>
    ServerAdmin webmaster@<turtl domain>

    #Proxy configuration
    ProxyPreserveHost on
    ProxyRequests off
    ProxyPass / https://wiki.twcloud.tech:8181/
    ProxyPassReverse / https://wiki.twcloud.tech:8181/

    #Logging configuration
    ErrorLog /var/log/httpd/turtl.err
    LogLevel warn
</VirtualHost>

(OPTIONAL) Restrict User Registration

Add the following lines in your Turtl API Virtual Hosts configuration:

    #Restrict Registration
    <LocationMatch  "^/users[/]?$">
        AuthType Basic
        AuthName "Restricted"
        AuthUserFile /home/turtl/.htpasswd
        Require valid-user 
    </LocationMatch>

Then generate a .htpasswd password file in /home/turtl: sudo htpasswd -c /etc/apache2/.htpasswd <whatever username>. Make sure that it's in the right permission and owner: chmod 640 /home/turtl/.htpasswd && chown turtl:apache /home/turtl/.htpasswd

Installing JS Client

  1. Clone turtl/js repo to webserver webroot: sudo mkdir /var/www/turtl && cd /var/www/turtl && sudo git clone https://github.com/turtl/js.git .
  2. Install NodeJS dependencies: npm install
  3. Copy default config: cp config/config.js.default config.js
  4. Edit config/config.js
  5. Update owner and group: chown -R apache:apache .
  6. Generate assets: make

Software Development

All about software development tricks on Linux

Software Development

Creating War File in Linux

  1. CD to war directory in the project folder
  2. Execute jar -cvf .war *
Software Development

Standard Procedures for CakePHP Application Deployment

1. Clone Source File

  1. git clone <git url>

2. Setup Database

  1. mysql -uroot -p
  2. create database <database name>;
  3. grant all on <database name>.* to '<id>'.'localhost' identified by '<password>';
  4. cd <path/to/cakephp>/app
  5. Console/cake schema create
  6. Console/cake schema update -s <update number found in app/Config/Schema/>

3. Setup PHP

Edit /etc/php.ini and add the following line:

  1. date.timezone = "Asia/Kuala_Lumpur"

4. Allow Write Access to tmp

  1. chmod -R 777 app/tmp/

5. Setup Apache

Edit /etc/httpd/conf/conf.d and change AllowOverride None to AllowOverride All in <Directory "/var/www/html"> tag. Then, restart httpd:

  1. sudo systemctl restart httpd

(OPTIONAL) SELinux

  1. sudo setsebool -P allow_httpd_anon_write on
  2. sudo setsebool -P allow_httpd_sys_script_anon_write on
  3. sudo setsebool -P httpd_unified 0
  4. sudo chcon -R -t httpd_sys_rw_content_t <path_to_cakephp_app>/app/tmp/
Software Development

Installing Clozure CL and QuickLisp on CentOS 7

Download Clozure CL

Open up terminal and enter the command: svn co http://svn.clozure.com/publicsvn/openmcl/release/1.11/linuxx86/ccl Where linuxx86 is one of:

Download and Install QuickLisp

  1. Download QuickLisp from https://beta.quicklisp.org/quicklisp.lisp
  2. Enter the command: ./ccl/lx86cl64 --load /path/to/quicklisp.lisp
  3. In the CCL prompt enter: (quicklisp-quickstart:install)(ql:add-to-init-file)

Creating Scripts to Run CCL

  1. Edit ./ccl/scripts/ccl and ./ccl/scripts/ccl64 to change CCL_DEFAULT_DIRECTORY=/usr/local/src/ccl line to CCL_DEFAULT_DIRECTORY=~/ccl
  2. Copy the scripts to /usr/local/bin directory: sudo cp ./ccl/scripts/ccl* /usr/local/bin/

References

Sound

Linux sound problems, configuration and installation

Sound

No Sound over Wine

Install lib32-alsa-plugins lib32-libpulse lib32-openal

Sound

E: [pulseaudio] module.c: Failed to load module "module-equalizer-sink" (argument: ""): initialization failed.

Symtoms

Starting pulseaudio will forever Establishing connection, pulseaudio -v will reveal the following errors:

W: [pulseaudio] module-equalizer-sink.c: module-equalizer-sink is currently unsupported, and can sometimes cause PulseAudio crashes, increased latency or audible artifacts.
W: [pulseaudio] module-equalizer-sink.c: If you're facing audio problems, try unloading this module as a potential workaround.
E: [pulseaudio] module-equalizer-sink.c: Master sink not found
E: [pulseaudio] module.c: Failed to load module "module-equalizer-sink" (argument: ""): initialization failed.
E: [pulseaudio] main.c: Module load failed.
E: [pulseaudio] main.c: Failed to initialize daemon.
I: [pulseaudio] main.c: Daemon terminated.

Solution

Start pulseaudio using Desktop Manager's autostart script, the following instruction is for LXDE:

  1. Create a desktop file on ~/.config/autostart/pulseaudio-equalizer.desktop
  2. Add the following lines:
[Desktop Entry]
Type=Application
Exec=bash -c 'pactl load-module module-equalizer-sink; pactl load-module module-dbus-protocol;'

References

Storage

Storage administration and tricks, including LVM, SCSi etc.

Storage

LVM Extending from New Physical Volume

Create new physical volume from new partition

  1. Use fdisk utility to create new partition
  2. pvcreate /dev/<new partition>
  3. pvs

Adding physical volume to volume group

  1. vgextend <volume group> /dev/<new partition>

Extending logical volume

  1. lvextend -L+<size><G or M> /dev/<volume group>/<lv name>
  2. #For XFS:
  3. xfs_grow /<mount_point>
  4. #For EXT4:
  5. resize2fs /<mount>/<point>

System

Linux system tools, administration and tips

System

ArchLinux Upgrade Issues

Error: key "ABCDE1282828181" could not be looked up remotely

Upgrade archlinux-keyring: pacman -S archlinux-keyring

Unable to get past login window after upgrading

This is caused by Nvidia driver being upgraded

nvidia-dkms: pacman -S nvidia-libgl

Failed to start load kernel modules after upgrade:

Possible causes:

System

CentOS Installation Issues

HP Microserver Gen 7

Kernel Panic on Boot (Both Live USB and New Installation)

Add the following lines to the kernel boot parameters: nolapic clocksource=hpet

Blank Screen on Startup

Append nomodeset to kernel param

System

Changing Default S2RAM to USWSUSP Suspend Module

If you have any issues to suspend your laptop e.g. suspend command doesn't work on your laptop, try changing the default sleep module to uswsusp:

  1. Edit /etc/pm/config.d/module and add the following line: SLEEP_MODULE=uswsusp

  2. Edit /etc/pm/config.d/defaults and add the following line: S2RAM_OPTS="-f"

  3. Reboot and try to let her sleep.

References

System

Fixing Incorrect Lid State by Hacking DSDT

When I install a Linux distro to my VAIO notebook, I found that there is an annoying bug with the lid switch. It does not get updated whenever I suspend on lid close, it means cat /proc/acpi/button/lid/LID/state will output state: close. When I close the lid again, it won't suspend, instead, it will change the state to open. So in order for it to suspend again on lid close after the first suspend, I have to close it, reopen the lid and close it again.

I have tried installing Linux Mint, Fedora, Fuduntu and Xubuntu, but it is not fixed in any of the distros. So, I don't think it is distro problems. While researching this issues (which I spent two full days), I found that Linux got an amazing feature that enable users to dynamically loading DSDT at boot time, there is no need to update the BIOS. So here's the instuctions:

  1. Install iasl using yum, apt-get or whatever package management you are using.

  2. Extract DSDT:

    $ sudo cat/sys/firmware/acpi/tables/DSDT > dsdt.aml

  3. Disassemble dsdt.aml using the following command, this should create a new file dsdt.dsl:

    $ iasl -d dsdt.aml

  4. Compile it using:

    $ iasl -tc dsdt.dsl

  5. Fix any compiler errors, warnings and remarks. On my machine, the output is:

    dsdt.dsl  1352:                         And (CTRL, 0x1E)
Warning  1106 -                                 ^ Result is not used, operator has no effect

dsdt.dsl  1584:                     0x00000000,         // Length
Error    4122 -                              ^ Invalid combination of Length and Min/Max fixed flags

dsdt.dsl  2443:                                 Name (_T_0, 0x00)
Remark   5111 -            Use of compiler reserved name ^  (_T_0)

dsdt.dsl  2521:                                 Name (_T_0, 0x00)
Remark   5111 -            Use of compiler reserved name ^  (_T_0)

    a. The first one is on line 1352 can be fixed simply by changing And (CTRL, 0x1E) to And (CTRL, 0x1E, CTRL).
    b. The second one is on line 1584, the length should be Range Maximum - Range Minimum + 1, on my machine, so fire up a hex calculator and start subtracting. On my machine, it's 0xE0000000 (0xDFFFFFFF - 0x00000000 + 0x00000001).
    c. The third and fourth line is on line 2443 and 2521, because it uses a reserved name, simply replacing all instances of _T_0 to T_0 will stop the complaints. In vim, it is as simple as issuing :%s/_T_0/T_0/g in command mode.

  6. Once everything is fixed (no errors, warning or remarks), add the following line to _WAK method, simply search for _WAK in dsdt.dsl:

    If (LNotEqual (0x00, LIDS))
{
Store (0x00, LIDS)
Notify (\_SB.LID, 0x80)
}

    NOTE 1: You might need to change \_SB.LID to match your path to LID method or on some machine LID0. Method name is preceded by an _ (underscore), so you can search for _LID in dsdt.dsl. After you found it, you have to determine the scope, scroll up until you found Scope keyword that your LID or LID0 method belongs to, inside the bracket is the scope name. It may be in more than one scope, so, it might be \_PCI0.SB.LID. If you specify an incorrect path to LID method, you will receive the following error:

    dsdt.dsl 300: Notify (LID, 0x80)
Error 4068 - ^ Object is not accessible from this scope (LID_)

    NOTE 2: What this function does is just to update the lid state once it is resumed from sleep. According to the ACPICA documentation, _WAK method is called by AcpiLeaveSleepState() function of ACPI. If the lid is open, the LIDS variable is 0x00, or 0x01 otherwise. So these few lines translate to "if lid state is not open (closed), change lid state to open and call LIDmethod".

  7. Compile it using iasl -tc dsdt.dsl.

  8. If no errors, warnings or remarks, add the following lines to /etc/grub.d/01_acpi:

    # Uncomment to load custom ACPI table
GRUB_CUSTOM_ACPI="/boot/dsdt.aml"

# DON'T MODIFY ANYTHING BELOW THIS LINE!

prefix=/usr
exec_prefix=${prefix}
libdir=${exec_prefix}/lib

. /usr/share/grub/grub-mkconfig_lib
#. ${libdir}/grub/grub-mkconfig_lib

# Load custom ACPI table
if [ x${GRUB_CUSTOM_ACPI} != x ] && [ -f ${GRUB_CUSTOM_ACPI} ] \
   && is_path_readable_by_grub ${GRUB_CUSTOM_ACPI}; then
   echo "Found custom ACPI table: ${GRUB_CUSTOM_ACPI}" >&2
   prepare_grub_to_access_device `${grub_probe} --target=device 
${GRUB_CUSTOM_ACPI}` | sed -e "s/^/  /"
   cat << EOF
acpi (\$root)`make_system_path_relative_to_its_root 
${GRUB_CUSTOM_ACPI}`
EOF
fi

  9. Add executable bit to it:

    $ sudo chmod +x /etc/grub.d/01_acpi

  10. Copy the new dsdt.aml to /boot:

    $ sudo cp dsdt.aml /boot

  11. Regenerate grub.cfg:

    $ sudo grub2-mkconfig -o /boot/grub2/grub.cfg
  12. Reboot

References

System

JournalD Administration

Optimizing JournalD Disk Space Usage

Edit /etc/systemd/journald.conf and change the following line:

SystemMaxUse=200M

To check disk space used by journald: journalctl --disk-usage

System

Linux on Macbook Administration

Blessing the Linux Kernel

  1. Boot into Mac Recovery
  2. Start terminal and enter:
  3. bless --folder /Volumes/ARCH_EFI/EFI/arch/grub/ --file /Volumes/ARCH_EFI/EFI/arch/grub/grubx64.efi

Changing Apple keyboards (Macbook or USB) fnmode in Linux

Changing it temporarily, as root:

echo 2 > /sys/module/hid_apple/parameters/fnmode

Changing it Permanently:

Edit /etc/modprobe.d/hid_apple.conf and add the following line:

options hid_apple fnmode=2
System

SELinux - Services Blocked by SELinux

SELinux Blocked Apache Access to Files

setsebool -P httpd_unified 1
sudo /sbin/restorecon -R /var/www/html

VSFTPD OOPS Error

Issue the following command: setsebool -P ftp_home_dir 1

SSH bind port error permission denied

Issue the following command: semanage port –a –t ssh_port_t –p tcp 1234

Permission denied HTTP Error 403

Issue the following command: chcon -R --reference=/var/www /path/to/webroot

SELinux Denied HTTPD Access to MYSQLD on 127.0.0.1

  1. grep mysqld /var/log/audit/audit.log | audit2allow -M mysqld
  2. semodule -i mysqld.pp

SELinux Denied FTP Access to SMB Share

  1. Try to login with ncftp first and you will see the error "OOPS: cannot change directory: /path/to/samba_share"
  2. Execute command: su -c "grep ftpd_t /var/log/audit/audit.log | allow2audit -M ftpd_smb && semodule -i ftpd_smb"
  3. Try to login again with ncftp and ls command will return empty list a although it isn't
  4. Execute command: su -c "grep ftpd_t /var/log/audit/audit.log | allow2audit -M ftpd_smb && semodule -i ftpd_smb"
  5. Execute command => sudo setsebool -P allow_ftpd_full_access on
  6. Execute command => sudo setsebool -P ftp_home_dir on

Owncloud Custom Data Directory Denied

Assume owncloud data directory: /var/data

Install policycoreutils-python
/etc/init.d/restorecond start
chkconfig restorecond on
semanage fcontext -a -t httpd_sys_content_t '/var/data(/.*)?' 
restorecon -Rv /var/data
System

Standard CentOS Workstation Setup

Install GUI (MATE Desktop)

  1. sudo yum install epel-release
  2. sudo yum groupinstall 'X Window System'
  3. sudo yum groupinstall 'MATE Desktop'
  4. sudo systemctl isolate graphical.target
  5. sudo systemctl set-default graphical.target

Install Printer

  1. sudo yum install cups
  2. sudo yum groupinstall "Development Tools"
  3. sudo systemctl enable cups
  4. sudo systemctl start cups
  5. sudo yum install foomatic

Install drivers for the printer available at Open Printing

Optional - GUI WiFi Support

  1. sudo yum install NetworkManager-wifi

Ansible

Contains everything on Ansible IT automation tool, playbooks and tricks

Ansible

Playbook - Clearing Users' Data Files in a Group of Windows Machines

The playbook below will remove all users' data in a computer that belongs in an inventory group. Below is a list of steps that this playbook will do:

  1. Disable and remove the target user
  2. Reboot to remove any file locks from the logged in user
  3. Remove any files in the user's directory, skipping symbolic links
  4. Re-create a public user with the same username and empty password that cannot be changed
  5. Enable auto login for the user so that new machine will be configured for auto login as well
  6. Reboot computer to enable the configuration

The playbook is as follows, please change the variables encapsulated in < > with the desired values:

---
- hosts: <inventory group / host>
  tasks:
  - name: remove user account
    win_user:
      name: <username>
      account_disabled: yes
      state: absent
  - name: reboot
    win_reboot:
      msg: "Scheduled reset started, windows will reboot in 90 seconds"
      pre_boot_delay: 90
  - name: remove any files in the folder tree
    ignore_errors: yes
    win_shell: |
      $Path = "C:\Users\<username>"
      Remove-Item "$Path" -Force -Recurse -ErrorAction SilentlyContinue
      if (Test-Path "$Path" -ErrorAction SilentlyContinue)
      {
          $folders = Get-ChildItem -Path $Path -Directory -Force -ErrorAction SilentlyContinue
          ForEach ($folder in $folders)
          {
              Remove-Tree $folder.FullName -Force -ErrorAction SilentlyContinue
          }

          $files = Get-ChildItem -Path $Path -File -Force
          ForEach ($file in $files)
          {
              Remove-Item $file.FullName -Force -ErrorAction SilentlyContinue
          }

          if (Test-Path "$Path" -ErrorAction SilentlyContinue)
          {
              Remove-Item $Path -Force -ErrorAction SilentlyContinue
          }
      }
  - name: re-add user account
    win_user:
      name: <username>
      state: present
      groups: Users
      user_cannot_change_password: yes
      password_expired: no
      password_never_expire: yes
  - name: enable auto logon
    win_shell: |
      Set-ItemProperty 'HKLM:\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon' -Name 'AutoAdminLogon' -Value '1'
      Set-ItemProperty 'HKLM:\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon' -Name 'DefaultUsername' -Value '<default username>'
      Set-ItemProperty 'HKLM:\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon' -Name 'DefaultPassword' -Value ''
  - name: reboot to apply new settings
    win_reboot:
      msg: "Scheduled reset completed, windows will reboot in 5 seconds"
      pre_boot_delay: 5

References:

Ansible

Playbook - Update Windows Machine (Windows Update Disabled)

This playbook will:

  1. Modify windows update service to manual in case the machine is set to disabled
  2. Start the windows update service
  3. Download and install the updates, reboot if required

The playbook is as follows, please change the encapsulated < > values to the desired values:

---
- hosts: <inventory group / hosts>
  tasks:
  - name: change windows update service to manual
    win_shell: Set-Service wuauserv -StartupType Manual
  - name: start windows update service
    win_shell: Start-Service wuauserv
  - name: download and install updates
    win_updates:
      reboot: yes
Ansible

Playbook - Initiate Clamscan on Machines with ClamWin Installed

This playbook will initiate a full scan on all computers using Clamscan that is installed through ClamWin:

---
- hosts: <inventory group / hosts>
  tasks:
  - name: full computer scan
    win_command: '"C:\Program Files (x86)\ClamWin\bin\clamscan.exe" -rv --move=C:\ProgramData\.clamwin\quarantine\ --database=C:\ProgramData\.clamwin\db\ --log=C:\ProgramData\.clamwin\log\ClamScanLog.txt --enable-stats C:\'
Ansible

Playbook - Disable Windows Updates

This playbook will download disable_windows_update.ps1 from a server, reachable by all clients and execute the script to disable windows updates on a group of windows machines. Though it is written to specifically disable windows update, it can be modified to execute other scripts as well. The playbook configuration file is ass follows, replace enclosed < > tags with the desired values:

---
- hosts: <inventory group / hosts>
  tasks:
  - name: download script to disable windows update
    win_get_url:
      url: http://<url>/disable_windows_update.ps1
      dest: C:\
  - name: execute disable windows update script
    win_shell: C:\disable_windows_update.ps1
  - name: remove script
    win_file:
      path: C:\disable_windows_update.ps1
      state: absent