Archive for the ‘Guides’ Category

Setup Remote Logging on an Ubuntu rsyslog Server for DD-WRT to Use

Wednesday, June 9th, 2021

Setup Remote Logging on an Ubuntu rsyslog Server for DD-WRT to Use

Enable remote logging on an Ubuntu server by configuring rsyslog to allow remote connections from port 514 (adjust as needed):

sudo nano /etc/rsyslog.conf

Uncomment the imudp and imtcp load module statements like so (adjusting as needed):

# provides UDP syslog reception
module(load="imudp")
input(type="imudp" port="514")

# provides TCP syslog reception
module(load="imtcp")
input(type="imtcp" port="514")

Create a logging template and apply it only to remote hosts that start with "c-" (comcast connection remote host prefix [followed by the IP address of the device which can change])

# Comcast remote logging
$template remote-incoming-logs, "/var/log/remote_logs/%HOSTNAME%/%PROGRAMNAME%.$
if $fromhost startswith "c-" then -?remote-incoming-logs

Save and quit.

Restart the rsyslog daemon:

sudo service rsyslog restart

Remote logs will be stored in /var/log/remote_logs

Configure logrotate to process and rotate these logs automatically (so you don't lose them and have a history on them):

sudo nano /etc/logrotate.d/ddwrt

Paste these contents into the file:

/var/log/remote_logs/*.log /var/log/remote_logs/*/*.log {
    daily
    missingok
    compress
    delaycompress
    su syslog adm
}

Save and quit.

Everything has been configured, and remote logging should work from your DD-WRT router once you set the remote URL to your server's IPAddress:port combo and apply the changed settings.

CentOS LVM and Software RAID Partitioning Instructions

Sunday, May 30th, 2021

Installing and Configuring CentOS to Host KVM Virtual Machines

GUI

When configuring a fresh install of CentOS for a KVM host machine (the main server that hosts all of the virtual machines), I like to run a GUI to make managing some of the virtual machines easier.  Thus, during install, choose the options for CentOS with Minimal GUI:

RAID 10 LVM Partitions

When configuring the hard drive partitions, set it up to use RAID 10 LVM SOFTWARE RAID:

Create volume group called "vms" without the quotes that is setup as RAID 10 (set volume group space to be as large as possible).

Set the "/" partition to 100GB XFS LVM (RAID10).

Set the "swap" partition to 32GB.

Only setup those two partitions.  The remaining space in the RAID 10 volume group "vms" will be used for KVM containers (and the remaining space does NOT need to be assigned to any mount points).

That's all.

Increasing KVM Guest Hard Disk (Hard Drive) Space

Sunday, May 30th, 2021

Increasing KVM Guest Hard Disk (Hard Drive) Space

Increasing the hard drive space in a KVM guest can be rather tricky.  The first step is to shutdown (completely turn off) the guest machine by running the below command from the guest system:

sudo shutdown -h now

Once the guest machine has been turned off (verify it is off by using sudo virt-manager on the host machine to see if it's no longer running), on the host machine, resize the LVM partition by running the following command (and adjust the size as necessary):

sudo lvextend -L+78G /dev/vg_vps/utils

If you need help identifying the name of the disk your guest has been assigned, run this command from the host:

sudo virsh domblklist {VIRSH_NAME_OF_VIRTUAL_MACHINE}

For my example, I would use this command:

sudo virsh domblklist utils

From the host machine, download the GParted live ISO image for your system's architecture (x86 or x64).  Start virt-manager:

sudo virt-manager

Assign a CD drive to the virtual machine you're expanding the hard drive space for, and assign / mount the GParted ISO to it.  Change the boot order so that the KVM guest boots from the CD first.  Save your settings and start the KVM guest virtual machine.  Boot into GParted Live.  GParted will run automatically.  Use GParted to expand the partitions so that they make use of the added storage based on your own preferences.  Apply the resize operation.  Exit GParted and shutdown the virtual machine so that it's off again. Remove the CD drive from the boot options from virt-manager, and then start the KVM guest again. 

If Guest Doesn't Use LVM Partitioning

If your KVM guest virtual machine hasn't been configured to use LVM, the added hard drive space should already be available to your system.  Verify it has been expanded by again running the df -h command.  You're done!

If Guest Uses LVM

Let the OS boot.  From the guest, the file system needs to be resized itself.  You can do this by running the following command to see the current space allocated to your system's partitions:

df -h

You'll see a bunch of output similar to:

Filesystem                  Size  Used Avail Use% Mounted on
udev                        2.9G     0  2.9G   0% /dev
tmpfs                       597M  8.3M  589M   2% /run
/dev/mapper/utils--vg-root  127G   24G   98G  20% /
tmpfs                       3.0G     0  3.0G   0% /dev/shm
tmpfs                       5.0M     0  5.0M   0% /run/lock
tmpfs                       3.0G     0  3.0G   0% /sys/fs/cgroup
/dev/vda1                   720M   60M  624M   9% /boot
tmpfs                       597M     0  597M   0% /run/user/1000

You'll notice that the added hard drive space doesn't show up on any of the partitions.  However, it is available to be assigned to these partitions.  To assign additional space, you will need to resize it using these commands (run from the guest virtual machine… the machine you're resizing):

lvextend /dev/mapper/utils--vg-root -L +78G
resize2fs /dev/mapper/utils--vg-root

Obviously, you need to substitute the name of the LVM partition with the one from your system shown in your output of the df -h command.

Resources

https://tldp.org/HOWTO/LVM-HOWTO/extendlv.htmlMirror if Offline

https://sandilands.info/sgordon/increasing-kvm-virtual-machine-disk-using-lvm-ext4Mirror if Offline

Obtaining Let’s Encrypt HTTP Validation IP Addresses

Saturday, July 11th, 2020

Obtaining Let's Encrypt HTTP Validation Server IP Addresses

Use your webserver logs:

sudo apt-get install john
cat access_log.1 | grep "Let's Encrypt" | awk '{print $1}' | unique ips
cat ips

Installing Chrome WebDriver (Linux Script)

Wednesday, August 28th, 2019

Installing Chrome WebDriver (Linux Script)

Find out which version of Chrome is installed on your system before running the below commands.  You can find out your chrome version by running the following command:

google-chrome --version

Adjust the version number (replace {VERSION_NUMBER})  in the below commands to match the version installed on your system!!!

sudo -i
cd ~/Downloads
rm chromedriver_linux64.zip
wget -N https://chromedriver.storage.googleapis.com/{VERSION_NUMBER}/chromedriver_linux64.zip
unzip chromedriver_linux64.zip
mv chromedriver /usr/bin/chromedriver
chown root:root /usr/bin/chromedriver
chmod +x /usr/bin/chromedriver

Selenium and other libraries that rely on the Chrome WebDriver should now work properly.

CentOS – Using NAT with KVM Guests

Wednesday, July 17th, 2019

CentOS – Using NAT with KVM Guests

Please note that all commands in this guide must be run on the main HOST machine (the physical machine).  They should not be run on KVM guests (virtual machines).

If your server has a limited number of IPv4 addresses, it might be best to setup and run some virtual machines that are configured to use the default NAT network interface that KVM provides.  This will allow you to run multiple virtual machines that share the same IP address.  Think of it as setting up a home network with multiple devices with certain ports forwarded to specific devices for incoming connections.

First, create the virtual machines that are going to use NAT using virt-manager as you normally would.  In the virtual machine configuration wizard, assign the default NAT network interface named "virbr0".  After the virtual machines have been created, shut down the virtual machines.  Now, we'll assign these virtual machines static LAN IP addresses so that we can port forward certain ports and always have them reach the proper virtual machines. 

The first thing we need to do is get the MAC address of each virtual machine.  Write down the name of the virtual machine and its MAC address, as we'll need this information later on when we edit the NAT interface and assign static LAN IP addresses to our virtual machines.  Run this command to retrieve the MAC address for a specific virtual machine.

virsh dumpxml VM_NAME | grep -i '<mac'

Using the MAC address information from the VMs we want to use NAT with, edit the default NAT interface by running the below command. 

virsh net-edit default

If for some reason the NAT interface is not named default, you can find it by running the below command:

virsh net-list

After the <range /> entry, assign the static LAN IP addresses similar to the following:

<dhcp>
      <range start='192.168.122.2' end='192.168.122.254'/>
      <host mac='52:54:00:ff:4a:2a' name='vm1' ip='192.168.122.13'/>
      <host mac='52:54:00:bb:35:67' name='vm2' ip='192.168.122.14'/>
      <host mac='52:54:00:aa:d9:f2' name='vm3' ip='192.168.122.15'/>
</dhcp>

Save the file with your desired values and quit the editor.  Restart the NAT interface by running the below commands:

virsh net-destroy default
virsh net-start default

Now, you'll need to setup your iptables port forwarding rules.  Adjust the below rules as necessary (changing the port numbers to the ones you want to use) and then save them so that they persist:

iptables -I FORWARD -o virbr0 -d 192.168.122.13 -j ACCEPT
iptables -t nat -I PREROUTING -p tcp --dport 39989 -j DNAT --to 192.168.122.13:39989
iptables -I FORWARD -o virbr0 -d 192.168.122.14 -j ACCEPT
iptables -t nat -I PREROUTING -p tcp --dport 39990 -j DNAT --to 192.168.122.14:39990
iptables -I FORWARD -o virbr0 -d 192.168.122.15 -j ACCEPT
iptables -t nat -I PREROUTING -p tcp --dport 39991 -j DNAT --to 192.168.122.15:39991
iptables -t nat -A POSTROUTING -s 192.168.122.0/24 -j MASQUERADE
iptables -A FORWARD -o virbr0 -m state --state RELATED,ESTABLISHED -j ACCEPT
iptables -A FORWARD -i virbr0 -o br0 -j ACCEPT
iptables -A FORWARD -i virbr0 -o lo -j ACCEPT
iptables-save
service iptables save

Congrats, your virtual machines are now using NAT, have been assigned static LAN IP addresses, and iptables rules on the host server have been configured to port forward specific ports to each NAT VM.


Persistently Saving NAT Port Forward Rules

The only solution I found that would persistently save my NAT forwarding rules is to create a libvirt hook bash script as mentioned here

service iptables stop
iptables -F
service iptables save
service iptables start
mkdir -p  /etc/libvirt/hooks
nano  /etc/libvirt/hooks/qemu

The contents of the "/etc/libvirt/hooks/qemu" file should look similar to the following:

#!/bin/bash
# IMPORTANT: Change the "VM NAME" string to match your actual VM Name.
# In order to create rules to other VMs, just duplicate the below block and configure
# it accordingly.
if [ "${1}" = "vm1" ]; then   # Update the following variables to fit your setup
   GUEST_IP=192.168.122.13
   GUEST_PORT=39989
   HOST_PORT=39989   
   if [ "${2}" = "stopped" ] || [ "${2}" = "reconnect" ]; then
    /sbin/iptables -D FORWARD -o virbr0 -d  $GUEST_IP -j ACCEPT
    /sbin/iptables -t nat -D PREROUTING -p tcp --dport $HOST_PORT -j DNAT --to $GUEST_IP:$GUEST_PORT
   fi
   if [ "${2}" = "start" ] || [ "${2}" = "reconnect" ]; then
    /sbin/iptables -I FORWARD -o virbr0 -d  $GUEST_IP -j ACCEPT
    /sbin/iptables -t nat -I PREROUTING -p tcp --dport $HOST_PORT -j DNAT --to $GUEST_IP:$GUEST_PORT
   fi
fi
if [ "${1}" = "vm2" ]; then   # Update the following variables to fit your setup
   GUEST_IP=192.168.122.14
   GUEST_PORT=39990
   HOST_PORT=39990   
   if [ "${2}" = "stopped" ] || [ "${2}" = "reconnect" ]; then
        /sbin/iptables -D FORWARD -o virbr0 -d  $GUEST_IP -j ACCEPT
        /sbin/iptables -t nat -D PREROUTING -p tcp --dport $HOST_PORT -j DNAT --to $GUEST_IP:$GUEST_PORT
   fi
   if [ "${2}" = "start" ] || [ "${2}" = "reconnect" ]; then
        /sbin/iptables -I FORWARD -o virbr0 -d  $GUEST_IP -j ACCEPT
        /sbin/iptables -t nat -I PREROUTING -p tcp --dport $HOST_PORT -j DNAT --to $GUEST_IP:$GUEST_PORT
   fi
fi
if [ "${1}" = "vm3" ]; then   # Update the following variables to fit your setup
   GUEST_IP=192.168.122.15
   GUEST_PORT=39991
   HOST_PORT=39991
   if [ "${2}" = "stopped" ] || [ "${2}" = "reconnect" ]; then
        /sbin/iptables -D FORWARD -o virbr0 -d  $GUEST_IP -j ACCEPT
        /sbin/iptables -t nat -D PREROUTING -p tcp --dport $HOST_PORT -j DNAT --to $GUEST_IP:$GUEST_PORT
   fi
   if [ "${2}" = "start" ] || [ "${2}" = "reconnect" ]; then
        /sbin/iptables -I FORWARD -o virbr0 -d  $GUEST_IP -j ACCEPT
        /sbin/iptables -t nat -I PREROUTING -p tcp --dport $HOST_PORT -j DNAT --to $GUEST_IP:$GUEST_PORT
   fi
fi

Save and exit.  Make the script executable.

chmod +x /etc/libvirt/hooks/qemu

If you're attempting to forward incoming traffic (only traffic originating from the outside), be sure to exclude the main virbr0 interface so that requests originating from the DHCP LAN aren't forwarded to itself.  This is helpful for port forwarding DNS (port 53).  Incoming requests from outside of the network will be forwarded to the specified server, but outgoing DNS requests made from the server will NOT be forwarded back to itself.  Basically, you want to forward all traffic on port 53 to that specific server except for traffic that originates from that server.  So, be sure to add this line if that is the case:

/sbin/iptables -t nat -I PREROUTING \! -i virbr0 -p udp --dport 53 -j DNAT --to $GUEST_IP:$GUEST_PORT

More information can be found here:  https://serverfault.com/questions/1042383/kvm-port-forwarding-port-53-to-guest-via-nat-temporary-failure-in-name-resolut/1042394#1042394

Reboot the host server.


Old Instructions for Persistent Saving (Non-Working)

If your iptables forwarding rules are not persisted after the host machine is rebooted or shutdown, run the following commands:

sudo -i
yum install -y iptables-services
systemctl stop firewalld
systemctl disable firewalld
systemctl enable iptables
nano /etc/sysconfig/iptables-config 

Change the below values to "yes":

IPTABLES_SAVE_ON_RESTART="yes"
IPTABLES_SAVE_ON_STOP="yes"

Save and exit.  Reboot the server.

If you're still having issues, try this (will clear your existing iptables rules):

iptables-save > iptables_bk
service iptables stop
iptables -F
<run iptables NAT rules here>
<run any other iptables rules you want>
service iptables save
service iptables start

More Detailed Guide

Obtaining Let’s Encrypt HTTPS SSL Certificate on Windows

Friday, May 10th, 2019

Obtaining Let's Encrypt HTTPS SSL Certificate on Windows

Install the .NET Framework version 4.7.2, and then:

Download ACME Windows Client – WACS

To obtain a certificate, run the WACS.exe with the following arguments:

wacs.exe --target manual --host {DOMAIN_NAME} --webroot {PATH_TO_DOMAIN_ROOT_LIKE_C:\zpanel\panel} --emailaddress {EMAIL_ADDR} --accepttos --validation filesystem --store pemfiles --pemfilespath C:\certs

 

Installing the Newest Version of Python 2.7.x on Older Versions of Ubuntu (like 14.04 and 16.04)

Thursday, May 9th, 2019

Installing the Newest Version of Python 2.7.x on Older Ubuntu Systems

If you need to upgrade to the newest version of Python 2.7.x, and you're running an older distribution (like Ubuntu 14.04), use the following commands to get and compile the latest version from source (works on Ubuntu 17.04 and older – tested on Ubuntu 14.04):

sudo apt-get install build-essential checkinstall
sudo apt-get install libreadline-gplv2-dev libncursesw5-dev libssl-dev libsqlite3-dev tk-dev libgdbm-dev libc6-dev libbz2-dev
version=2.7.18
cd ~/Downloads/
wget https://www.python.org/ftp/python/$version/Python-$version.tgz
tar -xvf Python-$version.tgz
cd Python-$version
./configure --with-ensurepip=install
make
sudo make install

Install requests and hashlib:

sudo rm /usr/lib/python2.7/dist-packages/chardet*.egg-info
sudo rm -r /usr/lib/python2.7/dist-packages/chardet
sudo rm /usr/lib/python2.7/lib-dynload/_hashlib.x86_64-linux-gnu.so
sudo rm /usr/lib/python2.7/lib-dynload/_hashlib.i386-linux-gnu.so
sudo pip install requests
sudo easy_install hashlib

You may need to create a symlink for chardet after installing it directly from pip:

ln -sf /usr/local/lib/python2.7/site-packages/chardet /usr/lib/python2.7/dist-packages/chardet

If you get the error of "ImportError: cannot import name _remove_dead_weakref" when running a pam python based authentication script after installing the new version of python, try this fix:

sudo cp /usr/local/lib/python2.7/weakref.py /usr/local/lib/python2.7/weakref_old.py
sudo cp /usr/lib/python2.7/weakref.py /usr/local/lib/python2.7/weakref.py

Getting Let's Encrypt Certbot to Work:

Now, you'll need to delete the EFF directory from the /opt directory to avoid old configuration issues that were used for your older version of python.  Once you cleanup this directory, you'll run certbot again so it can reconfigure itself. 

sudo rm -r /opt/eff.org/
sudo certbot

Old Way

jonathonf is now a very greedy person and has made his repositories private, so this method no longer works as of 12/20/2019.

sudo add-apt-repository ppa:jonathonf/python-2.7
sudo apt-get update
sudo apt-get install python2.7

Then, you'll need to cleanup a few leftover system packages manually before installing the newest version of python-pip.  If you don't do this, you'll run into problems installing some new packages using pip.

sudo rm /usr/lib/python2.7/dist-packages/chardet*.egg-info
sudo rm -r /usr/lib/python2.7/dist-packages/chardet
sudo rm /usr/lib/python2.7/lib-dynload/_hashlib.x86_64-linux-gnu.so
sudo rm /usr/lib/python2.7/lib-dynload/_hashlib.i386-linux-gnu.so

Now, you can download and install the newest version of python-pip:

curl https://bootstrap.pypa.io/get-pip.py -o get-pip.py
sudo python get-pip.py

Getting Let's Encrypt Certbot to Work:

First, you'll need to install a few packages that Certbot (the Let's Encrypt client) uses:

sudo pip install requests
sudo pip install hmac

Now, you'll need to delete the EFF directory from the /opt directory to avoid old configuration issues that were used for your older version of python.  Once you cleanup this directory, you'll run certbot again so it can reconfigure itself. 

sudo rm -r /opt/eff.org/
sudo certbot

You're done.

Full list of commands (for quickly doing all of the above):

sudo -i
add-apt-repository ppa:jonathonf/python-2.7
apt-get update
apt-get install python2.7
rm /usr/lib/python2.7/dist-packages/chardet*.egg-info
rm -r /usr/lib/python2.7/dist-packages/chardet
rm /usr/lib/python2.7/lib-dynload/_hashlib.x86_64-linux-gnu.so
rm /usr/lib/python2.7/lib-dynload/_hashlib.i386-linux-gnu.so
mkdir -p /root/Downloads
cd /root/Downloads
curl https://bootstrap.pypa.io/get-pip.py -o get-pip.py
python get-pip.py
pip install requests
pip install hmac
rm -r /opt/eff.org/
certbot

Change the Default Editor to nano in Linux

Saturday, April 27th, 2019

Use nano as the Default Editor

If you hate vi like I do, you can configure Linux to always default to using the nano editor.

Simply add the following to the bottom of the /etc/bashrc file:

export EDITOR="nano"

Save the file.  nano is now the default editor.  When you use

sudo crontab -e

The nano editor will now be used by default.

Configuring Let’s Encrypt Certbot on CentOS 7 with lighttpd

Saturday, April 27th, 2019

Configuring Let's Encrypt Certbot on CentOS 7 with lighttpd

Installing Certbot

First, install certbot by using the below commands:

sudo yum -y install epel-release
sudo yum install certbot

certbot is python based program that allows you to request SSL certificates for your domains. 

Request a Certificate

Use the below command to request a certificate (adjust paths and replace the test.com domain as necessary):

sudo certbot certonly --webroot -w /var/www/vhosts/test/httpdocs -d test.com

A certificate has now been stored in /etc/letsencrypt/live.  Create a combined certificate format by using the below command (replacing test.com with your real domain):

/bin/cat /etc/letsencrypt/live/test.com/cert.pem /etc/letsencrypt/live/test.com/privkey.pem > /etc/letsencrypt/live/test.com/custom.pem && /bin/chmod 777 /etc/letsencrypt/live/test.com/custom.pem && /sbin/service lighttpd restart

Certificate Renewal Cronjobs

You may want to create a cronjob to renew the certificate and a cronjob for regenerating the combined format certificate since the underlying certificate file can change (such as when it's renewed):

sudo crontab -e

Insert the below cronjobs:

0 1 * * 1 /usr/bin/certbot renew --quiet
5 1 * * 1 /bin/cat /etc/letsencrypt/live/test.com/cert.pem /etc/letsencrypt/live/test.com/privkey.pem > /etc/letsencrypt/live/test.com/custom.pem && /bin/chmod 777 /etc/letsencrypt/live/test.com/custom.pem && /sbin/service lighttpd restart

Save your crontab configuration. 

Setting Up Lighttpd to Use SSL Certificate

Edit your default-enabled lighttpd configuration file in /etc/lighttpd/vhosts.d to look similar to the following (replacing test.com with your real domain and adjusting various file paths)

$HTTP["host"] == "test.com" {
  var.server_name = "test.com"
  server.name = server_name  server.document-root = vhosts_dir + "/test/httpdocs"
  #accesslog.filename          = vhosts_dir + "/test/log" + "/access.log"
}
$SERVER["socket"] == ":80" {
  server.document-root = vhosts_dir + "/test/httpdocs"
}
$SERVER["socket"] == ":443" {
    ssl.engine           = "enable"
    ssl.pemfile          = "/etc/letsencrypt/live/test.com/custom.pem"
    server.document-root = vhosts_dir + "/test/httpdocs"
    ssl.ca-file = "/etc/letsencrypt/live/test.com/chain.pem" # Root CA
    server.name = "test.com" # Domain Name OR Virtual Host Name
}

Here's how you can set a different document root for specific https (port 443) virtual hosts:

$SERVER["socket"] == ":443" {
    ssl.engine           = "enable"
    ssl.pemfile          = "/etc/letsencrypt/live/test.com/custom.pem"
    server.document-root = vhosts_dir + "/test/httpdocs/"
    ssl.ca-file = "/etc/letsencrypt/live/test.com/chain.pem" # Root CA
    server.name = "test.com" # Domain Name OR Virtual Host Name
    
    $HTTP["host"] =~ "(^|www\.)somethingelse.test.com" {
        server.document-root = vhosts_dir + "/test/httpdocs/subdir"
    }
}

Save and restart the lighttpd service.

sudo service lighttpd restart

Congrats, SSL is now available on your domain, and your Let's Encrypt certificate has been configured and will be renewed automatically by your cronjob.