Install SSH Server on Linux (Debian, Ubuntu, Fedora, CentOS, RedHat)

Debian / Ubuntu

sudo apt-get install -y openssh-server

RPM based Distros, Fedora / CentOS / RedHat

sudo dnf install -y openssh-server

or use yum

sudo yum install -y openssh-server

Start ssh service

sudo systemctl start sshd

By default the SSH service should start when the system starts, but if not try the following command to enable the service on boot up.

Debian / Ubuntu

systemctl enable ssh

Fedora, CentOS, RedHat

systemctl enable ssh

Change SSH port

Not necessary, but it is a good idea to change the default ssh port.  To change the port edit the sshd file.

vi /etc/ssh/sshd_config

Moving emails to new host with imapsync

More info about imapsync here

Install imapsync

CentOS 7, Works on cPanel servers too

yum install epel-release && yum install imapsync

Once installed check and make sure it works.

imapsync --version

If it gives you the version number you should be good to go.

Move email account

imapsync --host1 mail.emaildomain.com --user1 username@emaildomain.com --password1  "password1" --host2 mail.exampledomain.com --user2 username@movetodomain.com --password2  "password2"

Example :

imapsync --host1 mail.myemail.com --user1 bob@myemail.com --password1  "password1" --host2 mail.incredigeek.com --user2 bob@incredigeek.com --password2  "password2"

Moving Multiple accounts

Best way to move multiple accounts is to use a script and and a list that contains all the usernames and passwords to the accounts you want to move.

example scripts can be found on the imapsync website here is a script example and here is the example file.txt

Example script.

#!/bin/sh
#
# $Id: sync_loop_unix.sh,v 1.6 2015/11/04 18:23:04 gilles Exp gilles $

# Example for imapsync massive migration on Unix systems.
# See also http://imapsync.lamiral.info/FAQ.d/FAQ.Massive.txt
#
# Data is supposed to be in file.txt in the following format:
# host001_1;user001_1;password001_1;host001_2;user001_2;password001_2;
# ...
# Separator is character semi-colon ";" it can be changed by any character changing IFS=';' 
# in the while loop below.
# # Each line contains 6 columns, columns are parameter values for 
# --host1 --user1 --password1 --host2 --user2 --password2
# and a trailing empty fake column to avaid CR LF part going 
# in the 6th parameter password2. Don't forget the last semicolon.
#
# You can add extra options after the variable "$@" 
# Use character backslash \ at the end of each suplementary line, except for the last one.
# You can also pass extra options via the parameters of this script since
# they will be in "$@"

# The credentials filename "file.txt" used for the loop can be renamed 
# by changing "file.txt" below.


echo Looping on account credentials found in file.txt
echo

{ while IFS=';' read  h1 u1 p1 h2 u2 p2 fake
    do 
        { echo "$h1" | egrep "^#" ; } > /dev/null && continue # this skip commented lines in file.txt
        echo "==== Starting imapsync from host1 $h1 user1 $u1 to host2 $h2 user2 $u2 ===="
        imapsync --host1 "$h1" --user1 "$u1" --password1 "$p1" \
                 --host2 "$h2" --user2 "$u2" --password2 "$p2" \
                 "$@"  
        echo "==== Ended imapsync from host1 $h1 user1 $u1 to host2 $h2 user2 $u2 ===="
        echo
    done 
} < file.txt

Example list of accounts to

mail.maildomain.com;user1@incredigeek.com;password1;mail.incredigeek.com;user2@incredigeek.com;password2;

 

How to use,

You can run these command from a Linux computer

Download script

wget www.incredigeek.com/home/downloads/imapsync/imapsync_loop.sh

Make the script executable

chmod +x imapsync_loop.sh

Create a text file named “imapsync_list.txt”

This file will contain the mail server to transfer from, username, and password, and then the mail server to transfer to, username and password.  Add one line per account.

Example:

mail.servertotransferfrom.com;Username1;Password1;mail.servertomoveto.com;Username2;Password2;
mail.servertotransferfrom.com;testuser;123456;mail.servertomoveto.com;bob;123456;

Execute the script to start moving mail

./imapsync_loop.sh

Troubleshooting

In the username you may need to use the username@domainname.tld, so if the username is bob, and the mail domain is incredigeek.com, use bob@incredigeek.com for the username in the imapsync_list.txt.

Setting up SNMP V3 on CentOS

Install SNMP.

yum install net-snmp net-snmp-utils

Configure the SNMP V3 user by running the following command and then following the prompts it gives you.

net-snmp-create-v3-user

Example: The username is “snmpadmin” and the password is”r123456″

[root@localhost ~]# net-snmp-create-v3-user
Enter a SNMPv3 user name to create:
snmpadmin
Enter authentication pass-phrase:
r123456
Enter encryption pass-phrase:
  [press return to reuse the authentication pass-phrase]

adding the following line to /var/lib/net-snmp/snmpd.conf:
   createUser snmpadmin MD5 "r123456" DES
adding the following line to /etc/snmp/snmpd.conf:
   rwuser snmpadmin
[root@localhost ~]#

 

Start snmpd service

service snmpd start

configure snmp to start on system boot.

chkconfig snmpd on

 

Test and make sure snmp is working

replace “password” and “username” with the ones you setup when you created the SNMP V3 user.

snmpwalk -v 3 -a MD5 -A password -l authNoPriv -u username localhost

If you receive something like “snmpwalk: Timeout” then something is not working correctly.  Check to make sure the service is started, and make sure that your firewall is not blocking SNMP.

If you are running a firewall, run the following commands to allow it through.

firewall-cmd --zone=public --add-port=161/udp --permanent
semanage port -a -t snmp_port_t -p udp 161
firewall-cmd --reload

On iptables you should be able to do

 iptables -A INPUT -p tcp -m state --state NEW -m tcp --dport 161 -j ACCEPT

or add it to /etc/sysconfig/iptables and then restart iptables

Set up Minecraft Server on CentOS 6

Update system

yum update -y

Install Java and wget

yum install -y java wget

Allow Minecraft port through the firewall

Insert the following line in your iptables config file, found in “/etc/sysconfig/iptables”

-A INPUT -m state --state NEW -m tcp -p tcp --dport 25565 -j ACCEPT

Example:

vi /etc/sysconfig/iptables
# Firewall configuration written by system-config-firewall
 # Manual customization of this file is not recommended.
 *filter
 :INPUT ACCEPT [0:0]
 :FORWARD ACCEPT [0:0]
 :OUTPUT ACCEPT [0:0]
 -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
 -A INPUT -p icmp -j ACCEPT
 -A INPUT -i lo -j ACCEPT
 -A INPUT -m state --state NEW -m tcp -p tcp --dport 22 -j ACCEPT
 -A INPUT -m state --state NEW -m tcp -p tcp --dport 25565 -j ACCEPT <--- Added Rule
 -A INPUT -j REJECT --reject-with icmp-host-prohibited
 -A FORWARD -j REJECT --reject-with icmp-host-prohibited
 COMMIT
 ~
 ~
 :wq
"/etc/sysconfig/iptables" 14L, 544C written
 [root@localhost ~]# service iptables restart
 iptables: Setting chains to policy ACCEPT: filter [ OK ]
 iptables: Flushing firewall rules: [ OK ]
 iptables: Unloading modules: [ OK ]
 iptables: Applying firewall rules: [ OK ]
 [root@localhost ~]#

 

Setup your network.

you will need to edit the network config file in “/etc/sysconfig/network-scripts/ifcfg-eth0”

DHCP

If your using DHCP then just change “ONBOOT=no” to “ONBOOT=yes”

Static

If you need a static address, then change “ONBOOT=no” to “ONBOOT=yes” and change “BOOTPROTO=dhcp” to “BOOTPROTO=static”

add the following to “/etc/sysconfig/network-scripts/ifcfg-eth0”

IPADDR=192.168.1.100
NETMASK=255.255.255.0
GATEWAY=192.168.1.1
BROADCAST=192.168.1.255
DNS1=1.1.1.1

 

Start Minecraft server on system boot

Create user

useradd -m steve

Create password for steve

passwd steve

Login as your new user.

su steve

Go to user root directory

cd ~/

Download the minecraft server jar

wget https://s3.amazonaws.com/Minecraft.Download/versions/1.8.7/minecraft_server.1.8.7.jar

Create a directory for the start up script and create start up script.

mkdir /home/steve/mc
touch /home/steve/mc/mcstart.sh

Copy and paste the following text into mcstart.sh

#! /bin/sh
# /etc/init.d/mcserver

### BEGIN INIT INFO
# Minecraft CraftBukkit Start script
### END INIT INFO

case "$1" in
  start)
    echo "Starting mcserver"
    MCDIR="/home/steve/"
    cd "$MCDIR"
    java -Xmx512M -jar minecraft_server.1.8.7.jar -o true &
;;
  stop)
    echo "Stopping mcserver"
    kill `pgrep mcserver`
    ;;
  *)
    echo "Usage: /etc/init.d/mcserver {start|stop}"
    exit 1
    ;;
esac
exit 0

Make the script executable

chmod +x /home/steve/mc/mcstart.sh

Add mcstart.sh to the crontab

Access the crontab by running the following command

crontab -e

Add the following to the crontab.

@reboot /home/steve/mc/mcstart.sh start

Start the server.

/home/steve/mc/mcstart.sh start

Note: Starting the server will fail because you need to agree to the end user license agreement.

Agree to the eula

sed -i s/false/true/g eula.txt

Reboot the server and connect to your new Minecraft server.

How To change the Hostname in CentOS 7

Check current hostname with the hostname command.

hostname

Change hostname with hostnamectl

hostnamectl set-hostname newhostname

 

Example:

Changing hostname from “localhost” to “newhost”.

[root@localhost ~]# hostname
localhost
[root@localhost ~]# hostnamectl set-hostname newhost
[root@localhost ~]# hostname
newhost
[root@localhost ~]# 

 

 

How to Install Zenoss 5 on CentOS 7

Note:

  1. This is not a comprehensive guide, if you need more info, refer to the installation manual here.
  2. This assumes that all your partitions are going to be on one drive

Installing CentOS 7

Note: If you have issues installing CentOS via the default install interface, try using the Fallback graphics mode, found in the Grub boot menu under “trubbleshooting”.

Install CentOS like you normally would, just be sure to leave at least 60GB of free space for Docker/Zenoss

2

You can Select Automatic Partitioning, but you will need to make additional space available.  I just configured it manually.3

 Note that I have about 75GB of free space, this will be used for “/var/lib/docker” and “/opt/serviced/var/volumes”.  We’ll set these up later on.1

You don’t necessarily need to setup a user, but you can if you want to.  4

Once your finished reboot and login.5

 

Configuring CentOS for Zenoss

Setup network

You will need to setup your network settings.  Refer to this post to set a static IP address if needed.

 

Note: In CentOS 7 ifconfig is not installed by default.  If you need to check the IP address use the following command.

ip addr sh

After your connected to the internet you can install ifconfig with

yum install -y net-tools

Setup Hostname

Zenoss seems to have issues if you change the hostname after it is installed so be sure to set up the hostname before you start installing zenoss.

Check current hostname

hostname

Change the hostname.  Replace “newhostname” with your new hostname.

hostnamectl set-hostname newhostname

After you finish configuring the hostname, add it to “/etc/hosts” with the following command.  Change the IP address and the hostname “zenoss” to your systems IP address and hostname.

echo "192.168.56.101   zenoss" >> /etc/hosts

Update your system

yum update -y

Disable Firewall

systemctl stop firewalld && systemctl disable firewalld

Enable persistent log storage

mkdir -p /var/log/journal && systemctl restart systemd-journald

Create two Btrfs file systems

First create two normal linux partitions using your favorite disk utility.  I am using cfdisk.  Each partition should be over 30GB.

cfdisk /dev/sda

6

Create two Primary partitions and put them at the end and then write and exit.

7

Take note of the two new partitions names.  Mine are “sda4” and “sda3”.

After the above changes are made, it would be a good idea to reboot the machine so the partition table can be updated.

reboot

Now we will reformat the two partitions as Btrfs

Create mount point.

mkdir -p /var/lib/docker /opt/serviced/var/volumes

Change “/dev/sda3” and “/dev/sda4” to your partitions names if they are different.

DOCKER_PART=/dev/sda3
APP_PART=/dev/sda4
mkfs -t btrfs --nodiscard $DOCKER_PART
mkfs -t btrfs --nodiscard $APP_PART

Add the new file systems to fstab, so they automatically mount on boot.

APP_PATH="/opt/serviced/var/volumes"
echo "$DOCKER_PART /var/lib/docker btrfs rw,noatime,nodatacow 0 0" >> /etc/fstab
echo "$APP_PART $APP_PATH btrfs rw,noatime,nodatacow 0 0" >> /etc/fstab

Mount the new filesystems, and make sure that they mounted

mount -a
if [[ `mount | egrep 'docker|serviced'` ]]; then echo "Mounted" ; else echo "Not Mounted" ; fi

You can manually check by running the following command.

mount | egrep 'docker|serviced'

you should receive something like the following

/dev/sda3 on /var/lib/docker type btrfs (rw,noatime,seclabel,nodatasum,nodatacow,space_cache)
/dev/sda4 on /opt/serviced/var/volumes type btrfs (rw,noatime,seclabel,nodatasum,nodatacow,space_cache)

Disable SELinux

By default SELinux is installed and enabled.  To disable SELinux either edit the config file “/etc/selinux/config” and change “SELINUX=enforcing” to “SELINUX=disabled”, or you can run the following command.

EXT=$(date +"%j-%H%M%S")
sudo sed -i.${EXT} -e 's/^SELINUX=.*/SELINUX=disabled/g' \
/etc/selinux/config && \
grep '^SELINUX=' /etc/selinux/config

Enable Dnsmasq

systemctl enable dnsmasq && systemctl start dnsmasq

Install and Configure NTP

yum install -y ntp && systemctl enable ntpd

Have NTP start on system boot and then start NTP

echo "systemctl start ntpd" >> /etc/rc.d/rc.local
chmod +x /etc/rc.d/rc.local
systemctl start ntpd

Download and install the Zenoss repository

rpm -ivh http://get.zenoss.io/yum/zenoss-repo-1-1.x86_64.rpm
yum clean all

Final Reboot

reboot

 

Installing Zenoss

 

Once your logged back into the system start installing zenoss

Install the Zenoss-core service and start docker

yum --enablerepo=zenoss-stable install -y zenoss-core-service
systemctl start docker

Add the Btrfs and DNS flags to the Docker startup options

Identify ip for docker

ip addr | grep -A 2 'docker0:' | grep inet

Add the docker startup options.  Change the ip address if needed.  It should match the one from the previous command.

echo 'DOCKER_OPTS="-s btrfs --dns=172.17.42.1"' >> /etc/sysconfig/docker

Change the volume type for application data

You can manually edit the serviced file “/etc/default/serviced” and change the variable “SERVICED_FS_TYPE” from “rsync” to “btrfs” or run the following command.

EXT=$(date +"%j-%H%M%S")
 sudo sed -i.${EXT} \
 -e 's|^#[^S]*\(SERVICED_FS_TYPE=\).*$|\1btrfs|' \
 /etc/default/serviced

Restart docker

systemctl stop docker && systemctl start docker

Start the control center

systemctl start serviced

you can monitor the process with

journalctl -u serviced -f

Serviced has about 5-10 minutes worth of work to do before you’ll be able to login to the Control Center interface.  If the service fails to start, reboot the server.

Setting up name resolution

To setup name resolution on you local computer just add the following line to your “hosts” file.  On Linux and OS X this is located in “/etc/hosts” On Windows machines it is under “\Windows\Sytem32\Drivers\etc\hosts”

192.168.56.101 hostname zenoss5.hostname hbase.hostname opentsdb.hostname rabbitmq.hostname

Be sure to change the IP address and “hostname”  to the IP address and hostname of your server.  You also might need administrative privileges to edit the hosts file.

10

Logging into the Control Center.

Now open up a web browser and go the following URL.  Change the IP address to your servers IP.

https://192.168.56.101

Login with the Zenoss server root username and password.  If you want to setup a user other then root, please refer to the Zenoss Installation guide here.

11

Change the hostname to your Zenoss server hostname12

Select the check boxes in the next two steps.13 14

Give it a deployment id and deploy it.15 16

Once it is deployed Make sure that it is started.  Once it finishes go log into Zenoss.  It can take awhile for Zenoss to start up, depending on your hardware, so be patient.

The Direct URL for Zenoss is

https://zenoss5.hostname

 

 

How to Install Nagios 4.0.8 on CentOS 6.5

Install the prerequisite packages

yum install gd gd-devel httpd php gcc glibc glibc-common make perl wget

If you want to monitor SNMP you should install net-snmp now

yum install net-snmp net-snmp-utils
service snmpd start
chkconfig snmpd on

Create the Nagios user.

useradd -m nagios
passwd nagios
groupadd nagcmd
usermod -a -G nagcmd nagios
usermod -a -G nagcmd apache

Create a directory to download and build Nagios from

mkdir /root/nagios
cd /root/nagios

Download Nagios and the Nagios plugins

wget http://sourceforge.net/projects/nagios/files/nagios-4.x/nagios-4.0.8/nagios-4.0.8.tar.gz
wget nagios-plugins.org/download/nagios-plugins-2.0.3.tar.gz 

Extract the Nagios zip

tar xvzf nagios-4.0.8.tar.gz
cd nagios-4.0.8

Compile and make it

./configure
make all
make install
make install-init
make install-commandmode
make install-config
make install-webconf

Create a password so you can login to the web interface

htpasswd -c /usr/local/nagios/etc/htpasswd.users nagiosadmin

Enable Nagios on startup

 chkconfig nagios on

Start the service

service nagios start

Install the plugins.

cd ..
tar xvzf nagios-plugins-2.0.2.tar.gz
cd nagios-plugins-2.0.2
./configure
make
make install

Start apache and make sure it starts on boot.

service httpd start
chkconfig httpd on

You should now be able to access Nagios by going to https://nagiosserverip/nagios

If you run into issues check your firewall and make sure SELinux is disabled.

How To Install Zenoss 4.2.5 on CentOS 6.5

First you need to remove mysql-libs

yum remove mysql-libs

Install wget

yum install -y wget

Download the Zenoss install script archive

wget https://github.com/zenoss/core-autodeploy/tarball/4.2.5 -O auto.tar.gz

Extract the archive

tar zxvf auto.tar.gz

and execute the install script

cd zenoss-core-autodeploy-*
./core-autodeploy.sh

Follow the prompts and when it’s finished navigate to http://yourserverip:8080 to complete the install.

How to set a static ip address on CentOS, Fedora, or Red Hat Linux

Open up the following file with your favorite text editor. Change eth0 to the interface you need, like “wlan0” or “eth1”.

 vi /etc/sysconfig/network-scripts/ifcfg-eth0

The file should look something like the following.

DEVICE=eth0
HWADDR=0A:2G:F3:56:66:4B
TYPE=Ethernet
UUID=aeh9421c-6a62-712c-886d-347813g8d1dh
ONBOOT=no
NM_CONTROLLED=yes
BOOTPROTO=dhcp

To set the static IP address change “BOOTPROTO=dhcp” to “BOOTPROTO=static” and add the following to the end of the file. If you want/need the interface to come up when the computer boots up then be sure to change “ONBOOT=no” to “ONBOOT=yes”.

BROADCAST=192.168.1.255
DNS1=8.8.8.8
GATEWAY=192.168.1.1
IPADDR=192.168.1.110
NETMASK=255.255.255.0

So your file should now look like this.

DEVICE=eth0
HWADDR=0A:2G:F3:56:66:4B
TYPE=Ethernet
UUID=aeh9421c-6a62-712c-886d-347813g8d1dh
ONBOOT=yes
NM_CONTROLLED=yes
BOOTPROTO=static
BROADCAST=192.168.1.255
DNS1=8.8.8.8
GATEWAY=192.168.1.1
IPADDR=192.168.1.110
NETMASK=255.255.255.0

Save the file and restart networking.

service network restart

Finally, check you IP address with ifconfig.

root@localhost ~]# ifconfig eth0
eth0      Link encap:Ethernet  HWaddr 0A:2G:F3:56:66:4B  
          inet addr:192.168.1.110  Bcast:192.168.1.255  Mask:255.255.255.0