Tag Archives: linux

Install Ruby 2.6.1 via RVM on CentOS

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Install Prerequisites 

yum install -y curl gcc-c++ patch readline readline-devel zlib zlib-devel libyaml-devel libffi-devel openssl-devel make cmake bzip2 autoconf automake libtool bison libssh2-devel libicu-devel

Install RVM

curl -L get.rvm.io | bash -s stable

Setup RVM, install Ruby 2.6.1 and set to default.

source /etc/profile.d/rvm.sh 
rvm install 2.6.1 
rvm use --default 2.6.1

You may need to add root or the user your using to the rvm group

sudo usermod -G rvm username

Pulled some of the info from here https://github.com/ytti/oxidized#installing-ruby-212-using-rvm

Bash ANSI-C Quoting

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Pulled from https://www.gnu.org/software/bash/manual/bashref.html#ANSI_002dC-Quoting

As a side note there is a lot of good bash info out here. https://www.gnu.org/software/bash/manual/bashref.html

3.1.2.4 ANSI-C Quoting

Words of the form $'string' are treated specially. The word expands to string, with backslash-escaped characters replaced as specified by the ANSI C standard. Backslash escape sequences, if present, are decoded as follows: \a

alert (bell) \b

backspace \e\E

an escape character (not ANSI C) \f

form feed \n

newline \r

carriage return \t

horizontal tab \v

vertical tab \\

backslash \'

single quote \"

double quote \?

question mark \nnn

Some examples

echo Hello $'\t' World

Returns “Hello World” with a tab space between both words.

echo Hello $'\n' World

Returns Hello on one line and World on the second

echo "\"Hello World\""

Returns “Hello World” inside double quotes

Bash script to send messages to Microsoft Teams

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Copy and save into teams.sh file. Make executable. Change web hook, Run!

The script is a modified Slack script from off the web.

#!/bin/bash
# bash script to send messages to Microsoft Teams.
 function usage {
     echo "HELP ME!"
     echo "description: send messages to Microsoft Teams channels"
     echo "special notes: You'll need to change the teamsUrl variable to contain your webhook from Teams."
     echo "usage: ${0} -b \"Message contents\""
     echo "      -m    Message body"
     echo "      -h    This help info"
     exit 1
 }
 while getopts "m:h" opt; do
   case ${opt} in
     m) msgBody="$OPTARG"
     ;;
     h) usage
     ;;
     \?) echo "Invalid option -$OPTARG" >&2
     ;;
   esac
 done
# Add/Change the webhook to one you created in Teams
 teamsUrl="https://teamswebhook"
 if [[ ! "${msgBody}" ]]; then
     echo "You didn't specify a message!"
     usage
 fi
 read -d '' payLoad << EOF
 {
                     "text": "${msgBody}",
 }
EOF
statusCode=$(curl \
--write-out %{http_code} \
--silent \
--output /dev/null \
-X POST \
-H 'Content-type: application/json' \
--data "${payLoad}" ${teamsUrl})
echo ${statusCode}

Bash script to monitor system service

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This bash script runs and checks to see if a service like httpd, or mysql is running and alerts if it is not.

Script Usage

servicemonitor.sh httpd mariadb

Where httpd and mariadb are the services you want to monitor/check.

Setup Script

Create servicemonitor.sh file and paste the following contents in.

#!/bin/bash

timeHour=`date +%H` # date/time just shows the hour
quietHour="02"    # If it is this hour, then exit program, useful if services are expected to go down during a particular time for maintenance
if ( echo ${timeHour} | grep ${quietHour}); then
         echo "Is during quiet time.  Quiting."
         exit
fi

 function ALERT {
 msg="~/teams.sh -b"  # Sends a message to Microsoft Teams channel.  Needs the teams.sh script in the users home directory.
 ${msg} "$1"
 }
 function SERVICECHECK {
 serviceName="${1}"
 if (systemctl status ${serviceName} | grep Active | grep inactive); then
         ALERT "ERROR: $(hostname) - ${serviceName} - ${0} is inactive"
         echo "ERROR: ${serviceName} is inactive!"
 else
         echo "Running!"
 fi
 }
 for i in $@
 do
 echo Checking ${i}
 SERVICECHECK ${i}
 done

Note the teams.sh script that is called is another script that is called that sends an alert to Microsoft Teams. Is not needed for this script to run, but allows for remote alerting.

Save file and make it executable

chmod +x servicemonitor.sh

Add script to crontab (Optional)

crontab -e

The following runs the script every 5 minutes. Can change the 5 to 1 to run every minute. Change httpd and mariadb to the service you want to monitor.

*/5 * * * * /home/UserName/servicemonitor.sh httpd mariadb

Delete anonymous MySQL user

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Log into mysql

mysql -u root -p

List users

select User,Host from mysql.user;

Should return something like the following

MariaDB [mysql]> select User,Host from user;
 +----------+-----------------------+
 | User     | Host                  |
 +----------+-----------------------+
 | root     | 127.0.0.1             |
 | librenms | localhost             |
 |          | localhost.localdomain |
 +----------+-----------------------+
 3 rows in set (0.00 sec)
MariaDB [mysql]>

Delete anonymous user

Note that there are two single quotes ‘ before the @ sign, not a double quote “

drop user ''@'localhost.localdomain';

apt install python-pip, Unable to locate package – Ubuntu

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When trying to install pip on Ubuntu with

sudo apt install python-pip

get the following error

Unable to locate package python-pip

Does the same thing for other basic packages. One of which was nasm “Dependency for Chipsec”

Issue ended up being that the Community-maintaned source was not enabled. Enabled via the Software & Updates. Should be able to search for it and it should come up.

BASH Script to add new SFTP user and setup permissions

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This script adds a new SFTP user with only sftp access.  Refer to this post on setting up a SFTP server.

Download script

wget www.incredigeek.com/home/downloads/scripts/sftpUserAdd.sh

Make executable

chmod +x sftpUserAdd.sh

Run with the new user you want to create.

./sftpUserAdd.sh sftpUsername

You may need to edit the script and modify the location parameters.

#!/bin/bash
# Automatically setup and add SFTP user
# Script creates new user and setups permissions
newUser=$1
sftpDir="/sftp/"
if grep -q ${newUser} /etc/passwd ;then
        echo ${newUser} Already exsists.  Aborting!
        exit 1
else
        mkdir -p ${sftpDir}/${newUser}/files
        useradd -g sftpusers -d ${sftpDir}/${newUser}/files -s /sbin/nologin ${newUser}
        passwd ${newUser}
        chown ${newUser}:sftpusers /sftp/CareMark/files
fi