Tag Archives: linux

Converting a text file from uppercase to lowercase. | converting text files from uppercase to lowercase

I had a bunch of hostnames in a text file, but some were uppercase and some lowercase. This presents problems when searching and automating tasks, so  I wanted a way to convert them all into lowercase as all text should be in Linux.

Here we are using “tr” to completed this task.

 

How to disable root access to RHEL Redhat systems. | disable root access linux

For security reasons, root access to Linux systems should be disabled as  standard theses days. Some distributions still allow it but other have blocked it by default. We should be taking advantage of sudo, which allows you to log in with your standard unprivileged account but execute root commands with the sudo app.

Here are some quick and easy steps to stop root access to your system and improve your security footprint.

This command will lock the root account

This will replace the hashed password with “!”, which is another way to stop logons

To add another level of security you should also disable root logons from the ssh server too. Here is how to do so,

Ensure the following entry is set, if it currently does not exist in the config file, add it anywhere.

 

Syslog permissions blocking Splunk Access | syslog splunk permissions /var/log/messages

Had a problem splunk having access permissions to /var/log/messages, syslog would change the permissions to read only by root and no one else. The fix is in the syslog config file. See below.

Should have an entry like this 

Pay particular attentions to,

Then restart syslog

 

RHEL and Fedora setting password expiry | bash linux password expire chage

A very common Linux administration task is to set user account to expire their password and request a new account password from the user.

To see what the current policy is set to, execute the following.

You should see output like.

You can change the password expiry with the following command

 

Setup a backup job for your LAMP sites. | Setup a backup job for your LAMP sites.

I wrote a script which takes a backup of my webserver, taking a snapshot of all the website content, database, and configuration files.

Theory is if the webserver died, we would be about to result quickly using the data backed up.

On the server, put the following script and below is the cron entry which triggers every week. You will need up change the username and password for your mysql server.

This is the cron entry which fires up every friday.

Now this script will be on a linux machine somewhere else, it will connect and copy the backup archive file generated. You must first setup the ssh key so that its passwordless connection.

Simplicity it key! It works and will get you out of trouble. Well worth the 5minute investment.

 

 

Finding deleted text on a Linux system using Grep | finding deleted text files using grep

I ran across a neat little trick when attempted to recover a deleted file on my Linux box.

You can use grep to search your disk at a bit level for a deleted file, on the condition you know a string in its contents.

You can test it like this, write a text file and store a specific string in it. ie

then insert something like

then delete the file.

Now lets find the deleted file.

Your missing file should appear with a bit of junk above and below the contents of your file.

Increase the lines in the -B10 -A10 depending how big your file it.

 

 

Get an email when your public IP changes | get notified when your public ip changes.

Alot of us have ISPs which change your IP address and you may not want to setup a client with a dynamic IP or want a backup in case the services fails.

So i developed a bash script which checks to see if your public IP has changed. If it has it will log it and email you the new IP.

See below.

 

 

Dump1090 to MySQL Script | send flight data from dump1090 to mysql

I wanted a script which would read all the live dump1090 aircraft data and log it to a mysql database.

This base script does it, it will dump all the data to Mysql every minute.

It will start the dump1090 server and kick off a process which reads/sorts and inserts.

 

Bash script to generate a sitemap.xml on a WordPress instance | bash script to generate a sitemap.xml for wordpress

There are free online tool to generate sitemap.xml, but the one I used would only index 500 pages. My site www.techinterchange.com.au has more, so I decide to write a bash script which ill index the site and generate an sitemap.xml.

Its simple, ill continue to add features and make it more reliable. This is only working with WordPress atm, Ill improve with the next revision.