| by Scott Kilroy

How to check who’s logged in to your linux machine

If you have a linux server, It is absolutely necessary to know how to check the users that are logged in to your system and what they are doing. To do that, you have to get yourself familiar with number of different linux commands. In this guide, we will show you how to identify the […]

The post How to check who’s logged in to your linux machine appeared first on The Linux Juggernaut.

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| by Scott Kilroy

Encrypting directories with eCryptfs in linux

eCryptfs is a POSIX-compliant enterprise-class stacked cryptographic filesystem for Linux. It is derived from Erez Zadok’s Cryptfs, implemented through the FiST framework for generating stacked filesystems. eCryptfs extends Cryptfs to provide advanced key management and policy features. eCryptfs is already included in the official Ubuntu repositories and encrypting directories is a simple matter of mounting […]

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| by Scott Kilroy

Encrypting files in linux

You may work for a super-secret government agency, or you may be just a regular citizen. Either way, you still have sensitive data in your linux system that you need to protect from prying eyes. For that, we can use GNU Privacy Guard to encrypt or cryptographically sign files or messages in our linux machine. […]

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| by Scott Kilroy

Create Snapshot backups using Timeshift in linux

Timeshift is a linux application that we can use to create snapshots in our linux system,. If something bad happens to our linux system (For an example, all the system files and settings are deleted after cyber attack) we can use the snapshot that we create using timeshift to restore the system back and undo […]

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| by Scott Kilroy

Auditing network services with netstat in linux

The following are two reasons why you would want to keep track of what network services are running on your system: To ensure that no legitimate network services that you don’t need are running To ensure that you don’t have any malware that’s listening for network connections from its master You can use the following […]

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| by Scott Kilroy

Web server scanning with Nikto in Linux

Nikto is a special-purpose tool with only one purpose; that is, it’s meant to scan web servers, and only web servers. It’s easy to install, easy to use, and capable of doing a comprehensive scan of a web server fairly quickly. Nikto is built on LibWhisker2 (by RFP) and can run on any platform which […]

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| by Scott Kilroy

Linux log review with logwatch

You know how important it is to do a daily log review. But you also know how much of a drag it is, and that you’d rather take a severe beating. Fortunately, there are various utilities that can make the job easier. Of the various choices in the normal Linux distro repositories, Logwatch is a […]

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| by Scott Kilroy

Collect logs with journald in linux

You’ll find the journald logging system on any Linux distro that uses the systemd ecosystem. Instead of sending its messages to text files, journald sends messages to binary files. Instead of using normal Linux text file utilities to extract information, you have to use the journalctl utility. #journalctl To view the journald log file in […]

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| by Scott Kilroy

Security Auditing for linux with Auditd

So, you have a directory full of super-secret files that only a very few people need to see, and you want to know when unauthorized people try to see them. Or, maybe you want to see when a certain file gets changed, or you want to see when people log into the system and what […]

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| by Scott Kilroy

Scanning for Rootkits with Rootkit Hunter

Rootkits are exceedingly nasty pieces of malware that can definitely ruin your day. They can listen for commands from their masters, steal sensitive data and send it to their masters, or provide an easy-access back door for their masters. They’re designed to be stealthy, with the ability to hide themselves from plain view Install Rootkit […]

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| by Scott Kilroy

Securing Linux System With Maldet

Viruses are a real problem for computers that run the Windows operating system. But, as far as anyone has been able to tell, there’s no such thing as a virus that can harm a Linux-based operating system. So, the only real reason to run an antivirus solution on a Linux machine is to prevent infecting […]

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| by Scott Kilroy

Application Sandboxing with Firejail in Linux

If you have an untrusted application that needs to be run in your Linux system, you can use a sandbox to run the application in a limited environment. In this way you can use the untrusted application without worrying about the security of your system. Sandboxing with Firejail uses namespaces, SECCOMP, and kernel capabilities to […]

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| by Scott Kilroy

Enforcing Strong Password Criteria Using PWQUALITY

Cyber-attacks are becoming increasingly ubiquitous and difficult to deal with and Hackers relentlessly try to exploit common weak passwords. As a result, organizations have to safeguard themselves by using strong password criteria to secure their systems. In this article, we’ll take a look at the mechanics of enforcing strong password criteria on a Linux system. […]

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| by Scott Kilroy

Advanced tips and tricks for using sudo

Now that we’ve looked at the basics of setting up a good sudo configuration in this article, we’re confronted with a bit of a paradox. That is, even though sudo is a security tool, certain things that you can do with it can make your system even more insecure than it was. Let’s see how […]

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| by Scott Kilroy

700,000 WordPress Sites Affected By Zero-day Vulnerability in File Manager Plugin

Yesterday a zero-day vulnerability was discovered in a popular WordPress plugin, File Manager. The vulnerability allows arbitrary file upload and remote code execution. File Manager plugin is a useful plugin that allows users to browse site files in an easy way. The plugin has over 700,000 active installations that make…

The post 700,000 WordPress Sites Affected By Zero-day Vulnerability in File Manager Plugin appeared first on Linux Tutorials, FOSS Reviews, Security News.

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| by Scott Kilroy

Stop image hotlinking on NGINX

If you think it’s possible that someone is linking to images hosted on your site add the following to you nginx config file # Stop deep linking or hot linking location /images/ { valid_referers none blocked www.linuxconsultant.org linuxconsultant.org; if ($invalid_referer) { return 403; } } Or if you want to be a wiseguy and replace the hotlinked image with something else # Stop deep linking or hot linking location /images/ { valid_referers none blocked www.linuxconsultant.org linuxconsultant.org; if ($invalid_referer) { return […]

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| by Scott Kilroy

Kill all process associated with a user

skill -TERM -u USERNAME

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| by Scott Kilroy

Force a user off the system

slay USERNAME

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| by Scott Kilroy

Linux Security

“Yes, I’m paranoid — but am I paranoid enough?” ― David Foster Wallace, Infinite Jest Hardening Public Servers Install system accounting On Debian based systems run ‘apt-get install acct’ then you can use commands lastcomm and sa to see who ran various comands. Also a log file will be writen to /var/log/account/pacct Remove compilers from production severs use the command ‘apt-get –purge remove gcc’ Setup remote logging See http://www.thegeekstuff.com/2012/01/rsyslog-remote-logging/ to find out how Install fail2ban Linux.com has a good intro to fail2ban http://www.linux.com/learn/tutorials/469597-weekend-project-keep-out-repeat-offenders-with-fail2ban-on-linux

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