Tuts4Tech

Understanding and Preventing Fork Bombs

A fork bomb is just a bash function that gets called recursively. Once a fork bomb is active on a machine it may not be able to preform normally until a reboot is made, as the only solution to the fork bomb is to kill all its processes. Bash Functions A fork bomb is really just a [...]

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Passwordless SSH login using SSH Keys

SSH keys allow you to login without requiring you to type in your password this tutorial will teach you how to set them up First we need to create the key ssh-keygen -t rsa Then we need to move it over to the machine that we want to be able to login too without the need for a [...]

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Chroot Sftp

Create a Chrooted group addgroup chrooted Open up /etc/ssh/sshd_config and add the following to the end of it Subsystem sftp internal-sftp Match group chrooted ChrootDirectory /home/%u X11Forwarding no ForceCommand internal-sftp Restart SSHD /etc/init.d/ssh restart Then make users chrooted by adding them to the chrooted group adduser user chrooted Now when the user sftps the server they will only see the contents of there home folder

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Stopping SSH brute force attacks using iptables

If your running a SSH server on the default port(22) you've probably noticed a lot of failed login attempts cause due to brute force attacks Adding the following to your IP tables will only allow 3 connections at once from any IP if it goes above 3 then that IP is locked out for 3minutes. At [...]

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Linux File Permissions

What is chmod? Chmod is a command that changes the access permissions of files or directories in order to read, write or execute files How do I view The permissions of files? You can do this by typing ls -la Heres is a example of its output root@duffys-place:/etc/lighttpd# ls -la total 20 drwxr-xr-x 4 root root 4096 2009-03-29 00:36 . drwxr-xr-x 79 root [...]

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