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Prevent Postfix Brute Force

Published on 2011/05/26, by in linux, sysadmin.

Prevent Postfix Brute Force | An often used attack vector is brute forcing MTA logins. While most admins watch ssh auth logs like a hawk, email auth/login logs are most often not closely watched for this sort of thing if at all. I’ll show you one way to easily prevent a Postfix brute force attack! This how-to focuses on fail2ban

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Select Fastest Debian Mirror for apt-get

Published on 2011/05/15, by in linux, sysadmin.

Select Fastest Debian Mirror for apt-get | With Debian you can easily auto-detect the fastest mirror for apt-get! First install this package: $ sudo apt-get install netselect-apt Then run the following, adjusting for your desired version. I’m using LMDE, so I’m going to run: $ sudo netselect-apt testing Other examples: sudo netselect-apt [stable|testing|unstable|experimental|release_codename|sid] This will query various debian mirrors then leave a

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Detect Network Cable Link in Linux

Published on 2011/05/04, by in linux, sysadmin.

Detect Network Cable Link in Linux | To check for the presence of a network link, use the command ethtool. For example, this checks eth0: # ethtool eth0 or $ sudo ethtool eth0 Look for a line which says ‘Link detected: yes / no’. The exact output may vary depending on your Linux distribution. Debian / Ubuntu looks like this: Red Hat

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Bash Tips – Return to Previous Location

Published on 2011/05/01, by in linux, osx, sysadmin.

Bash Tips – Return to Previous Location | Ok this is a quick one, but useful! To return to the previous working directory, simply type: cd – and hit enter. Cool!

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Batch Rename Files with rename

Published on 2011/04/24, by in linux, sysadmin.

Batch Rename Files with rename | How can I batch rename files in Linux? There are tons of how-tos and guides on using sed, mv, and other commands to batch rename files. However, a very powerful tool available in Debian and Ubuntu Linux is simply rename. The rename command can be used to mass / bulk rename files, file extensions, rename

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Hardending Red Hat Linux, OS X, and Windows

Published on 2011/04/13, by in linux, osx, sysadmin, windows.

Hardending Red Hat Linux, OS X, and Windows | The security folks at the NSA have online guides on how to secure Linux, OS X, and Windows operating systems. These are definitely worth a read of all articles even if an OS in question is not your main cup of tea. Here is the link: http://www.nsa.gov/ia/guidance/security_configuration_guides/operating_systems.shtml Page has been taken down This direct link

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CentOS 5.6 Released

Published on 2011/04/06, by in linux, sysadmin.

CentOS 5.6 Released | CentOS 5.6 is here! Edit: Official Announcement is up! Use torrents listed: http://lists.centos.org/pipermail/centos-announce/2011-April/017282.html

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Linode Review 2011

Published on 2011/03/26, by in android, linux, sysadmin.

Linode Review 2011 | This is mainly a screenshot review of Linode‘s excellent VPS hosting and online interface. A VPS you could say is somewhat between shared hosting and a dedicated server though it has its advantages over a dedicated host as well. Ok so here is what you get: Runs on Xen 4 core Xeon @ 2.27Ghz 512

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Set Password Expiration for Linux Accounts

Published on 2011/03/19, by in linux, sysadmin.

Set Password Expiration for Linux Accounts | For security, it is good to enforce password expiration. Here’s how you do it in Linux. Edit the file /etc/login.defs: sudo nano /etc/login.defs Here you can specify options for password expiration: PASS_MAX_DAYS 90 PASS_MIN_DAYS 7 PASS_MIN_LEN 14 PASS_WARN_AGE 7 Max Days: maximum life of a password Min Days: prevent a second change again for X

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SSH Password Login From Specific IP Ranges

Published on 2011/03/16, by in linux, sysadmin.

SSH Password Login From Specific IP Ranges | Want to require ssh keys from remote sources, but then allow ssh passwords from your local home network? It is easy to make this specific configuration or alter as desired for your server. I’ll show you how! 1. Edit the sshd_config file sudo nano /etc/ssh/sshd_config In this file, edit the existing line PasswordAuthentication to ‘no’

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