Online regex checker | If you ever needed to validate regular expressions, this site is invaluable. http://regexpal.com This site has really saved my bacon more than once. Check it out!
Install BIND in Red Hat 6 or CentOS 6 | As of Red Hat 6 and CentOS 6, the DNS server bind is super easy to get up and running. Here’s how it works! Install bind: $ sudo yum install bind Start bind – the service is called named $ sudo /etc/init.d/named start Generating /etc/rndc.key: [ OK ] Starting named: [ OK ] Done. If
Bluetooth Hacking – ronin | I was fortunate to hear an excellent talk at my local lug by bluetooth hacker ronin. ronin has been featured at DefCon and other security conventions. He has written tons of awesome Linux based apps for bluetooth hacking. Check out http://www.hackfromacave.com. At this point I am completely paranoid about ever having bluetooth enabled in public.
Disable HTTP Compression in Apache | I’ll show you a quick way to actively check a server for compression as well as how to disable compression in Apache. Note: This has _no_ effect on the CRIME TLS vulnerability but does mitigate BREACH. | Test for Compression A simple test page to test for HTTP compression is here: http://www.gidnetwork.com/tools/gzip-test.php Or alternatively, below is a manual test for
iostat and vmstat – Awesome System Statistics for Linux | Two excellent Linux apps are iostat and vmstat. These provide realtime statistics of system IO and memory usage. Here’s how it works! iostat iostat is useful to view realtime stats of disk IO. I suggest running ‘iostat 1′ to have the command refresh each second. $ iostat 1 Linux 3.2.0-2-amd64 (brahms) 09/12/2012 _x86_64_ (4 CPU)
clamav Signatures not Updating Ubuntu Linux | Clamav will sometimes have trouble downloading updates for some reason or another. I’ll show you how to fix this in Ubuntu Linux! First, stop clamav: $ sudo /etc/init.d/clamav-daemon stop $ sudo /etc/init.d/clamav-freshclam stop Next we are going to manually download the latest signatures from clamav’s website and place them into the proper location in Ubuntu.
Fast Host Discovery with nmap | The easiest way to do host discovery is with nmap. nmap of course offers a variety of ways to probe and map out detected hosts and poke at any open ports or services. But as for a quick discovery, ICMP is ideal to just get a quick assessment of online hosts. I’ll show you how!
Encode or Decode base64 from the Command Line | If you have ever needed to quickly decode or encode base64, Linux has a command line utility called base64 that works great. I’ll show you how it works! To encode text to base64, use the following syntax: $ echo ‘scottlinux.com rocks’ | base64 c2NvdHRsaW51eC5jb20gcm9ja3MK To decode, use base64 -d. To decode base64, use a syntax
Example Interview Questions for Networking or Linux Jobs | Below are a few good interview questions for networking or Linux related jobs. These will give a relatively good assessment if the candidate has good knowledge of some fundamentals. Alternatively, this makes a great study guide if you are applying for any networking or Linux related jobs. Wikipedia is the best guide and much better
How to Manually Edit ufw Rules on Ubuntu Linux | ufw is the great command line app for managing iptables in Ubuntu. While any changes should use the ufw command, it is possible to rather manually edit user created ufw rules in cases where that might be desirable. The file location is: /lib/ufw/user.rules For ipv6 rules, the file is: /lib/ufw/user6.rules As with iptables, rules are