Category: Server

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iotop: How to monitor processes that hogs hard disk writes

iotop is a small and handy tool to monitor processes that hogs I/O resources. iotop outputs is similar to ‘top’ except it lists the hard disk read/write activity as well as swap writes.

You can use the left and write key to sort the heading according to your preference and the R key can be used to reverse the sort. The ‘O’ key is used when you only wants it to display processes that are currently utilizing the disk I/O. While the ‘P’ key can be used to display accumulated IO disk read/write for all the processes (which can be sorted with the arrow keys).

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BlackBuntu – Ubuntu-flavored Linux Penetration Distro

Blackbuntu is a Ubuntu-based distro used for penetration testing and security auditing. Blackbuntu is designed to be used by students and practitioners who are interested in the field of information security.

Blackbuntu tools are divided into several categories:

  • Information Gathering
  • Network Mapping
  • Vulnerability Identification
  • Penetration
  • Privilege Escalation
  • Radio Network Analysis
  • VoIP Analysis
  • Digital Forensic
  • Reverse Engineering
  • Miscellaneous

Which includes these tools among others: Lanmap2, nmbscan, dnsmap, fierce, hostmap, ltrace, tctrace, sqlbrute, sqlmap,sqlninja, mysqloit, sqlcheck, wfuzz,xsser,xssploit,jmeter, nikto2,skipfish,wbox, autopsy,scalpel,mboxgrep,galetta,afstats, wepcrack,giskismet,fakeap,aircrack-ng,cowpatty,bluebugger,bluescan, bluesnarfer, iwar,protos-sip,sipcrack,brutessh,hydra,sshater

…and many more.

Blackbuntu can be downloaded from its official website – http://www.blackbuntu.com/

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AMD decTOP running Debian Squeeze

After upgrading my AMD decTOP with 160GB hdd, I’ve decided to install a fresh new operating system on it for some side-project that I’m working on. I choose to install Debian GNU/Linux 6.0.3 (Squeeze) on the machine.

The machine is currently running lighttpd web server with PHP5, samba server and sshd (using public-key authentication).

The specs of the machine are outlined in the screenshot.

dectop

You can read more information regarding AMD DecTOP on Wikipedia

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Ubuntu: How to create a lot of entropy for GPG key generation from command line

Desktop Ubuntu users may have several ways to generate entropy relatively secure GPG keys (=>2048 bits), usually by moving the mouse and by typing random words. However this creates certain problem, for command-line user (especially those who are connecting through remote VPS connection).

Here’s a tip on how to produce enough entropy for GPG key generation:

  • apt-get install rng-tools
  • rngd -r /dev/urandom
  • then, proceed to generate GPG keys as usual: gpg –gen-key

Hopefully this tips will help you get by generating GPS keys over those VPS connections!

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How to limit cpu usage for a process with cpulimit (Ubuntu / Debian server)

cpulimit is a tool that can be used to limit cpu usage (throttle cpu usage) for a single process (by its PID). cpulimit is useful to ensure that a single process would not hogs the cpu cycles, which can be use by other processes. cpulimit is different from ‘nice’ as it limits the real cpu usage for a process, while ‘nice’ controls scheduling priorities for a particular process.

How to use cpulimit?
Basic usage:
[bash]
cpulimit -p [pid] -l [ cpu percentage]
cpulimit -p 12345 -l 25
[/bash]

Running cpulimit on background:

[bash]
cpulimit -p 12345 -l 25 -z -b
[/bash]

Note: The cpu percentage is the same one as reported by the ‘top’ command.

cpulimit can be installed from Ubuntu and Debian 6.0 (Squeeze) repository through apt-get. The official website of cpulimit is http://limitcpu.sf.net

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Pingness.com: Free service to monitor website uptime

It is undeniable that uptime is important for business and personal websites. For example, a website with low uptime may mean that the host is having technical problem or the web server is overwhelmed by client requests (serving web pages may incur a lot of overhead)

Pingness.com service does not require sign-up, you need to submit your email address and website url, and pingness will send reports of your site downtime (if any) and when the website is back-online.

pingness