Tuesday, December 08, 2009

Securely Delete Files on your Computer

here are times when you really want to make sure a file on your computer is deleted and can't be recovered by a PC expert, I am sure I don't have to preach about how it is really important these days to 'securely delete' your files.

Remember your files with any financial records or personal information can of course lead you to being ripped off by a ID fraud type criminal. If such criminals can undelete files on your hard drive and access the content then your security has been badly compromised. Also when you sell a computer, give an old computer to someone or indeed dispose of it, its important to securely delete all your data. There are BOOT CD's like DBAN which can dlete everything from a computers hard disk, however the best mother is to have the physical disk crushed by an expert company

Anyone these days can be a dleted file receovery expert, there are free utilities for windows like "Recuva", which can restore nearly any file that has not been 'securely deleted', thus anyone can be a instant expert with one google search......Dangerous i am sure you will agree.......However secure deletion is pretty easy to use. (Also i would encourage you to use recuva as way of getting files back that have been non securely deleted in error -- see here www.piriform.com/recuv )

What is secure deletion?

A clever professor has worked out a way deleting a file securely from a computers hard disk using a a technique that overwrites the data over 30 times with random bit patterns. see here http://en.wikipedia.org/wiki/Gutmann_method

Also take caution when using these secure delete programs as once the file is SECURELY DELETED its GONE FOR GOOD. No good calling me and asking me to perform some IT magic as the file is REALLY DELETED FOREVER

WINDOWS XP/VISTA/7 USERS

The free windows deletion utility "ERASER" implements this GUTTMAN technique and is the ONLY way of making sure deleted files are REALLY deleted forever on Windows......download and install from the link below and make sure you turn on GUTTMAN deletion from the options.

You can right click on a file and ERASE it securely, you can also do this with the Windows Trashcan, where deleted files are stored for recovery (its the icon like a dustbin on your desktop.

You should note that if you are deleting a lot of files at once it can take a long time, i had to securely delete on a Linux system 16 gig (4 DVD's worth) of data and it took over 24 hours. However for single files and anything under 1 gig ERASER is quick enough.

Website & Download for Eraser

http://eraser.heidi.ie


MAC USERS

For mac users , you need to CAREFULLY follow this guide from Apple on secure deletion

http://docs.info.apple.com/article.html?path=Mac/10.4/en/mh475.html

LINUX USERS

To delete from the Linux command line Install the 'secure delete' package from your Linux vendor, this gives you a command line utility "SRM" or in some cases "shred" or "wipe"

To securely delete from the GNOME GUI follow this guide below

http://www.webupd8.org/2009/09/delete-files-securely-in-nautilus-linux.html

To securely delete from the KDE GUI follow this guide below

http://www.kde-apps.org/content/show.php/Secure+Delete+Servicemenu?content=75734

Hope this helps you out in some way.

Monday, December 07, 2009

Linksys & Gentoo

My brand new home mysql server had a hiccup on install, very strange set of circumstances regarding name resolution. I had installed the latest version of Gentoo on a very mediocre specification PC to act as a MYSQL server on home network, really to aid my self education in coding in Python. Everything went well apart from after the install the server stopped resolving names to IP addresses, preventing me from updating the server. I tried all the handbook instructions on editing the /etc/conf.d/net file as otherwise /etc/resolv.conf gets overwritten on each boot, nothing worked, see my files below


tail /etc/conf.d/net
# This blank configuration will automatically use DHCP for any net.*
# scripts in /etc/init.d. To create a more complete configuration,
# please review /etc/conf.d/net.example and save your configuration
# in /etc/conf.d/net (this file :]!).
# dns_domain_eth0="csynet.co.uk"
#dns_servers_eth0="192.168.0.1"
config_eth0=( "192.168.0.10 netmask 255.255.255.0 brd 192.168.0.255" )
routes_eth0=( "default via 192.168.0.1" )
dns_servers_eth0="192.168.0.1"

ifconfig
eth0 Link encap:Ethernet HWaddr 00:0d:87:36:d7:c7
inet addr:192.168.0.10 Bcast:192.168.0.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:330 errors:0 dropped:0 overruns:0 frame:0
TX packets:157 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:41204 (40.2 KiB) TX bytes:13607 (13.2 KiB)
Interrupt:11 Base address:0xd400

lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:45 errors:0 dropped:0 overruns:0 frame:0
TX packets:45 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:810 (810.0 B) TX bytes:810 (810.0 B)

tail /etc/resolv.conf
# Generated by net-scripts for interface eth0
nameserver 192.168.0.1

db ~ # ping 192.168.0.1
PING 192.168.0.1 (192.168.0.1) 56(84) bytes of data.
64 bytes from 192.168.0.1: icmp_seq=1 ttl=255 time=0.773 ms
64 bytes from 192.168.0.1: icmp_seq=2 ttl=255 time=0.758 ms
64 bytes from 192.168.0.1: icmp_seq=3 ttl=255 time=0.759 ms
^C
--- 192.168.0.1 ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2003ms
rtt min/avg/max/mdev = 0.758/0.763/0.773/0.023 ms
db ~ # ping 195.112.4.14
PING 195.112.4.14 (195.112.4.14) 56(84) bytes of data.
64 bytes from 195.112.4.14: icmp_seq=1 ttl=53 time=18.8 ms
64 bytes from 195.112.4.14: icmp_seq=2 ttl=53 time=18.6 ms
64 bytes from 195.112.4.14: icmp_seq=3 ttl=53 time=19.1 ms
64 bytes from 195.112.4.14: icmp_seq=4 ttl=53 time=18.5 ms
^C
--- 195.112.4.14 ping statistics ---
4 packets transmitted, 4 received, 0% packet loss, time 3026ms
rtt min/avg/max/mdev = 18.535/18.793/19.110/0.252 ms
db ~ # ping ntp.nildram.co.uk
ping: unknown host ntp.nildram.co.uk

However the forums on the gentoo website provided some bright ideas, like not trusting my Linksys adsl router DNS resolver (192.168.0.1) to work with gentoo. Having changed the DNS to the opendns server the problem was solved. I found this very strange, all my other Linux PC’s at home resolve via the linksys with no issues, even my virtualbox hosts use the same resolver with no issue. If anyone has a sensible answer about why gentoo is different I would appreciate a tip. By the way thanks to those at the gentoo forum users for the smart suggestions.