Category: Computers

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How to Synchronize Current Time in Ubuntu

As some of you might aware, the time kept by computers (or other timepieces such as clocks) are not accurate as there are various factor that causes time drift. Quartz inaccuracy, temperature, quality of the equipment, power from battery, mechanical wear and tear and so on.

These minor drift while might not seems to be significant, it will give you inaccurate measure of time. This might affect your other productivity work as the time kept by your computer is not accurate to the last second. Plus, certain application such as Stellarium and GPredict depends heavily on the time kept on your computer to give accurate result.

How to get accurate time in Ubuntu
You can ensure your computer gets the most accurate time by synchronizing it with an NTP server .

To do this you need to right click the Tray Clock in Ubuntu, and selects “Adjust Date & Time”.

Adjust Date and Time

A dialog will appear, press “Unlock” and enter your Administrator password to enable the menus.

Adjust Date and Time

Answer “yes” to install NTP packages. If your computer is connected to the internet it will be automatically synchronized with an NTP server.

Bonus :You can select the nearest NTP server to your place for faster synchronization, as shown on the picture. The nearest NTP server to Malaysia is maintained by SIRIM – mst.sirim.my.

NTP Time Servers in Ubuntu

Synchronize Time using command-line
Alternatively you can synchronize time by using ntpdate command-line tool, which is covered previously in this blog.

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Ubuntu Mobile is going to be announced in June !

Good news everyone, Canonical is going to announce the latest edition of Ubuntu line up, Ubuntu Mobile next month. Ubuntu Mobile is an Ubuntu edition which runs on a new type of mobile computers called Mobile Internet Devices.

Some features of Ubuntu Mobile device are :

  • GPS
  • Digital TV
  • Emails, Instant Messaging, Web Browsing
  • Multimedia Player
  • VoIP applications
  • Integration with various social webapps (MySpace, Youtube, Facebook)
ubuntu logo mypapit.net

However it is stll remain to be seen whether Ubuntu Mobile going to released with its own SDK. I’ll be really excited if they release Ubuntu Mobile in my place.

Source : Underexposed – CNET News.com

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The friendly Old Battery Warning in Ubuntu

Ubuntu is friendly enough to provide a nice and friendly warning to me about the status of the laptop battery that I currently use. With Microsoft Windows (at least Windows XP), the laptop simply dies when the battery looses its juice.

old and broken battery warning

Its nice to have this sort of reminder when you really need to change the battery.

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ssh-vulkey : How to test weak SSH keys on your server

This might be stale news by most security alert people, but I felt compelled to write this post nevertheless. Byy this time most security alert people have realised that a serious security vulnerability has been discovered in the random number generator used by OpenSSL on Debian and Ubuntu systems, and there are a lot of sites have published information about it. [1] [2] [3] [4] [5].

This vulnerability caused OpenSSL to generate “common” and predictable keys, which is easily crackable by using brute-force algorithm. In the extreme case, some of the keys are successfully cracked in 2 hours time. Longer keys 8192-bit RSA keyset might take as short as 129 days to generate as opposed to hundred of years if the keys were generated securely.

Which Ubuntu Linux system are affected ?
As Ubuntu linux operating system is based on Debian, it inherited Debian vulnerability problem. Users who has generated keys under (before updating to the new OpenSSL package via automatic updates, which is before May 13 2008) — Ubuntu 7.04 Ubuntu 7.10 Ubuntu 8.04 LTS are all affected by this vulnerability

Other system which uses the keys generated by Debian and the above mentioned Ubuntu system is also affected as the keys might allow malicious 3rd party user to abuse the system. SSH login which uses these keys will not be considered secure anymore, and are advised to update their SSH keys immediately.

How to check against weak SSH keys ?
A system is as strong as its security measures (in this case, the key) to protect it. By using ssh-vulkey as detailed in Ubuntu Security Notice 612-2, you can detect weak keys in your system, and updates them accordingly.

Run “sudo ssh-vulnkey -a” command to check against weak keys :

ssh-vulnkey -a

ssh-vulnkey -a
Not blacklisted: 2048 fa:2e:1d:a6:84:64:a1:80:c4:31:68:5a:b0:1a:cb:fe /etc/ssh/ssh_host_rsa_key.pub
Not blacklisted: 1024 f4:34:04:85:58:a0:6b:0a:a1:b9:2d:3b:e6:19:5a:76 /etc/ssh/ssh_host_dsa_key.pub
COMPROMISED: 2048 5c:10:8a:c0:55:8c:1f:d9:4b:05:f0:35:0a:0d:2f:5c /home/someuser/.ssh/authorized_keys
Not blacklisted: 2048 a7:b4:3e:41:18:cb:f7:68:5e:4f:ae:30:14:d2:17:fd /home/someuser/.ssh/authorized_keys

More information about OpenSSL in Debian / Ubuntu security vulnerability :