password-less ssh login

– On local machine, generate key pairs by


follow the prompt, enter nothing as password, a pair of key files (id_rsa, is generated in folder .ssh

– Copy the file .ssh/ to the .ssh folder as new name “authourized_keys” via scp, command as below:

scp .ssh/

That’s it!


How to use 3G Internet in Vietnam


From my travel experience, Internet is really saving awkward foreign travellers bunch of hassle. So, here come the time-saving tips on how to use Internet on your smart phones (iPhone, Blackberry, any phone that have 3G function works).

Step 1:

Once you arrive in Vietnam, find any phone-card shop (wherever you see a sign listing all kinds of carriers’ names, must be it). Ask for Vinaphone SIM pack. The credit you get on the first charging is always at least double, sometimes triple the amount you pay. Depending on your stay, pick suitable kit. As of July 2010, for a week, I suggest the 180,000VND (which get you 360,000 VND credit). More on SIM pack tip later, at the footnote.

Step 2:

Compose a message with content “GPRS ON” (without the quote), send to 333 or 888.

Step 3:

Compose a message to send to 888, with content as listed down here, according to your usage

SMS content Price Bandwidth
M10 ON 10,000 VND/30 days 10 Mb
M25 ON 25,000 VND/30 days 35 Mb
M50 ON 50,000 VND/30 days 100 Mb
U1 ON 12,000 VND/days unlimited
U7 ON 80,000 VND/days unlimited
U30 ON 300,000 VND/30 days unlimited
That’s it! Enjoy Internet on the go!
Note on SIM: As mentioned above, first charging will get you double/triple credit, unfortunately it doesn’t apply to recharge. So if you don’t really care about your phone number, after using up credit, just ditch your SIM and buy a new one.