Sunday, February 26, 2012

"Additional log on information may be required." NOT ANYMORE!

NOTE: This method is not at all reliable. cron jobs work better than startup scripts. But it seems that the cron implementation in DD-WRT is broken. So I switched to using TP-LINK router which happily run the more sturdy OpenWRT. OpenWRT handles cron jobs very reliably, look at my newer blog post on how to configure a router running OpenWRT to login to your Reliance Broadband automatically - this new method using cron has proved to be quite successful for me.

---Introduction, skip this if you already know what you are here for

You reach home after a long day at office and are looking forward to catch up with friends on facebook. You weren't able to do so at office 'coz the internet there is terribly restricted and you have recently cancelled the 3G data plan on your cell phone. You turn on the WiFi router and wake up your laptop from sleep mode and this message pops up!! So the first webpage you are forced to visit is your Internet Service Provider's to login to your account. This isn't that big a deal, only slightly irritating - which you can do without at the end on an already frustratingly long day. Also if you have gifted your mom an android phone and are teaching her to use the Skype App on it, you better have a WiFi enabled internet connection without any login hassles, otherwise the whole activity would be anti productive. Gone are the days when ISPs were PPPoE friendly - you could configure your WiFi router to "dial in" to the ISP automatically at power up and all your "browser less" embedded gadgets could then access the internet without blinking error LEDs or showing an error message on the small LCD.

--- end Introduction

So if your ISP requires you to login via the web, you can definitely do something about it. Here's my specific setup:

Location: Mumbai India
ISP: Reliance Broadband
Hardware Setup: Linksys WRT320N WiFi router. A CAT5 cable from the switch installed on my apartment building's terrace travels thru a duct, enters my room through a whole in my window frame and crawls to my desk and plugs in to the back of my router - into the RJ45 jack labelled Internet. CAT6 cables from Seagate BlackArmour 110 (Network Attached Storage) and HP Deskjet 4500 (Fax-Scanner-Printer) plug into the LAN ports of the router.

Of course you can write script and run it at startup on one of your computers - this one must boot up before other devices on your LAN are able to access the internet. Refer to Kunal Dua's post on how to do this. (Related Links and Discussions: Reliance Broadband – New Auto Login Script| Automate irritating ISP login | Forum Post 1 | Forum Post 2)

I wanted to take this one step ahead by entrusting the task of logging in to my router. And this I did as follows:


  • You might mess up your router if you don't follow the steps properly and in sequence.
  • This is only good for "login" and not for "logout". So if you do not have an unlimited internet plan (unlimited in terms of data transfer as well and online time), do not use this.
  • Check if your router is supported by DD-WRT by searching for its model number in DD-WRT's router database. Proceed only if this is true.

Steps that I followed for the Linksys WRT320N router, you can follow similar steps for your router modify them as applicable:
  1. Logged in to my Router's management webpage and noted down any settings that I would require to re-configure the router after flashing it with the new Operating System (i.e. DD-WRT). Noted down things like SSID, WiFi Password, MAC Address Cloning entry etc.
  2. Downloaded dd-wrt.v24-14471_NEWD-2_K2.6_mini_wrt320n.bin and saved it on my Laptop. Looked this up from DD-WRt wiki page for WRT320N here.
  3. Downloaded dd-wrt.v24-14896_NEWD-2_K2.6_big.bin  and saved it on my Laptop. This was the latest version for my router as reported by DD-WRT's router database. This version is for routers with 8MB flash and has lots of extra features over and above the "mini" versions (look here for comparison).
  4. Removed all cables from the 4 LAN ports of the router. Disabled my Laptop's WiFi. Installed a CAT6 cable between the LAN port of my Laptop and one of the four LAN ports of my WiFi Router. Left the internet cable plugged in to the router.
  5. Reset my router using the 30-30-30 method as specified here.
  6. The router was restored to the factory setting. Logged in to the router's management webpage which opens by default at (default username: admin and default password: admin) after a reset.
  7. Performed firmware upgrade using dd-wrt.v24-14471_NEWD-2_K2.6_mini_wrt320n.bin
  8. Reset my router using the 30-30-30 method as specified here.
  9. Logged in to the router's management webpage which opens by default at Was forced to set a username and password.
  10. Performed firmware upgrade using dd-wrt.v24-14896_NEWD-2_K2.6_big.bin
  11. Logged in to the router's management webpage which opens by default at Was forced to set a username and password.
  12. Performed basic configurations like SSID, WiFi security settings, MAC Address cloning setting, local LAN IP, Time/NTP setting etc. etc.
  13. While still on the management webpage of the router (which of course is now different because DD-WRT is now installed on the router), switched to the Administration tab and then the Commands tab.
  14. Typed the following line in the commands textbox (assuming my username is 1234567890 and password is reset123):
    wget '' -O /dev/null
  15. Clicked the "Save Firewall" button. (This will cause the router to execute the login command everytime DD-WRT's firewall service starts - which is after every boot up and initialization of the Internet/WAN Port. The firewall service can and must be enabled even if you are not going to set any firewall rules)
  16. Logged out of my internet account via Reliance Broadband's web page.
  17. Powered down the router and powered it back up again.
  18. Tried accessing using a web browser on my laptop - it loaded up without the Internet Service Provider's login web page popping up instead. Project Successful!
ISP, Reliance Broadband, PPPoE, automate web login, DD-WRT, wget, browser login, Internet Service Provider, auto login, 

Thursday, February 16, 2012

Piezoelectric sensors and actuators

A Tutorial on various kind of Piezoelectric transducers from Open Music Labs:

Saturday, February 4, 2012

MAX232 Reference

'Coz I keep forgetting the directions of the RS232 signals all the time.

Friday, February 3, 2012

Warts on a wall wart

This is what happens when you plug in a AC/DC adapter meant for mains input of 110VAC/60Hz (USA/Japan) into a 230VAC/50Hz (India). AC/DC adapter is a simple Stepdown Transformer > Bridge Rectifier > Capacitor type. You can see from the pictures that the windings on the primary side heated up and melted and shorted out. The heat also caused some insulation to melt and ooze out of the transformer. 

It seems the wall wart (colloquial for AC/DC Adapters) has grown warts of its own! Hemorrhoids even!!