Hi, this technical blog will contain urls/tutorials that relate to latest technology. More so, I will also attempt to write tutes on my own to simplify things that are too complex. Thanks for your time in checking out this blog.

Thursday, December 22, 2005

LINQ Framework

LINQ or Language INtegrated Query is a set of classes in .NET that allows you to query arrays just as would query a database, using keywords such as 'select', 'where' etc.

Sounds interesting?? I'm just exploring it. Have a look at these sites in that order.
1. http://blogs.msdn.com/danielfe/archive/2005/09/13/464904.aspx
2. http://blogs.msdn.com/sriram/archive/2005/09/16/468927.aspx

There is also a video at channel9...Do check it out...http://channel9.msdn.com/showpost.aspx?postid=114680 and here is the related MSDN link that offers a lot of code samples and downloads.

By the way, it is supposed to be shipped with the next version of Visual Studio (Orcas).

Monday, December 05, 2005

Insecure SMTP...


You may be knowing about SMTP. Its called Simple Mail Transfer Protocol. SMTP is responsible for transfering mails from 1 server to another server. Suppose you want to send a mail from yahoo mail to gmail, the yahoo server sends the mail to the google server through SMTP. To know in detail about the SMTP sepcification, refer RFC 2821 at ietf.org.

Coming back, when a mail is about to be sent, a domain called the "Mail Exchanger (MX)" is contacted, which relays the mail to the destination. The mail exchanger works on default smtp port (25). This MX can be contacted directly by bypassing the usual web interface (that we are used to) and thus anonymous mails can be sent!!! Sounds dangerous?? Read on....

For example, lets take a fictitious website called http://www.abcdefghij.com/ and lets assume its having a MX. In linux OS, we use the dig (i don't know the windows equivalent) command to retrieve the MX record of a website. On issuing the command at the terminal,

dig abcdefghij.com mx

a list of url's popup as the result. Look for ";; ANSWER SECTION". At the end of the line, there will be a url which is the mail exchanger. Ofcourse, a website may have many MX records.

Now, we have to connect using telnet to port 25, the standard SMTP port at any of the MXs.

telnet mx1.abcdefghij.com 25

Your output should look similar to
Connected to mx1.abcdefghij.com
Escape character is '^]'.

For each line of command you type, you will get a response. Normally, an email will have a from address, to address, subject, content. Issue the next command as follows.

MAIL FROM:<xyz@abcdefghij.com>
503 // Server output
RCPT TO:<abc@abcdefghij.com>// The angular brackets are mandatory
Subject: this is subject // A blank line is a must after this line

this is the content
. // '.' (dot) signifies content end
221 mx1.abcdefghij.com
Connection closed by foreign host

Your mail will be sent now. Almost no servers will support foreign relaying. That is, if u want to use the MX of yahoo the 'MAIL FROM' should have its email address ending in yahoo.com or something that the yahoo servers support. The 'RCPT TO' can be any valid email address. Have a look at this url http://www.yuki-onna.co.uk/email/smtp.html for having a detailed explanation on sending mails using SMTP & terminal

Why this is insecure??
It allows emails to be sent without logging in. Only the domain of FROM address is checked to see whether its legal for relaying. That too, the email address is not verified. Therefore, unscrupulous spamming is a possibility. Connecting on normal SMTP offers a bit of security because, the email address is verified for its existence.

Hope this helped a bit.....bye!!~~

Monday, November 28, 2005



AJAX or Asynchronous Javascript & XML seems to be the coolest or hottest (in whichever way u want) technology around. It deals with sending asynchronous requests to the server behind the scenes, and its a very good way of showing interactive content.

It comes with lot of advantages. One of them being; large data driven websites need not refresh whole pages of data always to display new content. Gmail is 1 of the many sites that uses AJAX heavily.

In .net, AJAX is implemented as "Atlas" and in J2EE, any app server that supports servlets will support AJAX.

To know more about it, follow the wikipedia link. Check out the Atlas link to know more about it in .net. As for J2EE, read this excellent article on implementing AJAX. As usual, there are some FAQs as well and some common pitfalls that you should avoid.

Happy coding bye!!~~

Sunday, November 27, 2005

Yay!! New Tech Blog

hey guyz n galz, this is my tech blog.....plz return here. i will be updating this often. Meanwhile, chk out my non-tech blog.