The first video tutorial shows you what yEnc messages look like in your newsreader if your newsreader doesn’t natively support yEnc. This video will help you recognize yEnc messages so you know if you need a yEnc Decoder like yProxy.

The second video walks you through installing and configuring yProxy with your newsreader, but uses Windows Live Mail as the example newsreader.

The third video walks you through running yProxy for the first time and starting yProxy.

The fourth video demonstrates yProxy in action.

This allows you to use the proxy as a raw TCP proxy to route other TCP traffic.  yProxy can be used as a raw TCP proxy in such a manner simply by disabling the “yEnc Decode” feature, which turns it into a pure TCP proxy.

yProxy as a web proxy

For example, try the following setup in yProxy:

Be sure to set the port numbers also, and click the Start button to start the proxy server.  Then try entering this URL in your browser address bar:

http://localhost

You’ll see Google’s homepage show up.  What you’ve done is load Google’s homepage through the proxy.  Actually, you’ve got a little bit more work to do if you want to keep going through the proxy at this point because anything you click on goes to a google.com address instead of “localhost”, but you’ve gotten the point that yProxy can be a down and dirty proxy for redirecting TCP traffic.

yProxy’s TCP proxy options would be best used for other types of TCP traffic like email or FTP, where the client doesn’t try to make connections to other domains.

yProxy as a remote web proxy and port obfuscator

The above example doesn’t really make much practical sense, but imagine that your school or work attempts to blocks all web traffic by blocking all traffic on outgoing port 80, but they do allow SSH traffic over port 22.  Leave yProxy running at your home with the following configuration:

Disable yProxy’s ”Run Locally Only” option and, as before, click Start to start yProxy.

Then from your school or work computer enter the following URL into your browser’s address bar:

http://10.2.0.96:22

You’ve just loaded Google from your home over port 22.

Note: I cheated in my example.  10.2.0.96 is actually a private IP address.  You’ll need type your public IP address into your web browser.  If you’re behind a NAT router at home, you’ll have to find out what your public IP address is and enable port forwarding or plug your computer into the DMZ port.  To find your public IP address, go to http://ifirefly.com.

yProxy as a remote FTP proxy

What if your friend is running an FTP server, but for security purposes, he only allows you to connect from your home IP address.  You’re going to be on the road though, and you still need to access the FTP server, but you don’t want to bother your friend to change his server’s configuration.

Use the following configuration for yProxy:

Well, FTP uses a second port for data, so you’ll need another instance of yProxy running to actually download anything:

Again, you need to turn off the “Run Locally Only” option for yProxy and press the Start button to start the proxy servers.

Now, you can enter this address into your FTP client or web browser:

ftp://10.2.0.96

Your computer at home is connecting to your friend’s FTP server, and you’re connecting to your computer at home, so as far as your friend’s server is concerned, you’re still at home.

yProxy is more than just a yEnc decoder

There are other legitimate uses for a TCP proxy.  Please let me know what you come up with.

yProxy stands apart from other yEnc decoders.  yProxy is a true TCP proxy underneath.  Have fun.

yEnc has more advantages than simply being smaller in size.  yEnc also ensures that the file has been delivered intact via two methods:

• CRC32 Error Checking
• File Size Checking

If you yEnc decoder doesn’t support the above features of yEnc, not only are you losing out on some of the benefits of yEnc, but your yEnc decoder is not even yEnc compliant.

CRC32 Error Checking

yEnc CRC32 error checking uses a technology similar to what CDs and DVDs use to check for errors.  It uses a mathematical algorithm at creation time to generate a checksum value based on the data and stores that checksum on the data.  At play time, the value is recomputed against the data and compared against the stored value.  If the checksums do not match, then an error has occurred while reading the data.

In order for a yEnc Decoder to be compliant with the latest yEnc standards, a yEnc Decoder must include CRC32 error checking.  All yEnc attachments have the CRC32 checksum, and if your yEnc Decoder isn’t evaluating the checksum, then you won’t know when you’ve downloaded a file that has been corrupted or modified since it was created.

You may download that treasured song that you’ve been looking for, then when you go to play it back, it may not play or it may contain defects.  At that point, it may be too late to try to download the song again from another source.

Embedded yEnc Decoders will not provide CRC32 error alerts.  yProxy notifies you immediately when an attachment with an error has been detected.  yProxy beeps and changes the system notification icon to one with a large red exclamation mark, in addition to logging the error.  None of yProxy’s competing yEnc proxies provide CRC32 error detection.

File Size Checking

The file size is also computed at creation time and stored in every yEnc attachment.  All yEnc compliant yEnc Decoders must check the final file size against the stored value.  If a file has been truncated by the news server or parts of it are missing, the file may be unusable.  It is important for your yEnc decoder to be able to determine the difference between a corrupt file and an incomplete file.

If the file is incomplete, you may simply need to try again later after the file has finished propagating.  An incomplete file may still be usable, depending on the type of file.  An MPEG video file with the last second missing will still be playable, and you may not notice that missing second.  Therefore, it is important for your yEnc decoder to distinguish between a corrupted file and an incomplete file.

yProxy notifies you immediately if the downloaded file size does not match the expected size.  yProxy will beep and place an exclamation mark in the system notification icon, in addition to logging the error.  The error displays the expected file size and the actual file size so that you can determine the extent of the problem.

Embedded yEnc decoders cannot check the file size and none of yProxy’s competing yEnc proxies provide file size checking.

yEnc Decoder Compliance

CRC32 error checking and file size checking are valuable features of yEnc encoding.  yEnc decoders must support both CRC32 error checking and file size checking in order to be compliant with the latest yEnc standards.  yProxy is the only yEnc decoder proxy that is yEnc compliant.