Category Archives: Network

Internet. Networking.

Tunneling with libcurl

As I wrote a while ago, companies using http proxies make people feel a need to break out of their proxies.

Bryan is a friend who recently found out that his company is switching proxy to a different one and apparently both corkscrew and proxytunnel have problems with this new piece, and since libcurl offers quite a lot of functionality to accomplish almost this, a new project was born: curltunnel.libcurl

One immediate benefit of using libcurl is the support for multiple authentication methods, in fact more than any of the above mentioned tools.

However, it seems our first quick stab at making this tool (currently 278 lines of code), made it work for several common cases but… not for Bryan’s new proxy.

The current theory is that the proxy actually checks for SSL traffic and only lets that through, and thus it prevents the ssh server banner to appear when we try to tunnel through the proxy to a remote ssh server on port 443. If further testing proves this correct, we will of course have to add a SSL layer to the mix.

download flv videos from youtube

My wife wants to keep some videos found on youtube, and I really can’t recommend just keeping bookmarks to a random web site like that. Not if you want the content to be available in a few years ahead, or even ten or twenty years. Then downloading the files to keep the locally is the only sane way to make it somewhat more reliable.

To download the files you can do it with a browser or with a command line tool:

Browser StyleGreasemonkey

  1. Use Firefox
  2. Install Greasemonkey
  3. Within Greasemonkey there’s concept of user scripts that customize it, and we want a certain customization for youtube pages. So we get the YouTube to me v2 script installed.
  4. Now, each youtube web page gets a red stripe on the top of the page that allows you to download the FLV.

Command Line Style

There exist several command line tools “out there” that do the job. I tried youtube-dl and it did the job splendidly by only proving the main HTTP URL on the command line.

The main lacking feature is that it names the output flv based on the ‘v’ variable in the URL so the downloads end up being named things like “f_8wuVEYMZ8.flv”…

Play the local FLV movies

For this, I can only recommend the lovely VLC media player, available on all modern platforms.

Form Submit Honeypot by Mistake

During the summer 2001, me and my wife toured Vietnam and we had a great time. For that occasion I set up a little online diary that would allow us to post entries while on the road, to allow our families and friends back home to be able to keep up with what we were doing.Boats in Vietnam

Fast forward to present day: the diary “submit new entry” form is still left on my site, and while it no longer works (it hasn’t worked for many years) – it is still one of the most visited pages on my site! It seems the automated spam bots find it and submit crap to it… the crap doesn’t end up anywhere to be seen nor is it even stored on the server, but it clearly identifies evil machines! Isn’t that a honeypot as good as any?!

So far during September 2007, no less than 309 unique IP addresses have issued a POST on that page..

Break Out Of That Proxy

SSH proxy functionality overview

Far too often we end up behind a proxy that limits our network access in one or more ways. There are however clever ways that in most cases allow us to work around the nuisances the proxies impose, and I’ve written down my “guide” on how to do it here!

This is a procedure I’ve used myself many times and I’ve ended up explaining it to others several times as well so I felt it was about time I wrote it down.

I’ve tried to catch most quirks and be detailed and accurate, but please point out if you find any errors or mistakes in there. I hope to be able to perhaps add more specific config examples and command lines as well to make it even easier to follow.