I read an article from Wired News this morning about a guy who posts information about case law online. He basically found an error in a court document, and after the judge on the case read about the error in this guy's weblog, he fixed it and credited this man for finding the error.
Anyway, the author of the article (maybe in quoting the weblog author) goes on about how people that have weblogs tend to have introspective postings, and frown upon those who have real-world content. I would rather have content for my blog than introspective rants about this and that. But hey, what else would I have to write about in outside life if not for my daily rantings, right?
Anyway, I just thought I'd offer a bit of information today that I conveyed at work. It's something that I've known for a while, but I guess it's not common knowledge, and although there really isn't much to figure out about it, it might not be obvious to people.
Did you know: You can telnet to any port on a server system, as long as there is some service running there and you know how to connect to it. In Windows, just get a command line, then type "telnet server.com 80", to try it as an example. Of course, nothing happens because the server is waiting for you to say something first. Everyone who was had to deal with servers of some kind knows that web servers run on port 80 (hence the "80" in the command above).
All you need to do at this point is tell the web server what you want. So type the following lines, pressing return at the end of each line:
GET / HTTP1.0 Accept: text/html
Press return again and you'll see a bunch of web server headers followed by the HTML for that site's homepage. Pretty simple, eh?
It turns out this is useful not just for web servers, but for mail servers, too. If you're insane enough to talk to an email server, you can connect to it on port 25. Sorry, I'm not familiar enough with that protocol to tell you how to get started. The only useful SMTP command I know is "QUIT". Type it on a blank line to stop talking to the SMTP server.
Why is this useful? Because it lets you test your servers for open ports. If you want to see if that web server you're running also has an SMTP relay open to the world, just telnet in on port 25 and see if you get a response.
Ok, so it's not much content, and not even worthwhile to most people, but it's still useful information to somebody. Maybe I'll forget this info and be relieved in the future when I'm reminded how. You know, that's not so far fetched, considering that I couldn't remember the formation of the GET line above. Oh, well, time to start taking my ginko-biloba before Alzheimer's sets in.
