I just received an unusual (I've never seen before, personally) error when connecting to Asia, even thought I was allowed to connect, something weird happened when I logged into the client. Here are two screenshots, one of the error, and one of me having a plug in the game client on Asia server.
The error:
http://img145.echo.cx/my.php?image=wasiaudperror8td.png

The ingame plug:
http://img145.echo.cx/my.php?image=clientplug9vy.png

You connection cannot pass things through port 6112 correctly, perhaps firewall blocking it. So then blizz decides no point on letting u play cos ur connection is blocking it. Try configuring ur firewall or something. Or try reconnecting

I highly doubt that, considering I don't use a firewall. I've never received this error before. However (no flaming, :/) I've had some winbots going forever, and they randomly disconnected from Asia. I then tested a stealthbot on Asia and it worked fine. After that I tried the game client, and this happened.
Update: I'll probably just reconnect. Qwerty, I like that quote from me. :)

[quote author=Yegg link=topic=11353.msg109416#msg109416 date=1114184548]
I highly doubt that, considering I don't use a firewall.
[/quote]

Thanks for the new sig addition!

Umm, I don;t get what's so great about it. I dont use a firewall. Oh no? I have Ad-Aware SE Professional, which is good enough, but I wouldn't consider it a firewall. It doesn't check what is connecting to your computer, etc. Would you mind telling me what's wrong with not having a firewall? I would really like to know.

Microsoft Anti Spyware~

I've heard that's pretty good.

Valid answer:  Your system did not reply to the UDP test messages received from the Battle.net server.  This can be caused by: badly configured router, firewall, or just it failed to send back, which you really cannot prevent.

If you're on Windows without a firewall, you're crazy.  Unless you know what ports are open and how to close them, you're constantly in danger.  Plus, anybody anywhere can log into your computer with a NULL account and look at shares, settings, who's logged on, and tons of other stuff.  There isn't really a way to stop that.

Anyway, back to the problem, UserLoser is mostly right.  It's because a UDP ping isn't getting back to Battle.net.  There can be lots of causes, like he said.  However, whatever is causing it can be fixed.

What kind of network do you have? Is it a single computer connected to the Internet, or are you behind a router?

And @DeTaiLs [totally off-topic]: Jesus, learn some English.. it hurts to read your posts.

I think the error was just something that randomly happened. It worked correctly right after reconnecting. Anyways, yes I am on a router. I don't think a firewall is necessary unless you're going to be doing unsafe things online (downloading trojaned files, etc.). If anyone can easily log into my computer (ok, maybe not easily) then why hasn't it happened before while I was firewallless?

Most routers have a firewall built in. So you are behind a firewall.

[quote author=iago link=topic=11353.msg109448#msg109448 date=1114193529]
If you're on Windows without a firewall, you're crazy.  Unless you know what ports are open and how to close them, you're constantly in danger.  Plus, anybody anywhere can log into your computer with a NULL account and look at shares, settings, who's logged on, and tons of other stuff.  There isn't really a way to stop that.
[/quote]

Psh.  I'm on Windows without a firewall.  :P  According to Norton Internet Security 2005 (on the other Windows installation that DOES have a firewall), I have no problems anywhere on my computer.

My hardware firewall is configured so that this machine is DMZ.  :)

Shout - Firewalls and Routers aren't the same thing.  But routers are usually good enough.

MyndFyre - that's a risk I wouldn't want to take, personally.  There are so many things that can be done to an unprotected windows box (like I said, look up null sessions), and even if they're protected I'd worry about new viruses/worms.

IMO, the probable error was in the link he posted: your connection is poor. If you live on the other side of the world, the UDP response may not have reached it in time.

Back in probably like 1999 or so, I was still on dial-up, and I used to get the in-game UDP on starcraft about one of every say 15 times I tried connecting or so.  It's nothing wonderous, just wait a few minutes and reconnect  :o