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Troubleshooting Q&A - June 21, 2004

Let's Chat About Firewall Issues

If your browser is browsing and your e-mail is flowing, there's one logical reason why IRC may be refusing to chat. Plus, sharing a cable between two PCs — we have some good news and some bad news.

By Ron Pacchiano

Q. I have been using mIRC on my home PC for a few years. I find it to be an invaluable tool for keeping in touch with people and also find it to be a useful research tool. I just started working for a new company and thought that it would be useful for me to have access to my mIRC clients while at the office. So I tried to install mIRC on the PC at my office, but I just can't seem to get it to work. I believe I installed it correctly, but no matter what I try, it still won't connect to the mIRC service. My Internet access and e-mail all function fine, so I know it's not my connection. What am I missing?

A. To accurately solve these types of problems it is always helpful to send us as much information as possible. Some specific information about your network environment and perhaps a copy of any error messages you might have received would be helpful in solving this problem. In spite of this, though, I think that this problem is straightforward enough where I can offer you an explanation for your current difficulties.

Since you're using mIRC (which the Windows version of Internet Relay Chat) on your home PC, I think it's a safe bet that you installed it correctly at the office. Further, since you have access to the Web and e-mail, we can also rule out any problems with your Internet connection. This strongly implies to me that your company could be using a firewall to block the ports that mIRC makes use of when establishing a connection.

This wouldn't be an uncommon practice in a corporate environment. Many companies have strict firewall and security policies in place and seriously frown upon employees installing software on their workstations without first gaining authorization from the network administrator. An application like mIRC is typically blocked by the company firewall for a variety of reasons. In addition to being a potential security risk, applications like mIRC have a tendency to drain employee productivity levels. Not to mention the fact that mIRC has a reputation for hosting some pretty sexually explicate sites that could leave the company liable to a potential lawsuit.

However, if you could prove to your company's network administrator that you have a business need for the mIRC client and get permission from your manager to use it, then he might be willing to open up the necessary ports on the firewall for you. I say might because mIRC potential could use a very wide range of ports to take full advantage of it.

For starters, mIRC makes use of UDP port 113 for establishing your identity. Then you'll need to open up TCP ports 6660 - 6669. I believe that port 6667 is the one generally used, but to be safe you should probably open all of them. The area where your network administrator is undoubtedly going to have the biggest concern is regarding mIRC's DCC functions. To use this feature, ports 1024 -5000 will need to be configured to allow mIRC traffic to pass over it. If this is something he's willing to entertain, then he could find more detailed information on mIRC and its ports requirements at http://www.mirc.co.uk/help/proxies.html.

Once these ports have been resolved you should have no further trouble accessing mIRC on you office PC. Good luck!

Q. I have a cable modem Internet connection that is shared with two PCs. Both PCs are connected to the network via RJ-45 Ethernet cables. The cable modem is connected to a NetGear RP614 router. One of the computers is running Windows 2000 Professional. The other computer runs Windows XP Home Edition. This is the machine that is giving me a problem.

The Internet connection on my The Windows 2000 Professional PC is running just as well as it always has, yet for some reason when my Windows XP Home Edition PC goes to get on the Internet that same connection is extremely slow. Web pages can take almost a minute to load and occasionally time out. This behavior is consistent whether or not the other PC is also online.

Both PCs can ping each other and I can print over the network. I have uninstalled and re-installed the network adapters, the modem and the TCP/IP protocol. I tried upgrading the network drivers, but it hasn't changed anything. I even tired moving the slow PC to a different port on the hub hoping that it might just be a bad port. It wasn't. As a final act of desperation, I contacted my ISP and had it perform diagnostics on my cable connection and according to them everything checked out just fine.

The most frustrating thing is that this isn't a new configuration. I have had all of this equipment in place for almost a year now and everything worked fine. Any suggestions on what I could try next to resolve this problem would be greatly appreciated.

A. Well, I have good news and bad news for you. The good news is I don't think your problem has anything to do with your hardware or your network configuration. Just the fact that all of this hardware was purchased, installed and had been working for over a year pretty much rules it out. Now, could something have happen to the hardware to cause this? It's possible, but the odds are against it.

This brings us to the bad news. From the way you described it, to me, it sounds like it has more to do with a software incompatibility or resource/memory shortage. Unfortunately, trying to isolate exactly what that could be is extremely difficult and would be almost impossible for me to instruct you on with the space we have available here. Typically the cause of this type of problem usually comes down to identifying exactly when things started to go wrong. You'll usually find that this corresponds to a time when a new piece of software was installed, a driver was updated or a service pack was applied. The best way of preventing this in the future is to use a utility like Microsoft's System Restore before installing or updating anything on the PC.

With System Restore you can revert your system back to a previous good configuration in the event of a problem. System Restore monitors changes to the system and some application files, and it automatically creates easily identified recovery points. These are created daily and at the time of significant system events (such as when an application or driver is installed). You can also create and name your own restore points at any time.

While this might be helpful for you in the future, it does nothing for your immediate problem. This is where the real headache comes in. If you can't isolate when the situation changed the easiest thing for you to do would be to simply wipeout and redo your laptop with a clean installation of Windows XP Home Edition.

One of the problems I've discovered over the years with Windows-based computers is that they religiously have to be erased and redone on almost a yearly basis in order to keep them running at peak efficiency. You see, over time Windows becomes bloated with numerous utilities, applications, driver updates, security patches and so on. That bloat has a tendency make the system unstable. Regrettably, redoing the system is usually the only way to effectively rid you of these mysterious problems. It's unquestionably a hassle, but it will usually give you the best results.

The only other suggestion would be to thoroughly scan your system for viruses. The symptoms you described are definitely exhibiting virus-like behavior and at the very least is worth investigating. A few years ago I had a similar problem. For some reason, my server had slowed to a crawl. No matter what I did, I just couldn't seem to repair it. Then one day I was out with another technician and we were working on a client's mail server when I noticed that the symptoms it was displaying were identical to what I was experiencing. We soon discovered that this server was infected with a variant of the Code Red virus. Sure enough, when I got home that evening I scanned my server and discovered that it too was infected with Code Red. I downloaded and ran the virus removal utility and within minutes my server was back to normal. I hope this helps. Good Luck!


Use our feedback form to submit your questions on home or SOHO networking issues. We cannot guarantee to answer every question we get, but we’ll consider them all.



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