Network Firewalls

The friendly things, that make a developer's life a nightmare, but your customers safe and happy.

The first things that I really discovered, was that I could not ping the PC i wanted to use as the client.

It seems like an easy thing to do, just install the Sun Java Application server on XP, enable the samples server port and then goto another PC and browser over to the server.

After that, I could really start testing out my work on java servlets. And, then eventually move on to do more work on getting a JSP / Servlets certification study done (well at least started :-))

When the Sun application server was working, and the Hello JSP deployed so easily, I thought I was in heaven, or at least had justified leaving Las Vegas early, missing out on the 25 cent craps tables in my favorite casino and driving through an unexpected snow blizzard (with police escort).

Then it happened. I could get to the apache server via the localhost method, and I could use the local IP of the computer, well laptop, to see my achievement. But when I went to the other computer, also a laptop, it did not even see anything.

Both computers worked fine out to the internet, and both could ping the router.

Then the server computer could ping everything and everybody, except the client computer I wanted to use.

Being a great hardware guy, actually down to the sub-chip level, I decided that maybe my network TCP/IP was a bit fuzzy so a re-cabled down to the bear bones and put in static IPs, just to know that everything was as I expected. It would be annoying to get errors just because the DHCP server dropped the lease from time to time.

Well, everything still worked, excepted the ping.

It was really crazy, because the client could ping the server, but the client could not even ping itself? That was odd.

First we blame Bill, then we think about. This time, I thought about the service paks. And, finally about the new firewall for XP that I wanted to use.

FIREWALL 

After searching around, I finally remembered that after going through all the trouble of installing the service pak for this feature, I had brought a new laptop that came with Norton Anti-Virus. Which also had a FIREWALL package included.

The firewall does not know from internet to intranet to local net, so it decided to protect me from everything. I discovered this tidbit, after I checked by 2 week old wireless router for mis-configurations and the like.

So, disable your local firewall in your Anit-Virus package when you first start setting the apache server up on your Windows network!

Discard Local Ping Packets

The specific thing that you want to dis-able is Discard Local Ping Packets.

You will be able to ping every body and their ancestors, but you will not be able to ping your own local IP!

The good news, "This firewalls tuff works."

The bad news, "This firewall stuff works!"

I have other firewall packages, so this is not a ding or recommendation for Norton / Symantic. It just happen to be what was on the client laptop I was using.

Life is simple and life is good, but it is 3am in the morning :-))