Some whois services are better than other. A good one is at DomainTools:

http://whois.domaintools.com/ 

You can use this by just sticking the IP address you want to check on the end of the URL. For example:

http://whois.domaintools.com/212.58.250.36

Setting up Windows Remote Desktop to allow you to use another machine on the same local network is very straightforward. Getting a Remote Desktop connection to a PC on a private external network is a little more tricky. I use PuTTY to SSH to the gateway machine at work.

Part of the PuTTY session is a series tunnels from ports on my local machine to ports on machines on the remote desktop. One of these is a mapping from the localhost port 3389 to port 3389 on a machine at work. Port 3389 is the port used by Remote Desktop, so this tunnel should mean that, once PuTTY has connected me to the external network, I can Remote Desktop to localhost and I will, as if by magic, get the login prompt for the remote machine.

However, having copied back into PuTTY the sessions from my previous Windows installation*, when I connected to the remote machine and then did a Remote Desktop to localhost I got the error message: "The client could not connect. You are already connected to the console of this computer. A new console session cannot be established."

The reason for this, it turns out, is that Remote Desktop knows it shouldn't allow circular connections: from this computer to this computer. So it rejects attempts to connect to 127.0.0.1. Now, as localhost resolves to 127.0.0.1, this gets rejected also.

However, on Windows, all other IP addresses in the 127.x.x.x range also represent the local machine, and Remote Desktop does not block these addresses. So this allows you to map port 3389 on one of these addresses (e.g. 127.0.0.2 or 127.254.254.254) to port 3389 on a remote PC and then you can specify that address in the Remote Desktop login window.

Note: Although the Source port field is clearly intended just for a port number, you can also put an IP address in there, followed by a port number - for example, 127.254.254.254:3389 - and then the remote IP address or hostname, followed by the port number, in the Destination field.

* The PuTTY sessions for each Windows user are stored in the Windows registry in:

HKEY_USERS > [GUID for user] > Software > SimonTatham

Before reinstalling Windows I'd exported the whole registry to a .reg file on my network drive. To put the details into the new registry all I had to do was open up the .reg file in a text editor, save it with a name like putty.reg on the desktop of the target PC, delete everything in the file after the first line up to the start of the HKEY_USERS > [GUID for user] > Software > SimonTatham section and everything after that section, then save it again. Then you just need to right-click the icon on the desktop and choose Merge.

Dan's Guardian is a content filtering service that can be installed as an add-on to SmoothWall. I have SmoothWall running on an old PC, behind my Sky router, as an always-on firewall for my home network. Because I have two kids, I want to filter Internet content and Dan's Guardian does a pretty good job of this. I like it because it's very configurable and allows me to determine the level of filtering, specific sites or domains to block, exceptions to filtering, types of files to block and so on. However, Dan's Guardian relies on transparent Web proxying being enabled, so I need to have that turned on:

Anyway, I couldn't figure out what the problem was until I eventually found a page on the SmoothWall Support site called "Using ident on Windows XP - common problems", which says:

Ident is a service running on port 113 and as such, port 113 needs to be opened on the workstations, in order for ident to be able to server the username. If the built-in firewall is enabled on any Windows operating system, it needs to be configured to allow access to port 113. This can be done using a log-in script or by manually configuring the Windows firewall software. Please refer to the Windows documentation for information on how to do this.

And then a lightbulb went on and I remembered that I'd previously had Windows Firewall turned off. Sure enough turning it off again solves the problem and lets me access the Internet via the transparent proxy. But, as the quote describes, you can run Windows Firewall so long as you add port 113 as an exception. To do this, go to Control Panel, open up Windows Firewall, click the Exceptions tab:

Click the Add Port button and add port 113, with a description:

The solution:
FileZilla - but you need to know the recipe of the secret sauce!

I started by installing Windows own FTP server (an extra Windows component that you can add via Add/Remove Programs). I then enabled this in the IIS Manager. However, the problem I got was that, although I could FTP to the server I couldn't save anything, do an ls or a pwd or anything useful.

So plan 2, after disabling Windows FTP, was to use FileZilla. This is an open source FTP/SCP project and you can download server and client software here:

http://filezilla-project.org/

However, I'd recently installed Apache/PHP/MySQL using the very wonderful XAMPP (see XAMPP - Web server + MySQL in minutes), so I already had FileZilla, I just hadn't enabled it. I did so and everything seemed to work except that when I FTPed to the machine as any user, with a legitimate password I'd get a "530 Login or password incorrect" message:

C:\Documents and Settings\ac>ftp showcase.memex.co.uk
Connected to showcase.memex.co.uk.
220-FileZilla Server version 0.9.23 beta
220-written by Tim Kosse (Tim.Kosse@gmx.de)
220 Please visit http://sourceforge.net/projects/filezilla/
User (myserver.myorg.co.uk:(none)): Administrator
331 Password required for administrator
Password:
530 Login or password incorrect!
Login failed.

The secret is that you have to go into the Admin program for FileZilla and add users/groups in there, specifically assigning each access to parts of the file system and defining what they can do (e.g. read, write, etc).

With XAMPP this is easy. From the XAMPP Control Panel, click Admin for FileZilla:

Enter the Administrator password:

Create groups with the appropriate access rights. Then create users and assign them to a group:

Now you can open up a command console on a remote machine, enter ftp servername and log in to the server to put/get files as required.

My set up looks like this:

I have the 2 old PCs (firewall and web server) tucked away in a cupboard where they sit, ticking over, without monitors, keyboard or mice. However, the firewall machine starting making a noise so I took it out to investigate. The noise was a combination of the hard disk and a little fan on the CPU heatsink. Unfortunately the PC was obviously on its last legs because having moved it around, opened it up, poked and prodded it, something gave up and it went from not booting up Smoothwall to not booting at all. I had power but no other signs of life.

To cut a long story short, I bought a new firewall machine off eBay. £35 for a Compaq Deskpro in a little mini case with a PIII 533MHz processor, 128MB of memory and a 10GB hard disk. The price included free delivery. The only things wrong with it were a broken power switch button and a dodgey CD. The power switch wasn't an issue, you just had to take the case off to start it, but as it's going to be on 24/7, and it's set to reboot if the power fails, that's fine. The CD drive was more of a problem. Because it's massively over-specked to be a Smoothwall machine I thought I'd swap it and the web server, but the intermittant CD drive caused me hours of grief trying to install Fedora, so in the end I gave up, opted for the easy solution and just installed Smoothwall instead.

Installing Smoothwall Express is a cinch, so once I'd decided to just replace the broken machine with the new one I was back up and running in no time.

Check out Smoothwall at www.smoothwall.org.

A wireless access point allows you to add wireless connections to your existing wired network. It differs from a wireless router, which you'd typically use if your whole network was wireless (e.g. positioned between your computers and the broadband modem) and which usually includes firewall software.

My network consists of 5 computers:

• an old PC that serves as a gateway firewall
• another old PC, running Fedora Core 3, which is actually on its own "DMZ" network and acts as a web server (hosting this web site)
• my main desktop PC, running XP
• another desktop PC, also running XP
• my laptop, running Windows 2000

The wireless access point simply allows me to replace a length of Ethernet cable with the WAP at one end and the wireless network card at the other.

The Linksys WAP54G is a 802.11g machine that allows data transfer rates of up to 54Mbps. It comes with a CD and a configuration utility that makes setup a cinch. You can be up and using it in no time at all - and I was. The trouble is that the default setup has no security. It's completely wide open, so anyone in the vicinity can connect to your network. Linksys obviously wanted to make getting started as easy as possible, but turning on the security features of the WAP54G are less obvious.

If you read the User Guide you find out that you can configure the WAP54G via its web interface, by browsing to 192.168.1.245. However, when I tried this I could get a web page. The problem is that if your network is not in the 192.168.1.x range, you won't be able to access the web interface. This is the bit they don't tell you.

The solution is to temporarily take your computer (in my case my laptop) off the network, change its IP address to something in the 192.168.1.x range and connect it directly to the WAP54G using a network cable.

Doing this involved the following:

1. Taking out the new wireless network card and replacing it with the old Ethernet card.
2. Changing the IP address of the laptop from a dynamically assigned address to a static address in the 192.168.1.x range (see below for details of how to do this in Windows 2000 and XP).
3. Connecting the laptop to the wireless access point. Note: with the WAP54G you can use a normal patch cable, you don't need to use a crossover cable as you normally do for connecting computers peer-to-peer (see below).

Once I'd connected directly to the wireless access point using a computer with an IP address in the correct range (I chose 192.168.1.246) I could browse to http://192.168.1.245, log in using no user name and the password "admin" and then go through the process of turning off SSID broadcast, changing the password, changing the channel number and enabling encryption.

Note: Each time you apply a change the WAP becomes temporily unavailable, the browser will be unable to find the web page and your PC/laptop will tell you that the network cable has been unplugged. However, the connection will be reestablished after a few seconds. If you refresh the browser, the web interface will reappear.

In my case I wanted to change the IP address of the wireless access point, so that I could access it from computers with IP addresses in the address range of my network. If you need to do this, you should only change the IP address and gateway address of the wireless access point as the last thing you do, as you won't be able to reconnect from the computer in the 192.168.1.x range once you've done this. You'll have to change the IP address of your PC/laptop before you can access the configuration page again.

If, while configuring the WAP you managed to lock yourself out of it, reset it to its factory settings by pressing and holding the Reset button on the back of the WAP for about 10 seconds. Then start the configuration process over again.

Once I'd done this, I disconnected my laptop, shut it down, put the wireless network card back in, booted up and then changed the IP address back to its original, statically assigned value. I then changed the profile of the wireless network card, choosing the same encryption I'd set up in the WAP's encryption config page. I browsed back to the config page and set up MAC address filtering, specifying the MAC address of the wireless network card in my laptop (see below).

Changing the IP address of your computer

Windows 2000

1. xxxxxxx
2. xxxxxxx

Windows XP

1. xxxxxxx
2. xxxxxxx

Crossover vs straight-through network cables

Your standard network "patch" cable is a length of Cat 5 cable with an RJ-45 connector on either end. Simple as that. This is a straight-through cable. The wires connect the pins at one end to the matching pins at the other end, just as you'd expect.

However, if you want to use a cable to connect one computer directly to another (peer-to-peer), this cable will not work. The problem is that two of the wires need to be crossed over, so that the wire from the transmit pin on one end goes to the receive pin on the other end, and vice versa. If you don't do this, your transmitting to a transmitting pin and receiving from a receiving pin. Normally this swap over takes place in a hub or a switch, which is the usual situation: several computers connected together via a switch.

So, what you need to connect two computer directly is a crossover cable. It looks just like any other network cable, but it's not, so keep it separate and put a tag on it or, sooner or later, you'll cause yourself grief when you spend an hour trying to figure out why you can't connect a machine to your network before you remember you've gone and used the crossover cable to connect the machine to the switch.

Finding the MAC address

The Media Access Control address is a series of 6 two-digit hexadecimal numbers that uniquely identifies a network card. It's a hardware thing, so if you change network cards you get a new MAC address. To find the MAC address go to Start > Run, enter "cmd" (without the quotes) and click OK. In the console window, enter ipconfig/all. The MAC address is listed as the "Physical Address".