Home network harmony

Sharing the internet
Connecting to the internet is usually the easiest step on the road to network harmony. This is mainly because the PCs and other devices on your Lan don’t need to talk to each other for that to happen. They just need to be able to find your network router. And for that all they need is an Internet Protocol (IP) address that will allow them to send and receive data over the Lan, plus the IP address of the default gateway (the router that’s connected to the internet) to get out onto the web.

In the bad old days that meant manually configuring all your devices to use addresses on the same subnet, such as 192.168.0.xxx or one of the other ranges reserved for private use. Thankfully, most routers now come with a built-in DHCP server that makes light work of the task.

Short for Dynamic Host Configuration Protocol, a DHCP server hands out network (IP) addresses to any device that requests one. It makes sure that each address is unique and on the same subnet while at the same time also telling the device the address of the default gateway.

Very little setup work is required as on most home networks the default settings used by the DHCP server will be fine as they are. And there’s very little to do at the client end either as most PCs and other devices will already be configured to get their addresses automatically via DHCP and, if they’re not, switching is rarely more than a tickbox option in the device’s network settings menu.

Addressing issues
For the most part DHCP just works, but problems can arise and it’s worth knowing how to troubleshoot them. On a Windows PC, for example, you can see what IP addresses have been assigned to devices on the network by opening a command window (Start/Run/cmd.exe) and typing ‘ipconfig/all’ at the prompt (see screen, left). On Linux the command is ifconfig, although you may need suitable administrative rights to get it to work (type ‘ifconfig/help’ to see the options available). Otherwise there will usually be some kind of network utility in the device’s user interface to show you the current network status.

If the address doesn’t match others on the network the device may have been configured manually, so just change it to automatic addressing. If there’s still no address then the device concerned hasn’t been able to find the DHCP server. Some Windows PCs generate an internal IP address themselves (in the format 169.xxx.xxx.xxx) when that happens. And that can be because either the device or the router (or both) have become disconnected from the network, or the router running the DHCP server has crashed or been switched off. All of which are relatively easy to check and fix.

Sharing files
Unfortunately sharing files and troubleshooting sharing problems is rarely as easy as connecting to the internet, even if all your computers are running the same operating system. Mix different platforms together and it can get even harder.

Some issues are easy to avoid, such as making sure all the computers on your network are in the same network workgroup. Windows XP Professional and Vista, for example, both use ‘WORKGROUP’ as the default name, but on XP Home it’s ‘MSHOME’. Similarly, Linux may be configured to use something else entirely, depending on the particular distribution you’re using. Make sure you use just one workgroup name, possibly changing everything to be in a workgroup of your own choosing to avoid errors.

Simply specifying the wrong workgroup name shouldn’t stop you browsing the network, or accessing shared resources such as printers. You’ll just see more than one workgroup when you start to browse the Lan.

If you can’t see other network systems or can’t connect to particular shared directories, the first thing to look at is the local software firewall. With the latest XP service packs (SP2 and SP3) the Windows firewall should allow file sh aring protocols through automatically whenever file sharing has been turned on, but that’s not always the case so it’s worth checking. You might also try turning all local firewalls off, albeit temporarily, to see if that fixes the problems, then look at changing their configuration to enable them to be turned back on.