Showing posts with label networking. Show all posts
Showing posts with label networking. Show all posts

Saturday, 16 July 2005

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Home networking is child's play

Low-end, though perfectly adequate, computers are so cheap these days it's feasible for each member of the household to have their own, dramatically reducing incidences of arguing, hair pulling and death threats.

Even so, shelling out for one-off hardware purchases is only the beginning - everyone will want to have unfettered access to the internet, and this is where your running costs can truly begin to spiral if you're not prudent. Only a few years ago, making this a reality would have involved having a separate phone line installed, and setting up individual ISP accounts, for each computer.

Not any longer! This being the age of inexpensive broadband, it makes sense to do away with personal net access in favour of sharing a high-speed connection via a single ADSL-enabled phone line. See, there's a communist in all of us if you look close enough!

You'll need to splash out on some more kit - a router and several network interface cards (NICs) / network adaptors - but don't worry, these will pay for themselves in no time at all. If you already have a modem you may like to save some money by buying a stand-alone router. On the other hand, if you haven't yet taken the broadband plunge, you'd be better off getting a combined modem-router unit. Actually this is recommended either way since most ISP-supplied modems are of the more troublesome USB variety, while a good modem-router box will be ethernet-based. Ethernet-based routers are more robust, partly because they do not require the installation of drivers.

As strange as it may seem, security experts advocate the use of a router even for independent, non-networked computers. This is because they come equipped with a sturdy, built-in, hardware firewall which cannot be remotely disabled by hackers, unlike flimsy, largely superfluous software equivalents such as Zone Alarm. Sorry to shatter any cosy illusions of online safety you may have invested in such protection mechanisms, but they are practically useless - the first task any self-respecting trojan or virus will perform is to shutdown your software firewall.

Routers can be either wired, wireless, or both. Whichever type you settle on you will need to equip each computer in your network with either an internal PCI network card or a USB network adaptor. Taking the internal route is more efficient as NICs communicate with the router without hogging a precious USB port. The USB adaptor method is ideal for people who aren't comfortable tinkering with their computer's innards (or can't because they are laptop or Mac Mini users) or who regularly transfer network connectivity between different systems. PCI network cards can be hooked up to both wired and wireless networks (some are outfitted with an ethernet port, others have an antenna, some have both). Most USB adaptors are designed only to provide wireless support, though it is possible to purchase USB ethernet adaptors which mimic the modus operandi of wired NICs.

Wired networks are strung together via RJ45 network cable - one end is inserted into the ethernet port of your adapter while the other is inserted into one of your router's free LAN ports. Conversely, wireless nodes talk to one another via radio waves based on the 802.11a, 802.11b or 802.11g WLAN standard. Briefly, these differ in terms of transfer speed, wireless range and frequency, 802.11g (Super G even) being the most advanced to date. The precise specifications of each are detailed in this Speed Guide article.

What prompted me to write this post was getting my own home network established. My challenge was to provide high-speed internet access for two Dell PCs and a Mac Mini sharing a single ADSL internet account. Because the computers are situated in opposite corners of the house, up and downstairs, going wireless was the only sane option. I thoroughly researched a raft of viable solutions and came to the conclusion that the Netgear DG834GT router coupled with two Netgear WG111T USB adaptors was the best way to go (the fact that one adaptor came free with the router helped to swing my decision somewhat).

As the router requires no drivers, it can be considered 'platform-independent'. The USB adaptors do require drivers and only Windows ones are available. This meant that the router would have to be attached to the Mac. The router is connected to the Mini's ethernet port via a length of RJ45 network cable. Subsequently communication with my ISP is mediated via a phone cable - intercepted by a DSL filter - plugged into the phone socket. The broadband filter allows you to connect a phone and computer to the same line, use both simultaneously, and filter out the distortion introduced whenever a phone line is converted to accept broadband connections. Power is sourced via an adaptor plugged into a mains socket. Conveniently all these components are included as standard in the router kit.

The router is configured through a web page, located by entering a series of digits separated by dots known as an IP address (192.168.0.1 for Netgear and several other routers). There are many baffling ISP-specific settings the router needs to take into account before you can get onto the net, but luckily, if everything goes according to plan, these can be automatically detected. In my case the procedure executed flawlessly - impressive stuff! All I had to do was enter my ISP username and password and apply the changes.

Getting the two Dells online was just as simple. I installed the drivers, plugged in the USB adapters and they sniffed out the router pretty much by themselves. Providing you (initially at least) choose to broadcast the name (SSID) of your wireless network, your adaptors will automatically detect and connect to it. If for some reason your neighbour's wireless signal is stronger than yours, you could even find yourself 'borrowing' their bandwidth - assuming they haven't enabled their router's security features. Tapping into open wireless networks (knowingly or otherwise) is illegal in some countries so paying attention to the name of the network you are joining is advisable.

Once you have established a connection to the net, to prevent other people piggybacking your internet account, getting up to no good and leaving you to face the consequences, you must take the time to lock down your network. The first thing you should do is enable 'access control'. This allows you to selectively permit access to your router by specifying the MAC (Media Access Control) addresses of your USB adaptors/NICs. These are simply serial numbers used to identify each node in a network.

Having determined that each computer in your network is on good speaking terms with your router, it is also recommended that you disable SSID broadcasting. This prevents snoopers from automatically detecting your signal and exploiting your resources, advancing their nefarious schemes and whatnot. If you opt to obscure your internet access point in this way you will have to manually enter the SSID of your router into the configuration menu associated with each of your nodes.

Remember to change the default SSID - disabling SSID broadcasting is useless if anyone with half a brain can guess the name of your router!

While you're at it, remember to change your router's default password to prevent people from tampering with your settings, disabling your firewall and so on. Tip: use a random password generator to create a super-secure, long-winded, unguessable string of gibberish.
Changing your SSID and disabling SSID broadcasting does not provide uncrackable protection, however, will deter casual, amateur delinquents from throwing a spanner in the works.

More sophisticated security features I would urge you to take advantage of (or at least familiarise yourself with) include:-

WEP (Wired Equivalent Privacy)
WPA-PSK (Wi-Fi Protected Access Pre-Shared Key)
WPA-802.1x

Each of these techniques offers varying degrees of encryption for data transmitted over radio waves.
WEP is a first-generation wireless security mechanism which has been rendered worthless by the widespread availability of idiot-proof hacking tools. Don't give it the time of day.

Second-generation WPA wireless protection is much more dependable. It comes in two flavours; PSK for home users and 802.1x for larger scale business deployments. All you really need to know is that by generating a string of ASCII gibberish between 8 and 63 characters long and saving them in your router's control panel you can protect yourself from the most dedicated eavesdroppers. Again, use a random password generator to ensure your WLAN is super-secure. Don't forget to enter the same key in the security control panel of each node before attempting to connect to your newly locked down network. That'll be why it's called a 'pre-shared key' then. Clever!

802.1x won't be of much interest to you unless you're a network manager or ISP administrator. Even if you wanted to employ this higher grade authentication system on your home network, you'd be out of luck unless you happened to have a spare 'RADIUS' (remote authentication dial-in user service) server kicking around. Checked the closet? None to be found? OK, let's move on.

Of course if your router supports both wired and wireless connections, but you only intend to use it as a wired base station, you can bypass all of the above by simply disabling your router's WAP (wireless access point) capability. Wired networks are inherently more secure than wireless ones, though are nowhere near as versatile. For instance, connecting your laptop to your network via a 100m coil of network cable so it can be used out in the garden isn't exactly ideal. Similarly, lugging about a cable so you can plug your laptop into Starbuck's network isn't very practical either - do they even support that?

Whoa horsy, now there's a wacky phenomenon. Personally I've never understood the attraction of public, mobile computing. How are you supposed to get any work done when you're forever looking over your shoulder to check if anyone is approaching you with a swag bag? If conveying some piece of information or other is so earth-shatteringly critical to their continued existence people feel compelled to setup their office in a coffee shop and go online on route to their high-faluting business meeting, why wouldn't they simply use their mobile?

Then you've got the ones who's world won't crumble if they don't send someone an email there and then while they slurp their overpriced Slopuccino, yet somehow feel it necessary to surf the web for, oh I don't know, to shop for new sandals. It won't kill you to detach yourself from the net while you take a fifteen minute break you know! You may miss the opportunity to be the first person to comment on Slashdot's latest 'hamster learns UNIX' exclusive, but believe me, you'll survive.
Even Bill Gates takes time out to reacquaint himself with reality from time to time. He uses his downtime to whip the army of Filipino children enslaved in the rat infested Microsoft dungeons, but you get my point.

I'm convinced the only people who sit in coffee shops and McDonald's 'restaurants' tapping away on their laptops are either models posing for hi-tech magazine photo shoots, or exhibitionists who want the world to know they've just bought a top-of-the-line Sony XZS569 laptop with built-in plasma screen and dishwasher.

Phew! That rant has been brewing for a while. I feel much better having got it off my chest. Now where were we?

With the preliminaries taken care of, you may like to setup a shared drive or enable remote access to a printer. To share a printer, open the 'printers' window from within your control panel and right-click on the icon representing the printer you wish to share. Now select 'share this printer' and when the printer's properties dialog box puts in an appearance, select the 'sharing' tab. From this menu click on 'share name', enter an appropriate moniker and OK your decision.

To send data to your new network printer from a remote computer you would add a new printer in the usual way, but rather than selecting a local device you would browse the network for connected printers and select the one you've just elected to share.

Sharing folders is just as simple. You would locate the folder or drive you wish to make available, right-click on it and select 'sharing and security'. From within the 'sharing' tab you would opt to 'share this folder'. You are given the option to name the shared folder or drive at this juncture - whatever you enter will be used to identify this area of the hard drive within your network, without actually changing the label on the host system.

See, child's play like I said. I accomplished all that without an MCSE certificate, or safety net! I can tell you, I felt pretty silly cancelling two dial-up ISP accounts online and ringing up BT to arrange for two phone lines to be disconnected. Wireless networking wasn't invented last week, but until now I've been too busy watching knee-slappingly frolicsome movie clips of dolphins getting hit in the crotch with a football to make the transition.

Friday, 24 May 2002

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How do I find out if my IP address is static or dynamic?

Having this information to hand is especially useful if you intend to set your computer up as a web or FTP server. If you've got a static IP address you can redirect your domain name to point to your own computer instead of a remote host to enable people to access your data or web site. This can also be achieved with a dynamic IP address, but it's a bit more fiddly.

There are various ways of identifying your IP address, but I find the easiest method is to use IP Agent, available from the Gibson Research Corporation (click on the 'Shields Up' button, proceed to the freeware section and then click on the download link near the top of the page). You'll need a microscope to see this program as it's absolutely tiny - no bloatware here folks!

Once downloaded, if you simply double-click on the program's icon you will find that your IP address is staring you in the face - no searching through menus is required - that's all there is to it.

If you make a note of this number, disconnect from the net and then reconnect you can see whether or not you have been assigned with a new number.

Monday, 30 July 2001

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Houston, we have a (file transfer) problem

Common wisdom and research conducted by the Bureau of Made-up Statistics suggests that the best way to introduce a web tutorial is to impart a well-meaning, but overly patronizing metaphor. Let's give it a whirl then shall we. How's this? The internet can be thought of as a giant, digital take-away. It's brimming with tasty dishes for you to consume, but sampling them isn't quite as straightforward as dialling a phone number and getting the delivery man to bring them to your door.

As already noted in my 'essential applications' tutorial, the most efficient way to get your 'orders' from A to B is to employ a download manager. But which one to choose? If you're a PC user I'd recommend Flashget, while Mac people would be well-advised to use Folx.

With either of these applications installed, whenever you click on a file, the browser integration gizmo will kick into action and a download window will appear stating the file size, file location and estimated transfer rate of your chosen download. If everything goes according to plan you should simply be able to click on the 'download now' button and your download manager will take care of the rest.

This process can be repeated for a well-nigh infinite number of transfers - you do not have to wait for one file to finish downloading before clicking on the next one you wish to transfer. Each new file will be added to your download queue and transferred sequentially in the order they were clicked - unless of course you choose to rearrange them in order of priority. Once your download manager commences transferring a series of files you can close the web page where you found them and take your metaphorical surf board elsewhere. No more internet babysitting, hoorah!

It's all gone Pete Tong

At this stage there are oodles of snivelling error messages you may be confronted with. In determining the reason for the inaccessibility of a particular file some download managers are more informative than others. If yours ambiguously concludes that if a file cannot be downloaded it must simply be 'busy', it's time to switch to a more insightful application. Below you will find a list of some of the most commonly experienced file transfer errors, and possible workarounds for the non-fatal ones...

~ "File not found" - The file has either been deleted from the server, moved or was incorrectly linked from the outset by the webmaster. It could also be that the web space provider has zapped the file because its presence infringes copyright regulations as detailed in their terms and agreements of use tome. If you're confronted with this message it is probably best to look elsewhere for the same file - perhaps by prompting your download manager to search a variety of mirror servers or by manually scouring File Mirrors.

~ "Unable to connect to..." - You are most likely to see this message if the file you are attempting to download is stored on an FTP site. The explanation - FTPs are actually people's hard drives, which you can access only when their owners are connected to the internet. If you cannot get the file first time, just try again later. If this is happening frequently, the IP address may have been a temporary one and no longer refers to the location where the desired file resides (some ISPs will assign you with a new number each time you log on). The moral of this story is to download goodies from these sites as quickly as possible because they often have a short shelf life.

~ "Too many users - try again later" - Exactly what it says on the tin. The number of simultaneous connections permitted by many FTP sites is limited to a pre-determined maximum to keep download speeds to a reasonable level. Whenever this happens you will have to learn to be patient until it's your turn to connect. Do not 'hammer' the site (repeatedly try to access it) as this can annoy the owner who can then ban you from using it.

Another handy hint: if you've been banned, you will be abruptly disconnected from the FTP site without explanation whenever you try to log on - if you do not have a static IP address you can circumvent this dilemma by disconnecting from the internet and re-dialling. When you re-connect you will be allocated with a new IP address which will mimic the appearance of a new user the next time you try to access the FTP site.

To make sure this doesn't happen again, open your FTP client's options menu and extend the retry intervals to match the level deemed acceptable by the FTP sys op; anything above 20-ish seconds is reasonable. A better idea perhaps would be to schedule your downloads for a time when fewer users are likely to be accessing the FTP site - early in the morning (UK time) for example, when all the net-hogging American's are fast asleep.

~ "Incorrect password/username/access denied" - The owner is fed up with having hundreds of people clogging up his or her FTP site and has changed the password to prevent you from gaining access. This is very common where 'banner FTP sites' are concerned - those requiring you to click on various banners and hunt for keywords, which form the username and password necessary to access the server. Unsurprisingly this is another money making scheme - these sites are more likely to stay active as the owner has more to gain from keeping them up and running.

~ "Insufficient credits" - You are likely to see a message like this if you are accessing a 'ratio site' - one which requires you to upload a certain quantity of bytes before permitting you to download any of the hosted material. To solve this problem you can instruct your FTP client to begin uploading files whenever you are approaching the designated data transfer limit. This can be arranged simply by placing the files you wish to upload at the bottom of the list of currently downloading files. When you run out of credits they will automatically be uploaded. Alternatively have two FTP sessions open at once - use one to upload and the other to download simultaneously (some sites will limit your access to one connection per IP address so this method will work only when multiple connections are permitted).

~ Servers running Windows NT 4.0 and below do not provide support for the resume function. If you are downloading a file from an unresumable server and the connection is reset you will have to start transferring the file again from scratch. It is best to avoid such files like the plague, especially if they are quite large, but if this isn't feasible, download them one at a time and make sure you do not surf the web simultaneously if you have a slow connection. This will allow you to maximise the bandwidth allocated to your currently downloading file whilst minimising the likelihood of any interference which could result in transfer interruptions.

~ If when you click on a link it appears as a 'cgi' or 'php' file in the transfer window, the file is either being protected by an anti-leech system or is subject to a file tracking setup (usually just for statistical purposes), making it very awkward to transfer using a download manager. The best way around this complication is to temporarily disable your download manager by holding down the shift button whilst you click on the file and wait to be redirected to the actual target file you wish to download (keep in mind that this will deny you the use of the resume function in many cases).

Similarly if you attempt to download a file expecting it to occupy 300mb and it appears in your download directory in a matter of seconds, you can safely assume that you've downloaded the code responsible for redirecting you to the download rather the download itself. There are ways of convincing your download manager to cooperate in downloading these files, but again, in most cases it is quicker and simpler to use the method described above. Some sites simply do not like download managers. Call it a personality clash if you like, but don't waste any more time trying to make the two 'talk' to each other.

~ Note that many more of the errors you will come across while attempting to access FTP sites will not be reported in plain English. In contrast to those listed above, the only clue as to the cause of the problem may be presented in the form of a three digit code, which must first be deciphered before you can attempt to remedy the problem.

Below you will find a comprehensive list of these error codes along with their explanations. Note that not all of these codes should be a cause for concern. Many of them will appear simply to keep you informed of the commands currently being executed to facilitate the transfer process.

100 - The requested action is being initiated, expect another reply before proceeding with a new command.
110 - Restart marker reply.
120 - Service ready in x minutes.
125 - Data connection already open, transfer starting.
150 - File status okay, about to open data connection.
200 - The requested action has been successfully completed.
200 - Command okay.
202 - Command not implemented, superfluous at this site.
211 - System status, or system help reply.
212 - Directory status.
213 - File status.
214 - Help message.
215 - Name system type. (Where name is an official system name from the list in the Assigned Numbers document.)
220 - Service ready for new user.
221 - Service closing control connection. Logged out if appropriate.
225 - Data connection open; no transfer in progress.
226 - Closing data connection. Requested file action successful.
227 - Entering Passive Mode.
230 - User logged in, proceed.
250 - Requested file action okay, completed.
257 - Pathname created.
300 - The command has been accepted, but the requested action is being held in abeyance, pending receipt of further information.
331 - User name okay, need password.
332 - Need account for login.
350 - Requested file action pending further information.
400 - The command was not accepted and the requested action did not take place, but the error condition is temporary and the action may be requested again.
421 - Service not available, closing control connection. This may be a reply to any command if the service knows it must shut down.
425 - Can't open data connection.
426 - Connection closed; transfer aborted.
450 - Requested file action not taken. File unavailable.
451 - Requested action aborted: local error in processing.
452 - Requested action not taken. Insufficient storage space in system.
500 - Series Codes: The command was not accepted and the requested action did not take place.
500 - Syntax error, command unrecognised. This may include errors such as command line too long. 501 - Syntax error in parameters or arguments.
502 - Command not implemented.
503 - Bad sequence of commands.
504 - Command not implemented for that parameter.
530 - Not logged in.
532 - Need account for storing files.
550 - Requested action not taken. File unavailable.
552 - Requested file action aborted. Exceeded storage allocation (for current directory or data set). 553 - Requested action not taken. File name not allowed.

Even double Dutch makes sense with a double Dutch to English translator!