Network Settings
iChat In Pictures >> You are in Folder
7_System_Prefs-Network >> Page: TCP Tab
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4[4] |
4 iChat Network TCP tab |
02-10-2006 |
The TCP tab for the Chosen Network
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OK this is where we are aiming for with this series.
Why ?
This set of pictures is mainly to do with page 3 of the main part of the website. It is very important for iChat that your home Network is set out to be as linear as possible with no over lapping subnets works created by having two devices acting as DHCP Servers.
The Picture
So in here you can look up how you are getting an IP, whether it is via DHCP or Manually (Apple's Name for Static Routing). What that IP is, What device is apparently the "Router" or at least what IP it has which should tell you something when used in a Web Browser.
Somewhat hidden by my overlaid arrows is the fact that the TCP/IP is the Active blue one. In some displays like Airport this is not the first tab and you have to select it. Also depending which tab you were on the last time you were in Network, that might be the tab. Basically, select the TCP/IP tab to be the front one.
The first red arrow points out that I am set to "Manually" (the Mac's name for Static Routing).
Yours may say "Using DHCP" as this is the default setting for a Mac. It presumes your Modem or Router that you are connected to is issuing DHCP IP addresses. Suffice it to say that the next two red arrows will point to the same information as to your own IP and that of your Connection device (labelled "Router" here).
Now the green set of arrows. These point to the Subnet Mask and DNS servers. Whilst your set up says Using DHCP you should make a note of these if you are going to set up Static (Manually) routing. This is addition to the "router" IP. You will have to type the information into the relevant text fields (as they are shown here).
Essentially if setting up Static routing and turning off the DHCP server in the device you are connected to the DNS, Subnet Mask and "router" IP are going to be the same. You could, as I have done here, use the same IP for the computer. As this "router" is at 192.168.1.1 I could use any from 192.168.1.2 - 192.168.1.255
Anyway this is the Preference Pane to look at all this Stuff
A word on the DNS server Box. The display shows two DNS servers. You type one and then hit the enter/return key, then type the next. It is possible to list as many as you want, but the other will be out of sight. Scrolling does not work here and you have to use the Up and Down arrows to check if the list is longer.
Summary
iChat is an app that pushes data to a Specific Set of ports at a specific Location (IP address)
TCP/IP is the way it is done as it helps note the route of the packets of Data over the internet and also back to your computer.
Your Modem gets an IP from your ISP (Internet Service Provider).
IP addresses are like postal addresses. They come in 4 sets of 3 digits although leading zeros are often missed off.
Your Router whether that is a dual action Modem/Router or a separate device then passes the data to an IP on the Local Area Network (LAN)
Some IP addresses are reserved for what is refered to as Private IP addresses. They are in three Sets
- 10.0.0.0 through to 10.255.255.255 or 16,777,216 addresses
- 172.16.0.0 through to 172.31.255.255 or 1,048,576 addresses
- and 192.168.0.0 through to 192.168.255.255 or just 65,536 addresses
The smallest of these is still going to be enough for most Home Use set ups
A subnet is the last set of 0-255 such as 192.168.0.0 through to 192.168.0.255 or 256 Addresses.
So a Home LAN is likely to a subnet of just 256 Addresses.
If your Modem can route it might have limited physical ports to plug Ethernet Cable into and you may also have iPhones or Wifi Only devices that need connecting. Most people add a Wifi Cable Router. The default setting for many is that they act as the DHCP Server (Dynamic Host Configuration Protocol).
This means your computer can be getting two IP addresses from two Subnets (It will only display one though) an confusion ensues and iChat's Connection Doctor will look a complete mess.
Some routing but Non Modem devices can often be set to be an Access Point (Or Slave) to and main routing device.
Setting the computer to use a Static Address means it will keep the IP address even if switched Off at times. ON the Routing device turing Off DHCP means only the allocated IP addresses can be used (Meaning you are not broadcasting to all and sundry).
Some routing devices let you set up Mixed IPs, some fixed (Manual) and some DHCP for iPads and iPhones that can't do Static/fixed IPs and in some cases limiting the number of IPs in use overall.
If you are going to go Static/Manual/Fixed then you will need some of the info here when it is getting a DHCP issued address. THe DNS server info (servers that convert IP address to Names on the internet) the Subnet Mask (Fine tunes the addressing in the Subnet ) and of course the IP the routing device is at.
As we need to open ports in the Firewall on the Mac if it is On then the same Applies to the Modem/Router device(s) as some can only open ports using the Port Forwarding method that points the Ports at one IP - which then will not work if the compuetr changes it's IP every now and then
Next:- Modem and Routers
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