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Old 05-05-2013, 11:20 PM   #1
cromei
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Registered: May 2013
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Unable to access Linux server after swapping from ethernet to wireless router.


I have gone from a: T1->3COM router->Server->CISCO48 port gigabit router->Linksys EA6500 Wireless router to: Satellite Feed->Linksys EA6500 Wireless router->Server.

I can get to the inter net on some of my wireless desktops and not others BUT only one desktop can access the server. The server has two LAN cards in slots and one native LAN connection. I tried running the SAT feed straight to the Server's native connection but lost internet to my desktops.

Any thoughts on a configuration that would let me see both the internet and the server?

Thanks in advance,

Chris
 
Old 05-06-2013, 02:07 AM   #2
Erik_FL
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Make sure that the satellite is connected to the yellow Internet port on the router. The server and any other computers should be connected to the blue LAN ports (or use wireless). It is a common mistake to accidentally connect a blue LAN port to the broadband (in your case satellite). By doing that you essentially leave out the router and instead end up with just a switch. The result is usually intermittent access to the Internet and other computers.

Start with one computer connected to a LAN port on the router. Make sure that the LAN port is configured to obtain an IP address automatically. You should be able to access the router using a web browser by typing in the routers address. For example:

Code:
http://192.168.1.1
If you don't know your router's address, the easiest way to find that is to display information for the Ethernet interface from a Linux root shell prompt. Type in this command.

Code:
ifconfig
With only one Ethernet cable plugged in, you should only see one Ethernet interface that is "UP" and has an IP address. If you don't see any Ethernet interface that has an IP address then your Ethernet interface might not be set to obtain an IP address automatically. If no Ethernet interface is UP then you may have the cable connected incorrectly.

Next you want to find out the default gateway. That is usually the address of the router. Type in this command to display the routing table and the default gateway.

Code:
route
At that point you should know the address of your router (on your Local Area Network). Type the address in a web browser. Log in to the router. The default password is "admin". If you have trouble getting the router's logon page to display in your browser, unplug the satellite from the yellow port on the back of the router. Type the following address into your web browser.

Code:
http://www.linksyssmartwifi.com
If you still can't access your router, you might have to reset it to factory defaults. That will enable the DHCP server on the router and reset the password to the default.

After you can log on to your router, then make sure the satellite is connected to the yellow port on the router.

Check the router status using the web browser and make sure that it has an Internet connection. If it doesn't you may have to change the type of Internet connection. Based on your description of the problem, you probably need to set your Internet connection to use DHCP (or obtain an IP address automatically). Also, you probably have to disable (or not use) PPP or PPTP. Some satellite systems require 802.3 protocol. Your router might not support that. The manual wasn't very helpful when I tried to check for 802.3 support.

There is another gotcha that you might run into with satellite. It's possible that your satellite interface (or modem) has the same exact network address as your router. In that case everything will work great for the router and computers talking to the router until you connect the yellow Internet port to satellite. To tell if that's a problem you can connect one computer directly to the satellite. Let the computer automatically obtain an address from the satellite Internet. Use the "ifconfig" and "route" commands to find out the information for that Ethernet port. If it is the same network address as the router or very similar, then you may have to change the router's network address. For example, change the router to "192.168.2.1" or "192.168.55.1".

After you have the router configured and the yellow Internet port connected to the router, you should be able to see that the Internet connection status is good on the router's configuration pages. Verify that the Internet is working on the computer that is connected to the router. If that is working you should be able to add other computers.

To add other computers you need to make sure they are set to obtain an IP address automatically, or you need to manually assign them an IP address. If you manually assign addresses you should reserve them in the router's DHCP settings so that they aren't also assigned to some other computer. Even when a computer obtains an address automatically, you can reserve its address in the router's DHCP settings. That is helpful to make sure that a server always has the same IP address, for example.

After computers have obtained an IP address from the router or have been manually configured they should be able to access each other. You can use the "ping" command to test access to other computers. Use the "ipconfig" command first (on the other computer) to find out its IP address. That's also helpful to verify that each computer has an IP address. Here is an example of a ping command.

Code:
ping 192.168.1.12
Wireless adds a little bit more configuration that must be done before computers can obtain an IP address. You have to configure a name and passphrase for your wireless network. You configure those things on the router first. Then you connect to the wireless network from each computer, by selecting the network and entering the passphrase. You may also have to select the correct kind of encryption.

If you are having problems accessing wireless or accessing the Internet on more than one computer, the place to look is in the router settings. Go back to a computer that is directly connected to a LAN port and make sure that you can get to the router's login page. Look at the router's status. To use the "www.linksyssmartwifi.com" address to look at the router you must disconnect the yellow Internet port. It's better to use the actual address of the router since you can leave the yellow Internet port connected.

In order to access the Internet, computers have to also know the address of a Domain Name Server. That is usually the address of the router. The router's Internet connection should have the addresses of the real Domain Name Servers. You can see that by looking at the Internet connection status on the router's configuration pages.

If ping is working and the default gateway looks correct, you can test the name service from a computer using this command.

Code:
nslookup www.google.com
You should get back a list of all the IP addresses for GOOGLE. This is one of the last things to test because everything else has to be working in order for this to work. When you can ping the other computers and the router, you have the default gateway configured correctly and a good Internet connection (according to the router) then this should work. If you can't access the Internet, test with "nslookup". If "nslookup" fails, then check the Domain Name Server settings on the computer and the router.

You didn't really say what the server computer does. If it is just a file server then it does not need any special configuration other than setting up a permanently assigned address in the router's DHCP settings. To use the server as a Domain Name Server or router then you have to make other changes to the server, router and computers on the LAN.

If you have some other special configuration then post exactly how the satellite, router and other computers are connected. Post the IP addresses and routing tables from the computers ("ifconfig" and "route" commands). If you don't see the Ethernet devices you expect with "ifconfig" use "ifconfig -a".
 
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Old 05-06-2013, 03:16 AM   #3
cromei
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Registered: May 2013
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That was an amazing answer, thank you. I have done all you suggested and all desktops are accessing the internet perfectly. Now I to bring the LINUX server online, previously it handled DHCP duties, I think all I need it to do now is be a file server that we all can access.
You said:
"If it is just a file server then it does not need any special configuration other than setting up a permanently assigned address in the router's DHCP settings. To use the server as a Domain Name Server or router then you have to make other changes to the server, router and computers on the LAN."

How do I assign a permanent address in the router's DHCP settings?

I plan to plug it into the one of the wireless router Ethernet ports.

Thank you again,

Chris
 
Old 05-06-2013, 02:13 PM   #4
Erik_FL
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Quote:
Originally Posted by cromei View Post
How do I assign a permanent address in the router's DHCP settings?

I plan to plug it into the one of the wireless router Ethernet ports.
First, set the server to obtain an IP address automatically. Connect the server to the Ethernet port on the router and test internet access from the server. After it is working, make a note of the IP address and the Ethernet MAC address. You can list those using the "ifconfig" command. The MAC address is to the right of the word "ether" in the information. For example:

Code:
ether 08:00:12:af:01:2e
The router identifies computers based on their Ethernet MAC address.

Use the web browser to access the router's configuration pages. Under "Router Settings" click "Connectivity". Click the "Local Network" tab. Click "DHCP Reservations".

You will see a list of the assigned IP addresses, device names and the last byte of each MAC address. In the above example the last byte is "2e".

Put a check mark next to the address for your server. Then click the "Add DHCP Reservatios" button. You should see that your server has been added to the DHCP Reservations list at the bottom of the page. To change the IP address of the server, click on the information in the DHCP Reservations List and then click "Edit".

As you can see it is easiest to add a device that has already requested an IP address from the router. If you need to add a device that does not show up in the list, there are a few tricks. Add a reservation for a device that does appear in the list, that you don't care about. Then edit it afterward with the correct IP and MAC address. Or, edit an existing entry, changing the IP and MAC address. Then re-add the existing entry from the computers that do appear in the list.

After you have added an IP address to the DHCP reservations list, the router will always automatically assign the same reserved IP address to the computer. You can change the computer to assign the IP address manually if you want. The router will never automatically assign the reserved IP address to any other computer (the MAC address won't match). Note that reserving an IP address in DHCP does not prevent some other computer from being manually set to the same IP address.

There are some other special situations that you might run into and I won't try to explain fully. You can manually assign more than one IP address to an Ethernet port on a computer. That's called multi-homing. The router is probably not going to allow two different IP addresses to be reserved using the same MAC address. You might need to reserve an IP address for a device where you don't know the MAC address. In rare cases the MAC address of a device might be unpredictable. You can cover those situations in two ways. Change the range of addresses assigned by the DHCP server to not assign a particular block of IP addresses. Or, reserve individual IP addresses by entering fake MAC addresses that are not used by any device on your network. With either method you have to assign the IP address on the device manually, since the DHCP server will never assign the reserved IP addresses automatically.

The Linksys User Guide for the router could be better, but it does have a lot of useful information. Here's a link to download the User Guide.

Linksys EA-Series User Guide

Last, I'll mention a few potential problems with satellite broadband. The signal has to travel from the ground, to the satellite and back down to the ground again. That can introduce delays of a half second to over a second. Most of the time that doesn't hurt anything but it can slow down some things. The router may have some features to automatically detect if the Internet is connected. Routers do that by sending commands to the name servers or sites to obtain the time-of-day. If you have problems with your connection dropping unexpectedly, try changing the settings in the router for the Internet connection. There may be settings such as "Always connected", "Reconnect after n seconds" or "automatically check for connection". You may have to change those settings if you have problems. You can usually look at the status log in the router to see if you are getting a lot of messages about the Internet connection dropping.
 
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Old 05-16-2013, 10:07 AM   #5
cromei
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Registered: May 2013
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Thanks again for all your time and effort producing such a clear, concise, and succinct response.
All the best,
Chris
 
  


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