sharing an internet connection

[VJ]

Hello,

I have tried it a couple of times, but was unsuccessful so far... I have a situation where there is a wireless router and a couple of pc's (both wired and wireless). The router gives every pc its IP address (dhcp), but that is about all it does.
For an internet connection, I use a mobile phone connected via either USB or bluetooth. Following advice in a previous thread, I managed to set correct network priorities (so I can have my internet connection and my local network connection).

Now I'd like to share that internet connection...
(I'm waiting for a new computer, making this sharing very important...)

Just right clicking "Allow other network users to connect through this computer’s Internet connection" doesn't seem to do the trick... Seeing the Howto makes me think I might be running into IP address issues...
Should I disable the DHCP server on the router?
Which IP adress should I give it (currently = 192.168.2.1)?
What about wireless clients... do they get their IP from the router or from the gateway-PC?
Thanks!


Jörg

[MultimediaMan]

The default gateway of the clients will need to be set to the gateway-PC's internal IP address.

How you do that is a function of your DHCP Server.

[VJ]

But who is the dhcp server? My router or the gateway pc? And what for the wireless connected computers?

[VJ]

Just a though: what if I'd connect the internet port of the router to the gateway PC?

The router's "external" ip may be assigned by the gateway pc, all other pc's would get an ip from the router's dhcp function and can route through it...

[MultimediaMan]

That may work - you'd be double NAT'ed which could screw up secure communications. There is no rule which says the DHCP server also double as the Gateway device (although a lot of Routers enforce that by virtue of their firmware).

The Gateway PC should be serving DHCP to the 192.168.0.x subnet, IIRC. I don't know if you can change that easily using ICS.

[VJ]

The microsoft howto states that ICS is incompatible with other DHCP servers. This made me assume I'd have to disable dhcp on the router (in the situation where all pc's are connected to the "internal" ports). But I don't know if wireless clients will be properly dealt with (hence the internet port-to-gateway pc idea), nor what IP addresses the microsoft system will assign (the auto-assigned addresses are usually weird, and I'd like to keep track of addresses).

When using the internet port, I feel I might have more control... didn't know that double NAT could be an issue though... Something to try though.

At the moment, I don't have the gear yet (may take a couple of weeks), but I'm trying to learn more about it before dealing with it.

[VJ]

On more thing: when using the internet port, is it possible for the gateway-pc to connect to the pc's on the internal network ports?

[VJ]

This is from the howto

Do not use ICS on a network with domain controllers, DNS servers, gateways, or DHCP servers. And don't use ICS on systems configured for static IP addresses.

[VJ]

Just asked our local sysadmin:

Basically similar comments:
double nat should work, but imposes limitations on network access (from gateway pc to "internal" clients not possible).
Best approach: disable dhcp in the router, ICS should make it possible to select IP address range and should assign IP addresses to all pc's (including wireless connected ones).


Jörg

[VJ]

Hello,

I had some others thing to attend to first, but now I'm ready to pick it up.
The easiest configuration for the time being would be a double nat: it would suffice and require the least modifications of the network (I'd like the local network to still work without the internet connected computer present).

In this situation, I'd connect the laptop's utp connection to the internet port of the router. How should I configure the laptop? Or is it simply a matter of configuring it to share the
ndis connection (=from the phone)?

(I had a utp cable, but it seems to have problems - even in normal situation, so I first need to acquire a new utp cable )


Jörg

[Wulfman]

you could get one of the fancy umts-routers, if money is not an issue. they seem to have flooded the austrian market lately with all those 15€/month-hsdpa-internet-15gb-packages.

mfg
wulfman

[VJ]

Thos packages are not possible here: law forbids coupling services with phones/devices, so we pay full price for hardware. But I have my eye on the Option X1, which takes a USB hsdpa modem and supplies ethernet/wifi and is said to come out soon. The preorder prices seem quite reasonable as well.

In the mean time, I'd thought I'd use my laptop/mobile combination as hsdpa modem.
(I need an internet connection on machines that don't support the USB modem connection... )

I just don't know whether I should simply "share this internet connection" (I thought this only works between windows pc's), or whether I should simply bridge the internet and lan connections on the laptop. The router needs to be assigned an external IP, and I'm not sure how to accomplish this...

Basically, the situation is this:
internet --hsdpa-> phone --usb-> laptop --utp-> router internet port --utp--> other pc's
(the phone presents itself as an rdnis network connection)

[VJ]

Ok, the default internet sharing functionality cannot be used: it wants to assign 192.168.0.1 to the lan connector of my laptop, but it conflicts with the ip-address of the mobile (which I cannot change). I figured I'd try configuring xp as a network bridge... and it almost works:

This is the configuration:

segment 1 (mobile-->laptop):
mobile: IP-address = 192.168.0.1 (fixed)
laptop: IP-address = 192.168.0.102 (obtained from modem)
subnet mask: 255.255.255.0
gateway, dhcp, dns = 192.168.0.1
=> internet connection works from laptop

segment 3 (internal lan behind router):
router ip (lan): 192.168.2.1
pc: 192.168.2.100 (obtained via dhcp)
subnet mask:255.255.255.0 (dhcp)
gateway, dhcp, dns = 192.168.2.1
=>local network works

segment 2 (laptop --> WAN port of router)
laptop ip (lan) : 192.168.3.1 (static), with higher metric value than the modem connection
subnet mask: 255.255.255.0 (static)
gateway, dns: 192.168.3.1 (static)

router ip (wan): 192.168.3.2 (static)
subnet mask: 255.255.255.0 (static)
gateway, dns: 192.168.3.1 (static)
=> assigned dhcp on segment 3 becomes 192.168.3.1

results
from within segment 3, I can ping 192.168.0.102
from segment 1, I have internet access
from within segment 3, I cannot ping 192.168.0.1
the diagnostics section of the routers' webinterface also cannot ping 192.168.0.1
segment 3 has no internet access (a result from the above two things I think)

Any suggestions?
The fact that I can ping 192.168.0.102 from within segment 3 seems to indicate to me that part of the configuration works, as it is able to find a router to another segment...

This is the route information of the laptop:

C:\Documents and Settings\jv>route print
===========================================================================
Interface List
0x1 ........................... MS TCP Loopback interface
0x2 ...xx xx xx xx xx xx ...... Intel(R) PRO/Wireless 2915ABG Network Connection - Packet Scheduler Miniport
0x4 ...xx xx xx xx xx xx ...... Bluetooth LAN Access Server Driver - Packet Scheduler Miniport
0x30006 ...xx xx xx xx xx xx ...... Windows Mobile-based Internet Sharing Device - Packet Scheduler Miniport
0x30007 ...xx xx xx xx xx xx ...... Realtek RTL8139/810x Family Fast Ethernet NIC - Packet Scheduler Miniport
===========================================================================
===========================================================================
Active Routes:
Network Destination        Netmask          Gateway       Interface  Metric
          0.0.0.0          0.0.0.0      192.168.0.1   192.168.0.102       30
          0.0.0.0          0.0.0.0      192.168.3.1     192.168.3.1       40
        127.0.0.0        255.0.0.0        127.0.0.1       127.0.0.1       1
      192.168.0.0    255.255.255.0    192.168.0.102   192.168.0.102       30
    192.168.0.102  255.255.255.255        127.0.0.1       127.0.0.1       30
    192.168.0.255  255.255.255.255    192.168.0.102   192.168.0.102       30
      192.168.3.0    255.255.255.0      192.168.3.1     192.168.3.1       40
      192.168.3.1  255.255.255.255        127.0.0.1       127.0.0.1       40
    192.168.3.255  255.255.255.255      192.168.3.1     192.168.3.1       40
        224.0.0.0        240.0.0.0    192.168.0.102   192.168.0.102       30
        224.0.0.0        240.0.0.0      192.168.3.1     192.168.3.1       40
  255.255.255.255  255.255.255.255    192.168.0.102   192.168.0.102       1
  255.255.255.255  255.255.255.255      192.168.3.1               2       1
  255.255.255.255  255.255.255.255      192.168.3.1     192.168.3.1       1
  255.255.255.255  255.255.255.255      192.168.3.1               4       1
Default Gateway:       192.168.0.1
===========================================================================
Persistent Routes:
  None

Thanks!

[VJ]

If I were to move to static IP addresses, how could I acchieve it then?


Jörg

[Marshmallowman]

I am not sure you want to be showing your mac address on a public forum...