IP address increases by one

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Hello

I have 3 laptops, the main is wired to the wireless router and number 2 and 3 have wireless connection. Each accesses the internet with no problem.

The snag is with my no.2 laptop which changes its IP address each time I switch on. At the mo it is 192.168.1.79. This means to have a network up and running I have to input the new address into the firewall so we can all ‘share’

I am running WXP/SP2 and the wireless connection for No.2 is via a Gigabyte WBKG USB wireless Lan card. Firewall is Zonealarm and is set to Internet in the firewall zone. The other 2 are in the trusted zone and remain static(192.168.1.64 and 66). loopback adapter is set at 127.0.0.1 on all 3. Firewall config is identical on all 3 (Apart from ip addresses!!)

Any ideas?

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I assume your router has a DHCP server and is assigning IP addresses to your computers? The easiest thing to do is to enter a subnet in ZoneAlarm and add it to the trusted zone so that your PCs can talk to each other whilst leaving everything else in the internet zone.

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Wide image cropped by HansV

Rory

Thanks for the swift reply. I am unsure on the subnet issue. I have included a jpg of the computer firewall settings on the laptop that increases its IP address by 1 or 2 numbers each time for clarity.

Do you mean add an IP address as a subnet on the main laptop, and then enter the same address on the other 2? Sorry to be a dullard

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Yes, you would enter the same subnet on each machine. In order to know what subnet to enter, you need to know what address ranges the DHCP server on the router is using to assign addresses. Typically, it would be something like 192.168.0.2-192.168.0.254 (with the router itself having address 192.168.0.1), in which case you would enter 192.168.0.0 as the IP address and 255.255.255.0 as the subnet mask. Do you know:
1. Whether your router is in fact acting as a DHCP server?
2. If so, what address range it allocates from? Also, what address it has assigned to it?
Your current addresses are clearly not typical, so did you specifically set them up this way?

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Rory

The router is enabled as a Local DHCP server, with a starting address of 192.168.1.64. The .64 is changeable. There is a box with ‘Maximum number of DHCP users’ filled in with the number ‘191’, which is also changeable. There is an IP of 192.168.1.1 for the router and a subnet mask of 255.255.255.0

The IP addresses of 2 of the laptops, .64 and .66 appeared when I switched them on with the router powered on and have stayed the same since. The laptop with the increasing numbers is obviously going to stop at some stage! Below is a cut and paste of the router status page.

IP Address: 192.168.1.1
Subnet Mask: 255.255.255.0
DHCP Server: Enable
Start IP Address: 192.168.1.64
End IP Address: 192.168.1.254

HTH, thanks.

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Hi,
In that case you should be OK going with the subnet I posted previously. Alternatively you can add an address range to the trusted zone – just use the start and end addresses assigned by the DHCP server – i.e. the 192.168.1.64 – 254 range.
HTH.

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Rory

All laptops now on a subnet. All seeing each other and accessing the internet. The ‘rogue’ laptop with the increasing IP address has been booted twice and the numbers have stayed the same (192.168.1.79). The main laptop still takes several minutes to see the other 2 before showing shared network files and will hang if I access a shared folder and then try to ‘back to’. But as that wasn’t in the opening query, it doesn’t need a reply!!!

I do have other questions regarding IP addressing settings with the laptops, but I think I’ll leave it for now. I have included a firewall pic of what is on laptop 3 FWIW. Despite what you may think, learning has taken place at this end!

Thank you.

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Hi,
I just want to confirm one thing: all your PCs/laptops should have the same subnet, namely:
IP address: 192.168.1.0
Subnet mask: 255.255.255.0

I think we are using different versions of Zone Alarm so I’m not sure if it has converted that subnet to show your current IP address and subnet mask, but I wouldn’t expect it to (and you said your address was 79 not 80) so I suggest you delete the existing subnet on each machine and set them up as above, if that is not what you entered.
I’m also confused as to where that 192.168.1.64 entry came from for the Broadcom adapter – is that one of the other PCs on the network?

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Rory

The .64 entry is the address that appeared when I switched it on (the wireless connection, that is). All 3 laptops have their address at the top of the list in ZA. The .79 laptop has stayed on .79 when I switched on this morning. (How did that happen ?)

I used a subnet of.80 as it was an address that hadn’t been used previously (sorry, Rory, just my twisted thinking!)

When I was setting up everything initially, I couldn’t see the 2 other laptops from my main laptop, so I used the IP addresses that were displayed in ZA and set up each laptop with the addresses of the other 2 and it all worked. (apart from the snag of the increasing IP address). ZA version is 6.1.737.000.

I’ll set 192.168.1.0 etc and get back to you shortly.

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One additional point:
with all your machines on a subnet of 192.168.1.0/255.255.255.0 there should be no need for a separate entry for the 192.168.1.64 address (unless you particularly wanted to put that in the Internet rather than Trusted zone?)

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Rory

The deed is done. Everything still works.

The top line of the ZA entries, specifically, 192.168.1.64, I cannot change, as it is always in use. I cannot delete it as it says ” You cannot delete an active subnet”.

I assume that the entries for the Internet zone, which is the name of each wireless adaptor, was required to access the internet.

Rather than divert your talents this way for any longer, shall we call it a day? I have included a screen grab of laptop 3’s ZA settings that detail your suggested subnet settings.

Now I’m confused… I have set the adaptor (.64) to the trusted zone, and I still have Internet access. I swear it didn’t do that before.

Rory, knock it on the head, mate, I’ll get back to you. Thank you for your thoughts and advice.

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Hi! I’ve been following along learning quite a bit through your questions! Thanks for asking them! I find the settings on the firewall rather confusing too. I am not sure how all of this works but I believe that you can access the internet just fine and have your Broadcom IP address/site in the Trusted zone rather than in the Internet zone. I have mine set up as shown below and I can get both my MAC and PC on the internet through my router which is connected to my cable modem. The MAC and the PC can also “communicate” with each other just fine with my settings as I have them.

Added: Mine is all DHCP enabled – I forgot to add that piece of info.

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Hi Skitterbug,
You don’t actually need the three entries below the subnet entry as the subnet covers all addresses between 192.168.1.1 and 192.168.1.224. Also, if your computers are assigned addresses by DHCP, it doesn’t make sense to assign fixed addresses (though I realise that in a typical home network your PCs probably won’t actually change address and DHCP is actually a little bit of overkill).
FWIW.

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Hi Rory,

No,my IPs are not fixed addresses. Those are the DHCP assigned ones by whatever assigns them! But each computer seems to keep its same DHCP assigned number each time I boot up (which I don’t do often). I’ve wondered whether having the individual IPs in the firewall made any difference in the ability to connect to each other so apparently I don’t need them there. Thank you for making this part of the firewall more understandable!

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The zones exist simply to assign different levels of trust. Typically you assign anything on your internal network to the Trusted zone and everything else is, by default, in the Internet zone. You do not, as you have discovered, need to assign anything to the internet zone in order to access the internet – your router takes care of all that.
Anyway, glad it’s all working!

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