IP Address Problem 1

[tonym29]

I am running a windows XP Pro network with TCP/IP Protocol.
The network is connected to a switch which is then connected to a firewall, the firewall is connected to a adsl router.
Problem: when I take the firewall out of the system everything works ok with the IP addresses being assigned automatically. When I install the firewall the network can not connect ot the internet. With or without the firewall the IP addresses are assigned by the router. I have DHCP active both on win xp and the routed. I cannot see the firewall on the network to configure.

Any help please

 

[manarth]

what make/model of firewall?

Is it possible the firewall is also trying to act as a DHCP server (and so conflicting with your existing IP profile)?

Is the setup like this:
ISP---modem---router---firewall---switch---PCs ?

Is it a proxy or a NAT firewall?

Post back, we'll try and work it out!

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[bcastner]

You want to go modem --> firewall -->router -->switch.

You need to connect a pc directly to the firewall as the only connection. Telnet or however to access the firewall configuration. If it has DHCP services turn them off.

Connect from the firewall to the WAN port of the router. Enable DHCP services, set the router to obtain an IP address automatically or set it to a fixed ip in the range of addresses of the firewall. Set the DHCP range to the default, with the LAN IP of the router at 192.168.1.1, and a suitable number of DHCP addresses beginning say at 192.168.1.100.

Use a regular port on the router to the uplink port of the switch. All clients should be set to get their addresses automatically, although you should specify 192.168.1.1 under advanced settings for the default Gateway.

 

[tonym29]

Marc

The firewall is a 3com office connect secure gateway, and
I believe it is NAT.

It is set up ISP--modem/router---firewall---switch--pc's.

 

[guestgulkan]

If the 3com firewall device is the model: 3Com® OfficeConnect® Internet Firewall 25 then it seems to me
that the router is redundant.
This 3com device has a WAN port, DHCP server capabilities, NAT, etc. Seems no point to having this and the router!

Just inform your adsl ISP provider of the MAC address ( at this point I'm assuming ADSL modems works in the same general way as cable modems) of the firewall device (which is usually written on a label somewhere on the device) and you should be home and dry.

 

[tonym29]

The 3com Gateway is not a modem/router, it has an adsl rj45 connector for connection to a router.

 

[manarth]

Guestgulkan: looking at Tony's description, I guess he has an INTEGRATED modem/router - so he cannot take the router out of the loop..

Tony: your setup ISP--modem/router---firewall---switch--pc's is fine - it just needs appropriate configuration.

BTW, I take it the firewall you refer to is 3com Product # 3CR856-95 (&quot;3Com® OfficeConnect® Cable/DSL Secure Gateway&quot.


The easiest solution will probably be to turn off NAT & DHCP on your router
(btw what model modem/router is it?).

It's an issue of IP allocations - my guess is NAT & DHCP is active on both the firewall AND the modem/router.

Your modem/router has 2 sides - the WAN side gets it's IP from the ISP, and the LAN side is allocated by it's DHCP function (probably using IP 192.168.x.x).

Your firewall's WAN side is given an IP by the router's DHCP, and then uses it's own DHCP server to choose it's own LAN IP (default is 192.168.1.1) and serves IPs to the connected PCs (which receive 192.169.1.x).


As the firewall provides the most versatile NAT functions, the router's NAT & DHCP are redundant - switching them off should probably help resolve the problem. The Public IP (given by your ISP) will then pass through your modem/router and be allocated directly to the firewall's WAN instead.

You configure the firewall by plugging a PC into one of the firewall's ports, open up your browser on the PC, and enter the web address &quot;

http://192.168.1.1&quot;

- i.e. the firewall's LAN IP address.

The firewall's web interface will be fairly intuitive - you can also find your user manual online at:

http://support.3com.com/infodeli/tools/hubs/off-con/pdf/dua08569-5aaa01.pdf

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