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Static IP Clarity

Static IP Clarity

I have been attempting to do a configuration, but have been unable to find the solutions I need. 


I have a watchguard XTM 330 firewall that I would like to use as the point of entry into my network. I have the comcast business gateway (cisco model), with 5 static IP addresses. 


In order to configure the firewall the way I want it to and need it to, I need to put the business modem into bridge mode (and hand DHCP as well as the static IP routing through the firewall). 


I've read information that says this is not possible to do, and that the comcast modem itself has to handle the static IP address assignment. 


Can a comcast agent confirm or deny if this is actually true or not? I would like to handle all traffic via my own firewall and not use comcasts modem if possible, but want to get information on how to go forward.


Thank you,

Official Employee

Re: Static IP Clarity


Hello workaholicstudios.


I can certainly answer your question in regards to bridge mode and statics. 


You are correct. Bridge mode and static assignment would not be possible. In bridge mode, only internet data would be passing through. All functions such as routing, firewall and static IP assignment are disabled. Static IP addresses will not work and all ethernet ports except for one, will be disabled as well. 


I hope this helps. Please do let me know if you need anything.

Re: Static IP Clarity

So then if I am understanding right, there is no possible way to use my own firewall and am forced to use Comcasts firewall on their hardware?

In order to be able to use my firewall the way it needs to, the firewall has to handle IP assignment, and if the modem/router is doing that that means the firewall can't.
Official Employee

Re: Static IP Clarity

You're not able to use bridge mode with your configuration but you may want to look into using passthrough mode instead. LAN DHCP, the firewall and other functions would be disabled but statics would still route. 

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