Re: [Discuss] Changing Comcast Modem to Bridged
On 12/30/18 2:29 PM, Gregory Galperin wrote: On Sun, Dec 30, 2018 at 11:39:24AM -0500, jbk wrote: The problem with doing that is there is no way to turn off the Comcast dhcp server w/o putting it into bridged mode, other than limiting the range to a single address and have that lease set to forever. But forever on the modem can't you reserve a static ip in the comcast router outside its dhcp range, and set up your own router to uplink on that static ip? --grg No, only within the range. These modems are really locked down to prevent people like me becoming headaches for their support staff. I'm now bridged and after a few hours have internet connection through the new router. It took a while and I'm not sure why. I need to finish the setup of my virtual access point. -- Jim Kelly-Rand j...@kjkelra.com ___ Discuss mailing list Discuss@blu.org http://lists.blu.org/mailman/listinfo/discuss
Re: [Discuss] Changing Comcast Modem to Bridged
On 12/30/18 11:55 AM, Robert Krawitz wrote: On Sun, 30 Dec 2018 11:39:24 -0500, jbk wrote: On 12/30/18 11:01 AM, Robert Krawitz wrote: On Sun, 30 Dec 2018 10:39:06 -0500, jbk wrote: A couple years ago we changed to comcast as our ISP and incorporated their modem into our network topology providing the dhcp, NAT and wireless functions. Prior to this we had a DSL modem and WRT54G running tomato. The modem provided dhcp so it was the gateway address. I now want to put the Comcast modem in bridge mode and have my wireless router running dd-wrt provide the dhcp and NAT for the wireless and wired LAN. I've done that by the simple expedient of connecting our domestic router to our (RCN -- it doesn't matter) router, and having everything else except for my server system connect to our domestic router. In other words, a DMZ topology. The only thing I had to configure on the RCN router was the port forwarding to any ports I want open on the server. If you don't have a static IP/no open ports, it's even easier; the only two things on the DMZ are the ISP router and the domestic router. The problem with doing that is there is no way to turn off the Comcast dhcp server w/o putting it into bridged mode, other than limiting the range to a single address and have that lease set to forever. But forever on the modem is only as long as that device remains connected without interruption. If there is an interruption, power outage, then the first device detected on resumption will get that address lease. You don't need to turn off the DHCP server on the Comcast router, because you're only going to have one device attached to it, your domestic router. Everything else connects to your domestic router, which you configure as you please; you connect the domestic router's uplink to the Comcast router and let the Comcast router assign the domestic router whatever address it pleases. Thanks Robert, I would have to do a lot more research to see what setting up a DMZ would mean to my topology and the dhcp issue is the biggest headache and bridge mode is the only way to turn it off on the modem. Here's the configuration I'm suggesting. The "=" network is the DMZ, but it's simply an ethernet connection: + Internal device 1 | INTERNET - Comcast = Domestic --+ Internal device 2 | + Internal device ... >From the standpoint of the Comcast router, it sees that it's connected to the Internet and to one device internally (you can even turn off the wireless altogether on it). From the standpoint of the domestic router, it sees the Comcast router as the internet, and all of your other devices connected to it. Mine's a little different because of my server, which is connected to both the DMZ and the internal domestic network but doesn't route: + Internal deviceS | INTERNET -ISP/dhcp1 ==Router+dhcp2/WAP/VAP | +-internal Server Currently all of my devises point to ISP/dhcp1's IP as the gateway. Would I now want to have these devices point to the modem assigned dhcp address of Router/dhcp2 or the LAN address I assign to dhcp2. This is where my confusion is. -- Jim Kelly-Rand j...@kjkelra.com ___ Discuss mailing list Discuss@blu.org http://lists.blu.org/mailman/listinfo/discuss
Re: [Discuss] Changing Comcast Modem to Bridged
On 12/30/18 10:49 AM, Dan Ritter wrote: jbk wrote: A couple years ago we changed to comcast as our ISP and incorporated their modem into our network topology providing the dhcp, NAT and wireless functions. Prior to this we had a DSL modem and WRT54G running tomato. The modem provided dhcp so it was the gateway address. I now want to put the Comcast modem in bridge mode and have my wireless router running dd-wrt provide the dhcp and NAT for the wireless and wired LAN. According to the research I've done there are only two ip address options for setting up the modem in bridge mode. 10.0.0.1 or 192.168.100.1. My current network subnet mask is 255.0.0.0 for the dozen or so devices that have static IP's. I do not provide any services outside the local LAN but within I have a backup server that serves a number of devices. As I understand it the modem IP in bridged mode wants to be on a different subnet that the internal LAN which would lead me to believe that the 192 prefixed IP address would be the choice, this is question #1 Once I've setup the modem with the correct IP then will the router now become the gateway? I have the Cisco DPC3941T modem, has anyone on here set up the bridge themselves, I see the option in the management GUI, or per my web searching this change can only be done correctly by the right Comcast personel remotely? Well that's the gist of it, did I leave out anything? You've got some confusion in there. Yes, I set this network up around 2001 with the help of someone else that new networking better than I. 1. NAT has to be handled by a router which has at least one outside address and at least one inside address. /Which would now be my router in bridge mode./ 2. DHCP can be done by any device on the inside. 3. A bridge operates at the ethernet level, not the IP level. So once it's in operation, you pretend it's a chunk of wire: your router connects to the bridge and uses the Comcast assigned outside address(es), and connects to your internal network with internal address(es). /So the router LAN address will now become the gateway address on my internal network?/ A subnet mask indicates how large a chunk of the IP space should be considered as local. You've got 16.7 million addresses considered local right now... /Yes, I only learned this later after I had made all these other static decisions/ The net says: Cisco DPC3941T modem 1) Press and hold reset button on back of gateway for 30 seconds, this will reset the gateway back to the factory defaults.. 2) Connect a computer to ethernet port #2 on the back of the gateway. 3) After the gateway boots, verify computer has connectivity, connect to gateway @ 10.0.0.1 4) Change the gateway's login password, disable both private wifi networks, set ipv4 and ipv6 firewall to custom mode and select option disable/none. 5) Set Gateway > At a Glance > Bridge Mode to Enable. When you see the timer screen pop up, you can disconnect the computer from the gateway as it is rebooting. the reboot can take 3 - 5 minutes. 6) Connect your router to the gateway ethernet port #1, on the router make sure that the WAN / Internet link is set to disabled or off. 7) Once the gateway completes it's boot cycle, enable the Internet WAN on the router. The router should now have the IP address issued by Comcast. 8) Configure the router as you see fit. Hope that helps. -dsr- Thanks Dan, I did see the instructions on the net of the steps you outline here, but out of context of my network. DD-WRT has a lot of helpful information on their site and forums and I am confident once the modem is in bridge mode I can implement a network more tailored to our needs including a VAP to get our frequent guests off our local LAN. Jim -- Jim Kelly-Rand j...@kjkelra.com ___ Discuss mailing list Discuss@blu.org http://lists.blu.org/mailman/listinfo/discuss
Re: [Discuss] Changing Comcast Modem to Bridged
On 12/30/18 11:01 AM, Robert Krawitz wrote: On Sun, 30 Dec 2018 10:39:06 -0500, jbk wrote: A couple years ago we changed to comcast as our ISP and incorporated their modem into our network topology providing the dhcp, NAT and wireless functions. Prior to this we had a DSL modem and WRT54G running tomato. The modem provided dhcp so it was the gateway address. I now want to put the Comcast modem in bridge mode and have my wireless router running dd-wrt provide the dhcp and NAT for the wireless and wired LAN. I've done that by the simple expedient of connecting our domestic router to our (RCN -- it doesn't matter) router, and having everything else except for my server system connect to our domestic router. In other words, a DMZ topology. The only thing I had to configure on the RCN router was the port forwarding to any ports I want open on the server. If you don't have a static IP/no open ports, it's even easier; the only two things on the DMZ are the ISP router and the domestic router. The problem with doing that is there is no way to turn off the Comcast dhcp server w/o putting it into bridged mode, other than limiting the range to a single address and have that lease set to forever. But forever on the modem is only as long as that device remains connected without interruption. If there is an interruption, power outage, then the first device detected on resumption will get that address lease. Thanks Robert, I would have to do a lot more research to see what setting up a DMZ would mean to my topology and the dhcp issue is the biggest headache and bridge mode is the only way to turn it off on the modem. -- Jim Kelly-Rand j...@kjkelra.com ___ Discuss mailing list Discuss@blu.org http://lists.blu.org/mailman/listinfo/discuss
Re: [Discuss] Changing Comcast Modem to Bridged
jbk wrote: > A couple years ago we changed to comcast as our ISP and incorporated their > modem into our network topology providing the dhcp, NAT and wireless > functions. > > Prior to this we had a DSL modem and WRT54G running tomato. The modem > provided dhcp so it was the gateway address. > > I now want to put the Comcast modem in bridge mode and have my wireless > router running dd-wrt provide the dhcp and NAT for the wireless and wired > LAN. > > According to the research I've done there are only two ip address options > for setting up the modem in bridge mode. 10.0.0.1 or 192.168.100.1. > > My current network subnet mask is 255.0.0.0 for the dozen or so devices that > have static IP's. I do not provide any services outside the local LAN but > within I have a backup server that serves a number of devices. > > As I understand it the modem IP in bridged mode wants to be on a different > subnet that the internal LAN which would lead me to believe that the 192 > prefixed IP address would be the choice, this is question #1 > > Once I've setup the modem with the correct IP then will the router now > become the gateway? > > I have the Cisco DPC3941T modem, has anyone on here set up the bridge > themselves, I see the option in the management GUI, or per my web searching > this change can only be done correctly by the right Comcast personel > remotely? > > Well that's the gist of it, did I leave out anything? You've got some confusion in there. 1. NAT has to be handled by a router which has at least one outside address and at least one inside address. 2. DHCP can be done by any device on the inside. 3. A bridge operates at the ethernet level, not the IP level. So once it's in operation, you pretend it's a chunk of wire: your router connects to the bridge and uses the Comcast assigned outside address(es), and connects to your internal network with internal address(es). A subnet mask indicates how large a chunk of the IP space should be considered as local. You've got 16.7 million addresses considered local right now... The net says: Cisco DPC3941T modem 1) Press and hold reset button on back of gateway for 30 seconds, this will reset the gateway back to the factory defaults.. 2) Connect a computer to ethernet port #2 on the back of the gateway. 3) After the gateway boots, verify computer has connectivity, connect to gateway @ 10.0.0.1 4) Change the gateway's login password, disable both private wifi networks, set ipv4 and ipv6 firewall to custom mode and select option disable/none. 5) Set Gateway > At a Glance > Bridge Mode to Enable. When you see the timer screen pop up, you can disconnect the computer from the gateway as it is rebooting. the reboot can take 3 - 5 minutes. 6) Connect your router to the gateway ethernet port #1, on the router make sure that the WAN / Internet link is set to disabled or off. 7) Once the gateway completes it's boot cycle, enable the Internet WAN on the router. The router should now have the IP address issued by Comcast. 8) Configure the router as you see fit. Hope that helps. -dsr- ___ Discuss mailing list Discuss@blu.org http://lists.blu.org/mailman/listinfo/discuss
