Trying to access my Comcast modem via the LAN

bazzacad

It's a public static IP. We have a block of 5 from them. I figured they just assigned the IP to our modem. No it's not pppoe. We don't use IPv6.

Could the "Block private networks..." be the issue?

akuma1x

@bazzacad said in Trying to access my Comcast modem via the LAN:

I'll try the vip option. I looked at the link from kom, but it doesn't seem to make since. I don't have an assign or new OPT interface option under interfaces....

If this is truly the way you need to go, a VIP isn't found under the Interfaces tab. It's located under the Firewall tab in the Virtual IPs item.

Jeff

JKnott

@bazzacad said in Trying to access my Comcast modem via the LAN:

It's a public static IP. We have a block of 5 from them. I figured they just assigned the IP to our modem.

I see you have a static configuration on the WAN side. However, what is the modem doing? If in gateway mode, they will generally use NAT on IPv4 and give you an RFC 1918 address. What happens if you connect a computer directly to the modem, using DHCP? What address does it get?

chpalmer

It's a public static IP. We have a block of 5 from them.

which means you are on commercial service.. which means you are on one of their "Gateway router" modems..

If you plug a laptop directly into the modem can you reach the GUI? They may have changed the TTL on the GUI..

I do know that Comcast in the past has told us that they have to be the ones to configure settings in the modem.. But since the user/password was the default and all over the internet we were able to log in from behind a pfsense hardware box. So I know this has worked for us in the past.

What is the model of the modem?

chpalmer

@JKnott said in Trying to access my Comcast modem via the LAN:

I see you have a static configuration on the WAN side. However, what is the modem doing? If in gateway mode, they will generally use NAT on IPv4 and give you an RFC 1918 address. What happens if you connect a computer directly to the modem, using DHCP? What address does it get?

This is how Comcast does their static IP's. The modem should give out addresses via DHCP in the 10.x.x.x range if they are still doing things the same as 10 years ago. If you want to use your statics you set them manually.

chpalmer

What happens if you set your "gateway" as 10.1.10.1?

bazzacad

Hi everyone, thanks for all the help. Yes, we are a Comcast commercial/business costumer & yes it's a gateway modem. If I plug a laptop directly into the modem, I can access it's UI & I receive a 10.1.10.x address. Screen shot below. I'm hesitant to put it into bridge mode, because we have our UniFi access points connected to it for our guest WiFi. The WiFi clients & AP's also receive 10.1.10.x addresses & since they're on the DMZ side, they can't access our LAN. Maybe "Pseudo" mode would work, anyone know what the difference is? @chpalmer I'm not sure what you mean by "They may have changed the TTL on the GUI", where would I find that?

Here's the model info:

LAN info:

WAN info:

JKnott

@bazzacad said in Trying to access my Comcast modem via the LAN:

If I plug a laptop directly into the modem, I can access it's UI & I receive a 10.1.10.x address.

This proves you're behind NAT. Since you're behind it, you can't configure pfSense with the public address. By doing so, you're creating a situation where pfSense and everything behind it is unable to reach the rest of the world.

chpalmer

@JKnott said in Trying to access my Comcast modem via the LAN:

This proves you're behind NAT. Since you're behind it, you can't configure pfSense with the public address. By doing so, you're creating a situation where pfSense and everything behind it is unable to reach the rest of the world.

Yes he can. That's the way Comcast does their static IP's.

bazzacad

Yes, my pfSense & my workstation on the LAN behind pfSense can reach the world.

JKnott

@chpalmer said in Trying to access my Comcast modem via the LAN:

Yes he can. That's the way Comcast does their static IP's.

Given that NAT is apparently used, how do public addresses reach the LAN? The pictures above show 50.247.X.y on the WAN side and 10.0.0.0 /24 on the LAN. All they can do in that setup is NAT the addresses individually to corresponding LAN addresses.

chpalmer

@bazzacad said in Trying to access my Comcast modem via the LAN:

I'm not sure what you mean by "They may have changed the TTL on the GUI", where would I find that?

If that truly is the case it is a hard coded number in the code. Not something that you would change. My guess is that it would have changed during a firmware update of the modem. TTL or Time to Live. The TTL number gets reduced by 1 each time you transverse a router. If you start with a TTL of 1 then you cannot go past any other router. Since ping works for you I have to guess that this is the case. You could ask Comcast Customer Support to set the TTL to a higher number and see if you can stump them?

How bad do you actually need those static IP's?
How important is it that you access the modem GUI constantly?

chpalmer

@JKnott

The gateway modem that Comcast uses is a router. I do not know all the black magic they are using but I know it works this way. They will not set the modem as bridge mode if you have static addresses you need to use.

chpalmer

https://business.comcast.com/help-and-support/internet/using-a-static-ip/#use-your-static-i-ps-to-run-a-server-i-pv-4

https://www.handymanhowto.com/how-to-configure-a-comcast-business-class-static-ip-address/

JKnott

@chpalmer said in Trying to access my Comcast modem via the LAN:

@JKnott

The gateway modem that Comcast uses is a router. I do not know all the black magic they are using but I know it works this way. They will not set the modem as bridge mode if you have static addresses you need to use.

As I mentioned, the pictures show a 10.0.0.0 /24 address on the LAN side, which means they're using NAT. It may be they're mapping individual public addresses to the LAN addresses. Regardless, it's still NAT, which means using pfSense in the usual router mode won't work. In this case, it has to be configured to filter, without routing.

chpalmer

@JKnott said in Trying to access my Comcast modem via the LAN:

As I mentioned,

Yep.. I get it.. But read the article from handymanhowto I linked above.

bazzacad

Thanks for all the help. The the public IP address are important to use for things like our FreePBX server, VPN access from the outside, and a hosted web site. I guess accessing the modem GUI from the LAN isn't that important. I just have to walk to the server room & connect a laptop to it. It's just frustrating, because it was working before and it stopped working with we upgraded to the pfSense appliance, so that makes me think it wasn't a firmware update on the modem.

chpalmer

@bazzacad said in Trying to access my Comcast modem via the LAN:

so that makes me think it wasn't a firmware update on the modem.

I don't have any static Comcast sites left to test..

You are plugged into the first port on the modem?

JKnott

@bazzacad said in Trying to access my Comcast modem via the LAN:

We don't use IPv6.

Check again. According to the pictures you provided, you have a prefix assigned to you. It's 2603:3024:1003:4500:: /56. That means if you were using pfSense as intended, you'd have 256 /64 IPv6 networks, each of which could have up to 2^64 addresses. However, it also appears they're putting the /56 directly on the LAN, which won't work. The LAN should have only a /64 and nothing else. Is there anywhere in that modem to select a single /64? With the Hitron modem I have, in router mode, it provides only a single /64, but in bridge mode I get the full /56.

JKnott

@chpalmer said in Trying to access my Comcast modem via the LAN:

Yep.. I get it.. But read the article from handymanhowto I linked above.

NAT has gone from being a hack to get around the IPv4 address shortage to a curse on networking. If you have a block of public addresses, why the @$^$^#%$&$ should you be forced to use NAT? NAT breaks things and with that setup, they're forcing you to use it.