Cant access cable modem config - Virgin Media



  • I am on Virgin Media in the UK

    My setup as follows

    SH3 Cable modem is in modem only mode –> WAN interface  Pfsense

    The LAN subnet is 192.168.1.0/24 (pfsense is set to 192.168.1.254)

    Everything is working as designed, however I need to login into the cable modem page to check my power levels, and when I enter 192.168.100.1 I get the pfsense login page.

    I have gone into the WAN Interface config page and ensured this option isnt checked

    Block private networks and loopback addresses

    Any help me



  • In my experience, the modem config is not available when the modem is in bridge mode.  However, your ISP should be able to access the modem through the management software.



  • Add a 2nd IP to you WAN port on the 192.168.100.0/24 subnet (dont add a 2nd gateway).  Then pfsense should route from your LAN to the modem admin page.

    Internet access should till use the regular WAN & Def GW.



  • @pwood999:

    Add a 2nd IP to you WAN port on the 192.168.100.0/24 subnet (dont add a 2nd gateway).  Then pfsense should route from your LAN to the modem admin page.

    Internet access should till use the regular WAN & Def GW.

    Again, I have never seen a config screen be available in bridge mode.  Bridge mode means the config screen, router, etc. are not reachable.  Just to verify, I tried connecting my notebook computer directly to my Hitron cable modem, with an IP address of 192.168.0.66.  Hitron modems have a default address of 192.168.0.1.  I am unable to connect to the modem config.  Also, this is not the first time I have tried to do this.  I had the same results with another modem I had here and others.


  • Rebel Alliance Global Moderator

    @JKnott:

    In my experience, the modem config is not available when the modem is in bridge mode.  However, your ISP should be able to access the modem through the management software.

    If its a modem, then there is no "bridge" mode - if it was a gateway then it could be put into bridge mode - ie just modem mode.

    The standard IP address for many brands of cable modems is 192.168.100.1 - I have never had to do anything special on pfsense to be able to access this.. But yes you can create a vip on your wan connected to the modem and then nat to this vip when wanting to talk to 192.168.100.1

    For example here is my current modem page interface at 192.168.100.1




  • @JKnott:

    In my experience, the modem config is not available when the modem is in bridge mode.  However, your ISP should be able to access the modem through the management software.

    It certainly is but not directly. The bridge interface will have the managment IP address but it will an RFC1918 address which won't be reachable without an IP alias on your WAN interface. This all assuming that we are talking about a straight ethernet bridge on the modem and not some weird PPPoE thingy.


  • Rebel Alliance Global Moderator

    "RFC1918 address which won't be reachable without an IP alias on your WAN interface"

    No not really… Since as long as the IP was not local pfsense would send it out the wan, the modem would see that IP and answer back.. So as long as your not blocking rfc1918 on your wan you should not have an issue talking without having to create the vip.. This has been my experience with the arris/motorola line of cable modems.



  • If its a modem, then there is no "bridge" mode - if it was a gateway then it could be put into bridge mode - ie just modem mode.

    Well, perhaps a bit loose use of terms.  What I have is a box made by Hitron, provided by my cable company.  It is normally configured to be a router/firewall, but can be put into bridge mode, as you'd do when you use a separate router/firewall, as I do.

    It certainly is but not directly. The bridge interface will have the managment IP address but it will an RFC1918 address which won't be reachable without an IP alias on your WAN interface.

    I connected my notebook computer, with a static address of 192.168.0.66 /24.  The default for the Hitron box is 192.168.0.1, so it should appear on the same network as my computer.

    To my knowledge, the only way to restore router mode is to call the support tech, who can then use the management interface, to reconfigure it.  On the user side, when placed in bridge mode, the config interface is no longer reachable.

    As I mentioned, this is not the only device I've tried this with and they all show the same behavior.


  • Rebel Alliance Global Moderator

    "they all show the same behavior."

    And those are not cable modems then… When a cable modem boots it will even hand out IP address in the 192.168.100 space...

    As you stated those are firewall/routers that you put in bridge mode.. So they are gateways that you have disabled the gateway feature and want to use as just a modem..  Or bridge mode - that is completely different than your typical cable modem.. That has no firewall or routing features - its just a Modem!!  Almost all of these answer on 192.168.100.1 as the default.. Atleast the tplink, arris and motorolas etc..



  • I can certainly access my modem that is in proper ethernet bridge mode from my LAN computers, no problem there at all. However, I have to use the IP alias on my pfSense WAN because my WAN has a public IP address and any connection from my pfSense going to the management IP address (192.168.1.1) will just hit the ISP gateway on the upper side of the bridge and be just dropped. Remember, any connection to a foreign address that is not in the routing table of your systems gets passed to the upstream default gateway.

    Edit: Forgot that I also have to use an outbound NAT rule on the WAN that maps the requests going to 192.168.1.1 to the IP alias set on the WAN interface, the modem can't do two-way communication between it and the LAN because it doesn't know the route back to the LAN network.

    Maybe the modem provided by Virgin Media is just configured that way, off the shelf consumer modems usually offer the management interface even in bridge mode.



  • As I mentioned earlier, it's perhaps a loose use of terms.  I have it in bridge mode, which means it functions as a modem.  The address is 192.168.0.1, as listed on a sticker attached to it and here:
    http://setuprouter.com/router/hitron-technologies/ip-address.htm

    In bridge mode, it does not hand out an RFC 1918 address.  I get a (actually 2 available) public IPv4 address and a /56 IPv6 prefix.

    When set up as a router/firewall, it will hand out addresses in the 192.168.0.0 /24 range and provide only a single /64 on IPv6.


  • Rebel Alliance Global Moderator

    And that is not a "cable" modem - that is a gateway… Ie modem/router combo device..

    Which device do you have here? 
    http://www.hitrontech.com/product-category/cable/

    Example here hitron cable modem quick start guide
    https://www.cox.com/content/dam/cox/residential/support/internet/print_media/Hitron_CDA30360_Quick_Reference_Guide.pdf

    And that states 192.168.100.1, etc..

    And I do agree there for sure is misuse of terms.. A modem is just that a modem.. You can't put it i bridge mode because there is no other mode ;)  Its a "modem"  Now if its a gateway then then it can provide multiple functions - it is the modem and router in 1 box.  Which those yes you can put in "bridge mode" which turns off its router functions.. And or they can also have some ports that give you your public while others give you a routed/nated rfc1918 address, etc.

    And then there is just routers - that need a modem in front of them to connect to the internet, etc.

    Even makers use the wrong terms I have seen where they call their gateway device a modem or router, etc.  When its actually a gateway device that has modem and router functions in 1 box..



  • @johnpoz:

    And that is not a "cable" modem - that is a gateway… Ie modem/router combo device..

    Which device do you have here? 
    http://www.hitrontech.com/product-category/cable/

    CGN3ACSMR and it looks like the CGNV4.

    Example here hitron cable modem quick start guide
    https://www.cox.com/content/dam/cox/residential/support/internet/print_media/Hitron_CDA30360_Quick_Reference_Guide.pdf

    And that states 192.168.100.1, etc..

    The sticker on the unit says 192.168.0.1 and that's the address I used to configure it, before I put it in bridge mode.

    And I do agree there for sure is misuse of terms.. A modem is just that a modem.. You can't put it i bridge mode because there is no other mode ;)  Its a "modem"  Now if its a gateway then then it can provide multiple functions - it is the modem and router in 1 box.  Which those yes you can put in "bridge mode" which turns off its router functions.. And or they can also have some ports that give you your public while others give you a routed/nated rfc1918 address, etc.

    I have it in bridge mode, so it functions strictly as a modem.  I haven't seen the router functions in it in about 1.5 years, since I put it in bridge mode.  On this device, there are only 4 connectors on the LAN side.  In gateway mode, they're just 4 switch ports connected to the gateway.  In bridge mode, you can connect 2 devices and get IPv4 & IPv6 addresses for them.  In gateway mode, it's the usual NAT on IPv4 and a single /64 on IPv6.

    And then there is just routers - that need a modem in front of them to connect to the internet, etc.

    Even makers use the wrong terms I have seen where they call their gateway device a modem or router, etc.  When its actually a gateway device that has modem and router functions in 1 box..

    Well, officially, it's a gateway.  But I use it as a modem, with the gateway functions disabled.