Renumbering my network. Any pitfalls?



  • I frequently connect my network to friends and family over VPN to share and communicate.
    But I often run into IP address conflicts because many use the same Private IP Address block.
    So I'm wanting to renumber my network to something very uncommon. There is the 172.16-31.x.x address block that I've never encountered before.
    With things like Camera's, Raspberry Pi's, WiFi Routers, PCs, Smart TVs, etc. does anyone have any experience with renumbering to something other than the standard 192.168.x.x block and any pitfalls when doing so?
    Thanks!!!



  • I should also mention I have a 4 port Router currently set up as:

    Port 1: 192.168.1.x
    Port 2: 192.168.2.x
    Port 3: 192.168.3.x
    Port 3: Wan to Modem
    

    So I want to keep these subnet separate, so maybe moving to a Class B Address is not a good idea?

    Or for a Class B, like 172.16-31.x.x, perhaps set it like this?

    Port 1: 172.16.x.x
    Port 2: 172.17.x.x
    Port 3: 172.18.x.x
    Port 4: Wan to Modem
    

    I guess I could stick with 192.168 and just reassign like this, maybe it would be uncommon enough:

    Port 1: 192.168.201.x
    Port 2: 192.168.202.x
    Port 3: 192.168.203.x
    Port 4: Wan to Modem
    

    Thoughts, opinions, pitfalls?

    Thanks!!



  • There is nothing magical about IP addresses. Just pick a subnet and renumber. Use anything in the rfc1918 space you want:

    10.0.0.0/8
    172.16.0.0/12
    192.168.0.0/16

    They are completely interchangeable. There is nothing spooky about 172.16.0.0/12, just people aren't as used to seeing it as they are with 192.168.0.0/16.



  • So I could something like:

    Port 1: 172.17.1.x
    Port 2: 172.17.2.x
    Port 3: 172.17.3.x
    Port 4: Wan to Modem
    

    With a netmask of 255.255.255.0 and that wouldn't break anything?

    Thanks!


  • Galactic Empire

    This post is deleted!


  • I have no knowledge of your network configuration so I can't say it wouldn't break anything, but there is always going to be disruption if you renumber a network.



  • The opportunities for things to "break" should really only arise in places where you're counting on certain devices being assigned specific IPs. For example, if you have any DHCP static mappings configured, aliases, port forwarding rules, etc. you'll need to review and update them as necessary. But the devices on your network themselves don't care what IPs they get.


  • Netgate

    $ randomlan
    10.138.112.0
    172.18.173.0
    192.168.111.0
    fdb4:b660:d594::/48
    


  • Well, that was a little painful. But its done!
    Used the 172.17.x.x private block.

    LAN1: 172.17.1.x
    LAN2: 172.17.2.x
    LAN3: 172.17.3.x
    

    With net masks of 255.255.255.0

    I also configued DHCP Server and DNS Resolver for as many of the 'static' devices as I could on the network so I won't have to poke at each one if I every do this again. Also set up DNS Resolver for those DHCP devices so I can find them all by name now - I know, its pretty basic, but 'new to me'!
    The only real gotcha was the Wifi Routers: Gotta log into a different interface than the one your working on, otherwise poof you're no longer connected! :)
    Plus they are all in Bridge mode, and with LinkSys routers, if you put them in DHCP mode and Bridge Mode, they disappear from the network and you can no longer access their Admin pages: caveat emptor!
    So they had to be kept Static IPs.
    Thanks for everyones' help and reassurance! No more cross-network conflicts!!
    Yay!!!


  • Netgate

    @leishen said in Renumbering my network. Any pitfalls?:

    No more cross-network conflicts!!

    Until there are. IPv6 will make this a virtual impossibility.

    But 172.17 should pretty much eliminate them for you for now. Good move.


  • Netgate

    Let this thread serve as an example of seeing the problem, setting a maintenance window, and renumbering. It can be a MUCH better path than trying to NAT all the things because you decided to deploy 192.168.1.0/24 or, much worse, 10.0.0.0/8.


  • Banned

    This post is deleted!