PPPOE and DHCP on some interface, broadcast routing



  • I recently moved into a university-run apartment complex. The rooms have an rj45 jack with which you connect to a large complex-wide network. To connect to the internet you then use a PPPOE connection and log in with you university username/password.

    I don't really like this arrangement as it exposes one to a huge network and one can only have a single computer connected to the internet at the a time. After some investigation I managed to solve those problems by building a pfSense machine (which I've come to love), but there's still a few niggles.

    This is my current network layout, which works pretty fine. Packets go where they should, I can transparently connect multiple computers to both the internet and apartment network:

    However:
    1. Is it possible to consolidate the PPPOE and DHCP links into one interface (like Windows does?) Doing so would greatly simplify my network.
    2. Is there any way to route broadcast packets from my LAN to the 172.x.x.x network? Currently I can only access computers on the apartment complex network by entering their complete name (including domain), I'd greatly prefer it if I'd be able to just find them with Windows Explorer, game server browsers etc.
    3. Also, I currently use manually entered DNS servers. These are on the apartment complex LAN and are (fortunately) able to resolve both local and internet IP addresses. What would happen if I don't use a manually entered server, but set it to use an assigned one? Will the PPPOE's DNS server (only internet) or the DHCP connection's DNS server (both internet and local) be used? Or is this behaviour unpredictable?

    Any help would really be appreciated!



    1. It would be possible but it's not possible by only using the webgui. In case you want to get rid of interfaces and a switch consider using a small vlan capable switch. This way you could use a single switch and have everything else running on and be seperated by vlans.
    2. Broadcasts don't leave the own subnet, therefor you won't be able make that work easily.
    3. If you use autoassigned dns servers you won't be able to manually enter one. You could use the manual assignment and enter the internal dns server as first dns and the pppoe dns as second dns server. However, if the first server answers the request the second one will never be consulted. Another option is to use the pppoe dns as first dns server and use the dns-forwarder to send special domains only to the university internal dns (services>dns-forwarder).


  • Thanks for the reply, that's exactly the information I was after. To clarify my third question, I was only wondering what would happen if you set the DNS forwarder to use an automatically assigned DNS server, while at the same time you have multiple WAN connections that are assigned a DNS. Will it use them in order the interfaces (ie WAN, then OPT1 etc), pick a random one… just curious.



  • The dns forwarder will just work like as dns client running on the pfSense. it will first use the first dns and only if that one fails use the second dns unless you have mappings for dedicated domains to use a special dns server.


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