Private Modem IP becomes useless DNS server on PPPoE interface?



  • Hey pfDudes,

    This has been bugging me for a while - not new to pfSense but been away a while and this issue still exists. FYI - just got a PC ENGINES apu1c4 and full installed (successfully) on a mSATA SSD.

    So, the issue is, modem IP creeping in as (useless) DNS server in to the pfSense DNS server list… My hardware setup:

    1. Phone line -> ADSL modem
    2. ADSL modem -> pfSense configured as BOTH a) hardware interface and b) PPPoE --- i.e. WAN = PPPoe (on hardware i/f re0) ::: WANprivate = DHCP (on same hardware i/f)
    3. I get an IP from the modem (who knows what IP/subnet it is, DHCP is great!) - cool, at least I know what subnet/IP the modem is on...
    4. The modem (via DHCP) also provides a DNS IP of itself (10.0.0.138) - great, if the modem actually had a connection to the internet this might be useful.
    5. End result: I end up with a 'DNS server(s)' list of:
    a) 127.0.0.1 (great - pfSense caches lookups)
    b) 125.213.163.248 (cool, my ISP's resolver's in there too)
    c) 125.213.172.129 (another ISP resolver)
    d) 10.0.0.138 (oops! this IP has no connection to the internet!)

    The only way around this is to set this (hardware) as static, which implies knowing what it's default IP/subnet is...

    Would be good if pfSense could accept DHCP config for a (non-routing) WAN interface and either exclude it's DNS servers OR (probably easier from a programming point of view) test DHCP DNS servers for resolution and not include them if unsuccessful...

    Hope this makes sense to someone...

    n.