router doesn't work if rebooted while network is down

Matthew Dillon dillon at
Sat Jun 15 11:55:01 PDT 2013

:Last night the power blinked for a second, which took the cable signal down. I 
:restarted the router. The cable signal is now up, and I have an external 
:address, but I can't ping out from my other boxes. I ran "pfctl -s rules" and 
:saw this wrong line:
:block drop in inet from to any
:where is the address that the cable modem gives when it has no 
:signal. Reloading the rules corrects the address, but I still can't ping out 
:from the router. I can't do "rcrun restart netif" because of bug 2425. I have 
:to reboot it; then everything works. How can I fix it?

    What is happening is that the cable modem is serving a non-routable
    IP address to your computer when the cable modem does not have
    connectivity, instead of the routable address it would normally serve

    The easiest solution is to tell your computer's dhclient to not accept
    that broken address, so dhclient just tries forever until it gets the
    real address.

    You can do this via /etc/dhclient.conf like this:

# specify the correct interface here
interface "em0" {
        supersede routers;
        request subnet-mask;
        require subnet-mask;

    Where you have a reject line for the IP the cable modem would otherwise
    try to assign you.


    The way to manually fix it during testing is to just kill the dhclient
    on the interface and then re-run 'dhclient <interface>'.

					Matthew Dillon 
					<dillon at>

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