freebsd stable - Aug 2010 - 8.1R: ppp default route uses wrong Netif (with pppoe)

Hi,
I found the following problem with ppp after upgrading to 8.1

I am using ppp -ddial -nat ... over pppoe.  The entry in ppp.conf has
these lines (plus others not relevant here):

    my-provider:
        set line PPPoE:nfe0
        ...
        add default HISADDR

Up to 7.2 this sufficed to establish a route using 'tun0' as the device

    Destination        Gateway            Flags    Refs      Use  Netif Expire
    default            81.174.0.1         UGS         0     1885   tun0

With the upgrade to 8.1R the default route points to 'nfe0', i.e. the
device used to talk pppoe, instead of tun0.
This causes a number of failures which prevent operation.

I am not sure though whether the bug is in PPP or in the kernel,
and why ppp now uses the wrong device to install the route entry.

A functional workaround is the following (note you need all three lines!):

        add default HISADDR
        shell route delete default
        shell route add default -interface INTERFACE

where the first line installs the bogus entry but supplies a default
address for outgoing packets, and the other two entries fix
the interface.

I tried to remove the 'add default HISADDR' but it does not seem
to work -- tcpdump shows outgoing packets carrying 0.0.0.0 as src-ip,
which prevents replies from coming back.

I'll submit a PR later, but would be curious to know if someone
has ideas on what could be a proper fix.

cheers
luigi

Luigi Rizzo <rizzo@iet.unipi.it> wrote:
 > Hi,
 > I found the following problem with ppp after upgrading to 8.1
 > 
 > I am using ppp -ddial -nat ... over pppoe.  The entry in ppp.conf has
 > these lines (plus others not relevant here):
 > 
 >     my-provider:
 >         set line PPPoE:nfe0
 >         ...
 >         add default HISADDR
 > 
 > Up to 7.2 this sufficed to establish a route using 'tun0' as the
device
 > 
 >     Destination        Gateway            Flags    Refs      Use  Netif
Expire
 >     default            81.174.0.1         UGS         0     1885   tun0
 > 
 > With the upgrade to 8.1R the default route points to 'nfe0', i.e.
the
 > device used to talk pppoe, instead of tun0.
 > This causes a number of failures which prevent operation.

That's strange ...  I have a simuilar setup on my router
which was upgraded from FreeBSD 6.x to 8.x recently.
I don't have any routing problems.  So maybe it is a
problem with your configuration, not a FreeBSD bug.

My rc.conf contains:

    ifconfig_fxp0="up"
    ppp_enable="YES"
    ppp_mode="ddial"
    ppp_nat="YES"
    ppp_profile="pppoe_myisp"
    gateway_enable="YES"

And ppp.conf looks like this (few things omitted for brevity):

    default:
      set ifaddr 10.0.0.1/0 10.0.0.2/0
      set server /var/run/ppp.ctl "" 0177
      nat enable yes

    pppoe_myisp:
      set device PPPoE:fxp0
      set authname myauthname
      set authkey myauthkey
      set dial
      set login
      add default HISADDR
      enable dns
      resolv readonly

The default route is set correctly:

    $ route get default
       route to: default
    destination: default
           mask: default
        gateway: gateway.myisp.net
      interface: tun0
          flags: <UP,GATEWAY,DONE,STATIC>
     recvpipe  sendpipe  ssthresh  rtt,msec    mtu        weight    expire
           0         0         0         0      1492         1         0

Best regards
   Oliver

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As I understand this isn't a bug but a mistype or misunderstand of config (
see man ppp.conf )

I'm running myself 8.0, 8.1 and currently 8.STABLE with pppoe in this way
and never have a problem as many peolpe do.
Look in listing
> my-provider:
> set line PPPoE:nfe0
Here's some "set line" and should be "set device" like
this:
> pppoe_myisp:
> set device PPPoE:fxp0
I think that's the clue.