Routing problems on VPN servers running FreeBSD 8.0-RELEASE

[Li, Qing]

> 
> It'd be good to resolve this as soon as possible, because I have
> two clients who need servers installed this weekend. (They wanted
> them last week, but I was trapped away from the office by a
snowstorm.)
> 

Luiz Otavio and I have been discussing offline about an issue with
the file /usr.sbin/ppp/arp.c in the past week or so. The ARP related 
code in arp.c was missing a flag bit called "RTF_LLDATA". 

Luiz Otavio and I just had a debug session on your issue. He was
able to reproduce it, and due to the missing RTF_LLDATA bit, the
proxy-arp entry made it into the routing table, which was not
suppose to happen. Since there is already a PPP host entry
for the remote end, you get the FILE EXIST error.
I believe the reason was due to its confusing the kernel code as 
if mpd is installing a routing entry as in 
"route add x.x.x.x/y -iface em0".

So you can wait for Luiz's patch, or you could do it yourself
and try the following 1 line fix:

========================================================================
========
-- usr.sbin/ppp/arp.c	(revision 203430)
+++ usr.sbin/ppp/arp.c	(working copy)
@@ -119,7 +119,7 @@
     return 0;
   }
   arpmsg.hdr.rtm_type = add ? RTM_ADD : RTM_DELETE;
-  arpmsg.hdr.rtm_flags = RTF_ANNOUNCE | RTF_HOST | RTF_STATIC;
+  arpmsg.hdr.rtm_flags = RTF_ANNOUNCE | RTF_HOST | RTF_STATIC |
RTF_LLDATA;
   arpmsg.hdr.rtm_version = RTM_VERSION;
   arpmsg.hdr.rtm_seq = ++bundle->routing_seq;
   arpmsg.hdr.rtm_addrs = RTA_DST | RTA_GATEWAY;
========================================================================
========

I had to reintroduce the RTF_LLDATA flag for compatibility in r187094
back
in Jan. 2009. This change appears to be missing from the ppp port.

Please give the above fix a try and see if it resolves your issue.

-- Qing