bin/44032: pppd: proxyarp is not working

[gergely%egervary.hu@localhost]

>Number:         44032
>Category:       bin
>Synopsis:       pppd: proxyarp is not working
>Confidential:   no
>Severity:       serious
>Priority:       low
>Responsible:    bin-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Wed Nov 03 11:00:00 +0000 2010
>Originator:     Gergely Egervary
>Release:        NetBSD-5
>Organization:
>Environment:
NetBSD galileo.poli.hu 5.1_RC2 NetBSD 5.1_RC2 (GALILEO) #0: Mon Aug 30 12:00:36 
CEST 2010  
root%galileo.poli.hu@localhost:/usr/src/sys/arch/i386/compile/GALILEO i386
>Description:
PPTP server internal network: 10.0.0.0/8 (bge0)
PPTP server internal if: 10.0.0.1
PPTP remote client if: 10.0.0.192

According to syslog, connection is set up properly:

Nov  3 11:46:39 galileo pptpd[17673]: CTRL: Starting call (launching pppd, 
opening GRE)
Nov  3 11:46:39 galileo pppd[16154]: pppd 2.4.4 started by root, uid 0
Nov  3 11:46:39 galileo pppd[16154]: Using interface ppp0
Nov  3 11:46:39 galileo pppd[16154]: Connect: ppp0 <--> /dev/ttyp0
Nov  3 11:46:41 galileo pptpd[17673]: GRE: accepting packet #1
Nov  3 11:46:41 galileo pptpd[17673]: GRE: accepting packet #2
Nov  3 11:46:41 galileo pptpd[17673]: GRE: accepting packet #3
Nov  3 11:46:41 galileo pptpd[17673]: GRE: accepting packet #4
Nov  3 11:46:41 galileo pptpd[17673]: GRE: accepting packet #5
Nov  3 11:46:41 galileo pptpd[17673]: GRE: accepting packet #6
Nov  3 11:46:41 galileo pptpd[17673]: GRE: accepting packet #7
Nov  3 11:46:41 galileo pppd[16154]: MPPE 128-bit stateless compression enabled
Nov  3 11:46:41 galileo pptpd[17673]: GRE: accepting packet #8
Nov  3 11:46:41 galileo pptpd[17673]: GRE: accepting packet #9
Nov  3 11:46:41 galileo pptpd[17673]: GRE: accepting packet #10
Nov  3 11:46:41 galileo pppd[16154]: found interface bge0 for proxy arp
Nov  3 11:46:41 galileo pppd[16154]: local  IP address 10.0.0.1
Nov  3 11:46:41 galileo pppd[16154]: remote IP address 10.0.0.192

Routing on the client is okay. Client can reach 10.0.0.1, but not the full 
remote network. tcpdump on the server network shows there are no response to 
arp who-has requests. On the VPN box, `arp -na` shows no relevant entry.

This setup used to work on good old NetBSD-4 days...

>How-To-Repeat:

>Fix: