[pptp-server] repost: PPTPD under NetBSD: Proxy Arp not working?

[Simson L. Garfinkel]

[I just joind the mailing list and posted this, but it doesn't look like it
went through. Perhaps the mailing list program wouldn't allow me to post until
I had my subscription authenticated? I'm not sure, so I'm reposting this here.]

Hi there. I'm trying to get PPTPD to run under NetBSD 1.4. The server compiled
just fine, it receives incoming connections just fine, it starts up pppd just
fine, and then I have problems.  Specifically, the pppd on the NetBSD box seems
unable to exchange packets with the ppp client on the Win95 box.

It seems that the problem is that the IP addresses being assigned to the PPTPD
process are not accessible from the NetBSD box. I've tried assigning IP
addresses both on the local subnet and off, and neither seems to work.

Here is typical trace:

Oct  9 19:35:12 walden pptpd[994]: MGR: Reaped child 995
Oct  9 19:35:23 walden pptpd[999]: MGR: Launching /usr/local/sbin/pptpctrl to
handle client
Oct  9 19:35:23 walden pptpd[999]: CTRL: local address = 192.168.0.235
Oct  9 19:35:23 walden pptpd[999]: CTRL: remote address = 192.168.1.235
Oct  9 19:35:23 walden pptpd[999]: CTRL: pppd speed = 115200
Oct  9 19:35:23 walden pptpd[999]: CTRL: Client 195.36.211.41 control
connection started
Oct  9 19:35:23 walden pptpd[999]: CTRL: Received PPTP Control Message (type:
1)
Oct  9 19:35:23 walden pptpd[999]: CTRL: Made a START CTRL CONN RPLY packet
Oct  9 19:35:23 walden pptpd[999]: CTRL: I wrote 156 bytes to the client.
Oct  9 19:35:23 walden pptpd[999]: CTRL: Sent packet to client
Oct  9 19:35:23 walden pptpd[999]: CTRL: Received PPTP Control Message (type:
7)
Oct  9 19:35:23 walden pptpd[999]: CTRL: Set parameters to 0 maxbps, 16 window
size
Oct  9 19:35:23 walden pptpd[999]: CTRL: Made a OUT CALL RPLY packet
Oct  9 19:35:23 walden pptpd[999]: CTRL: Starting call (launching pppd, opening
GRE)
Oct  9 19:35:23 walden pptpd[999]: CTRL: pty_fd = 4
Oct  9 19:35:23 walden pptpd[999]: CTRL: tty_fd = 5
Oct  9 19:35:23 walden pptpd[999]: CTRL: I wrote 32 bytes to the client.
Oct  9 19:35:23 walden pptpd[1000]: CTRL (PPPD Launcher): Connection speed =
115200
Oct  9 19:35:23 walden pptpd[999]: CTRL: Sent packet to client
Oct  9 19:35:23 walden pptpd[1000]: CTRL (PPPD Launcher): local address =
192.168.0.235
Oct  9 19:35:23 walden pptpd[1000]: CTRL (PPPD Launcher): remote address =
192.168.1.235
Oct  9 19:35:23 walden pppd[1000]: pppd 2.3.5 started by simsong, uid 0
Oct  9 19:35:23 walden pppd[1000]: Using interface ppp0
Oct  9 19:35:23 walden pppd[1000]: Connect: ppp0 <--> /dev/ttyp2
Oct  9 19:35:23 walden pppd[1000]: sent [LCP ConfReq id=0x1 <auth chap MD5>
<magic 0x693fecf7> <pcomp> <accomp>]
Oct  9 19:35:50 walden last message repeated 9 times
Oct  9 19:35:53 walden pppd[1000]: LCP: timeout sending Config-Requests
Oct  9 19:35:53 walden pppd[1000]: Connection terminated.
Oct  9 19:35:54 walden pppd[1000]: Exit.
Oct  9 19:35:54 walden pptpd[999]: GRE: read(fd=4,buffer=6514,len=8196) from
PTY failed: status = 0 error = No error
Oct  9 19:35:54 walden pptpd[999]: CTRL: PTY read or GRE write failed
(pty,gre)=(4,5)
Oct  9 19:35:54 walden pptpd[999]: CTRL: Client 195.36.211.41 control
connection finished
Oct  9 19:35:54 walden pptpd[999]: CTRL: Exiting now
Oct  9 19:35:54 walden pptpd[994]: MGR: Reaped child 999

As you can see, pptpd gets started up. It just seems then, though, that the LCP
packets from the local machine aren't getting sent to the client, and that
requests from the client aren't coming in. I don't know if this has anything to
do with the local and remote IP addresses assigned to pptpd or not.

I do know that I am not seeing the IP address 192.168.0.235 show up in my ARP
table. I'm not sure if I should see it show up or not.

Perhaps the problem is that the pppd doesn't like being run on the other side
of a PTY? I don't think so, but I don't have any proof.

Any thoughts?