[pptp-server] Clogged Tunnel!

[Cowles, Steve]

> -----Original Message-----
> From: Luke Myers [mailto:lukekalemyers at yahoo.com]
> Sent: Wednesday, March 21, 2001 9:10 PM
> To: pptp-server at lists.schulte.org
> Subject: [pptp-server] Clogged Tunnel!
> 
> 
> Hi Folks,
> 
> I have a three exellent looking PPTP tunnels between one Redhat 7.0
> box and three different Win98 clients.  However, one tunnel will not 
> pass any data, not even a ping! I am using:
> 
> -- PoPToP v1.0.0
> -- Linux 2.2.16-22
> -- pppd 2.3.11
> -- 128bit stateless encryption
> -- 128bit Dial-up Networking upgrades
> -- Windows 98
> 
> Following is the log output for a good connection:
> 
> Mar 21 21:40:42 ds pptpd[30394]: CTRL: Client 208.164.103.206 control
> connection started
> Mar 21 21:40:45 ds pptpd[30394]: CTRL: Starting call (launching pppd,
> opening GRE)
> Mar 21 21:40:45 ds pppd[30395]: pppd 2.3.11 started by root, uid 0
> Mar 21 21:40:45 ds pppd[30395]: Using interface ppp2
> Mar 21 21:40:45 ds pppd[30395]: Connect: ppp2 <--> /dev/pts/1
> Mar 21 21:40:46 ds pppd[30395]: MSCHAP-v2 peer authentication 
> succeeded for OUR-WORKGROUP\\luke
> Mar 21 21:40:47 ds pppd[30395]: Cannot determine ethernet address for
proxy ARP

Although the above error is not the source of the problem you describe, you
really need to resolve the proxy ARP error listed above. On a properly
configured PPTP server, you should see an entry like:

Mar 12 16:53:52 excelsior pppd[767]: found interface eth0 for proxy arp

in your log files. 

> Mar 21 21:40:47 ds pppd[30395]: local  IP address 192.168.1.1
> Mar 21 21:40:47 ds pppd[30395]: remote IP address 192.168.1.5
> Mar 21 21:40:47 ds pppd[30395]: MPPE 128 bit, stateless compression
enabled
> Mar 21 21:44:45 ds pppd[29457]: LCP terminated by peer
> Mar 21 21:44:47 ds pptpd[29456]: CTRL: Error with select(), quitting
> Mar 21 21:44:47 ds pptpd[29456]: CTRL: Client 24.48.231.141 control
> connection finished
> Mar 21 21:44:47 ds pppd[29457]: Modem hangup
> Mar 21 21:44:47 ds pppd[29457]: Connection terminated.
> Mar 21 21:44:47 ds pppd[29457]: Connect time 286.0 minutes.
> Mar 21 21:44:47 ds pppd[29457]: Sent 4307228 bytes, received 1957577
bytes.
> Mar 21 21:44:47 ds pppd[29457]: Exit.
> 
> 
> Following is the first part of the log output for a connection that
> looks successful but cannot move any data:
> 
> Mar 21 20:32:21 ds pptpd[30114]: CTRL: Client 24.48.139.165 control
> connection started
> Mar 21 20:32:21 ds pptpd[30114]: CTRL: Starting call (launching pppd,
> opening GRE)
> Mar 21 20:32:21 ds pppd[30115]: pppd 2.3.11 started by root, uid 0
> Mar 21 20:32:21 ds pppd[30115]: Using interface ppp0
> Mar 21 20:32:21 ds pppd[30115]: Connect: ppp0 <--> /dev/pts/0
> Mar 21 20:32:22 ds pppd[30115]: MSCHAP-v2 peer authentication 
> succeeded for our-workgroup\\ldke$%^*
> Mar 21 20:32:22 ds pppd[30115]: Cannot determine ethernet address for
proxy ARP

Same comment as above.

> Mar 21 20:32:22 ds pppd[30115]: local  IP address 192.168.1.1
> Mar 21 20:32:22 ds pppd[30115]: remote IP address 192.168.1.3
> Mar 21 20:32:22 ds pppd[30115]: MPPE 128 bit, stateless 
> compression enabled
> 
> Here is my /etc/ppp/options.pptp file:
> 
> auth
> lock
> debug
> proxyarp
> +chap
> +chapms
> +chapms-v2
> mppe-40
> mppe-128
> mppe-stateless
> ms-wins 192.168.1.1
> 
> Here are the essentials from my /etc/pptpd.conf file:
> 
> option /etc/ppp/options.pptp
> debug
> localip 192.168.1.1
> remoteip 192.168.1.2-254
> 
> This problem is mystifying because:
> 
> I can ping fine directly between the affected Win98 box and the Linux
> server,

Huh!! Now I'm mystified. Earlier you stated that this system could not pass
any data through the tunnel. Now your stating that you can ping the PPTP
server. Am I missing something?

> 
> Win98 connection shows nothing wrong or abnormal about the connection,
> 
> The Linux log files show no difference between the good connections
> and the bad connection, and
> 
> Disabling compression and encryption though Windows does not help.
> 

Your config files look OK with the exception of the proxy arp error. The
proxy arp errors can usually be fixed by assigning IP addresses in
pptpd.conf (local/remote) that are within the network address range of the
PPTP servers LAN (like eth0 or eth1). If thats not an option, then consider
using ip aliasing to bind the 192.168.1.0/24 LAN to either eth0 or eth1
interface. Checkout the kernel source documentation directory
/usr/src/linux/Documentation/alias.txt for info on ip aliasing.

As for the Win98 system that is unable to send/receive data, consider
reloading Microsoft's Dialup Networking. FWIW: Other list members have
reported that reloading DUN fixed strange problems. Check this lists
archives for the link @ Microsoft to download the latest DUN package.

Good Luck!
Steve Cowles