Problems connecting to VPN with PPTP

Brevity · 03-12-2005, 01:35 AM

Hello,

I recently installed Fedora Core 3 and I am having some trouble connecting to my VPN at work. I am behind a router on my home network and I would like to VPN into the corporate network. All of my connection settings should be correct, but there must still be a problem with my configuration.

I am using PPTP and with debug messages turned on this is the output I get:

Code:

Using interface ppp0
pptpconfig: monitoring interface ppp0
Connect: ppp0 <--> /dev/pts/3
sent [LCP ConfReq id=0x1 <asyncmap 0x0> <magic 0x4883f004> <pcomp> <accomp>]
rcvd [LCP ConfAck id=0x1 <asyncmap 0x0> <magic 0x4883f004> <pcomp> <accomp>]
sent [LCP ConfReq id=0x1 <asyncmap 0x0> <magic 0x4883f004> <pcomp> <accomp>]
rcvd [LCP ConfAck id=0x1 <asyncmap 0x0> <magic 0x4883f004> <pcomp> <accomp>]
rcvd [LCP ConfReq id=0xe5 <mru 1500> <asyncmap 0xa0000> <auth chap MS-v2> <magic 0x3f64d4d9> <pcomp> <accomp>]
sent [LCP ConfAck id=0xe5 <mru 1500> <asyncmap 0xa0000> <auth chap MS-v2> <magic 0x3f64d4d9> <pcomp> <accomp>]
rcvd [CHAP Challenge id=0x2 <e45cd546ec6aeb27dab19c096aee52ce>, name = "omitted for this post"]
sent [CHAP Response id=0x2 <6d1460fdeef4ca034157c7b4ecf8f65e00000000000000004b6f831b445ed1e841436557a3ffe31a08ad871cc93d779800>, name = "omitted for this post"]
rcvd [LCP ConfReq id=0x54 <mru 1500> <asyncmap 0xa0000> <auth chap MS> <magic 0x5f5a09d9> <pcomp> <accomp>]
sent [LCP ConfReq id=0x2 <asyncmap 0x0> <magic 0x53159f18> <pcomp> <accomp>]
sent [LCP ConfNak id=0x54 <auth chap MS-v2>]
rcvd [LCP ConfAck id=0x2 <asyncmap 0x0> <magic 0x53159f18> <pcomp> <accomp>]
rcvd [LCP TermReq id=0x55]
sent [LCP TermAck id=0x55]
Script pptp vpn-hostname-omitted-for-this-post  --nolaunchpppd  finished (pid 13512), status = 0x0
Modem hangup
Connection terminated.
# route -n (after pppd exit)
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
192.168.1.0     0.0.0.0         255.255.255.0   U     0      0        0 eth0
169.254.0.0     0.0.0.0         255.255.0.0     U     0      0        0 eth0
0.0.0.0         192.168.1.1     0.0.0.0         UG    0      0        0 eth0
pptpconfig: pppd process terminated by signal 16 (failed)
pptpconfig: SIGUSR1
# route -n (after completion)
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
192.168.1.0     0.0.0.0         255.255.255.0   U     0      0        0 eth0
169.254.0.0     0.0.0.0         255.255.0.0     U     0      0        0 eth0

I'm confused about about a couple of things. Shouldn't pptp be monitoring my eth0 interface and not the ppp0 inteface? Running ifconfig -i ppp0 comes back with a complaint about that device not existing. Also, it looks like I am sending and receiving packets, so why is the connection being terminated immediately?

Any help would be greatly appreciated!

Brevity · 03-12-2005, 05:25 PM

Anyone have ANY suggestions at all? I've read other threads about VPN problems but haven't seen anything regarding my specific situation. Please help me.

Brevity · 03-12-2005, 10:44 PM

Well I'm a little miffed that no one on this board was able to even make a suggestion as to what my problem was. However, since I was able to resolve it myself, I will post the problem and solution for anyone else with a similar error.

In the log I posted in my original post, these were the important messages:

Code:

rcvd [LCP ConfReq id=0x54 <mru 1500> <asyncmap 0xa0000> <auth chap MS> <magic 0x5f5a09d9> <pcomp> <accomp>]
sent [LCP ConfNak id=0x54 <auth chap MS-v2>]

The ConfNak message basically means that one of the option values I received from the destination server in the ConfReq was not what my configuration wanted. The value returned with the ConfNak message is what my configuration wants to use. In this case, the PPTP server I was trying to connect to wanted to use <auth chap MS>, but my options.pptp file was only allowing for <auth chap MS-v2> to be used. To fix the problem, all I had to do was go into my /etc/ppp/options.pptp file and comment out the following line:

refuse-mschap

After commenting this out, the auth chap MS value was accepted by my client and all was good.