Vpn pptp mppe not working

magonick · 2017-06-22 21:00:47

Hello everybody,
I am having issues with my vpn connection to the lab vpn. It used to work a while ago, but after upgrading it stopped working. Right now I can connect to the vpn but I have no internet connection and I can't ssh to my workstation. Everything works fine on Ubuntu, so I assume that the problem is on my side.
I configured everything with network manager, but to debug I run the following commands

sudo pptpsetup --create test --server <VPN_ADDR> --username <UNAME> --encrypt
sudo pon test debug dump logfd 2 nodetach

The output of the second command looks like

pppd options in effect:
debug		# (from command line)
nodetach		# (from command line)
logfd 2		# (from command line)
dump		# (from command line)
noauth		# (from /etc/ppp/peers/test)
name an4915		# (from /etc/ppp/peers/test)
remotename test		# (from /etc/ppp/peers/test)
		# (from /etc/ppp/peers/test)
pty pptp <VPN_ADDR>--nolaunchpppd		# (from /etc/ppp/peers/test)
crtscts		# (from /etc/ppp/options)
		# (from /etc/ppp/options)
asyncmap 0		# (from /etc/ppp/options)
lcp-echo-failure 4		# (from /etc/ppp/options)
lcp-echo-interval 30		# (from /etc/ppp/options)
hide-password		# (from /etc/ppp/options)
ipparam test		# (from /etc/ppp/peers/test)
proxyarp		# (from /etc/ppp/options)
nobsdcomp		# (from /etc/ppp/peers/test)
nodeflate		# (from /etc/ppp/peers/test)
require-mppe-128		# (from /etc/ppp/peers/test)
noipx		# (from /etc/ppp/options)
using channel 1
Using interface ppp0
Connect: ppp0 <--> /dev/pts/1
Error: either "to" is duplicate, or "uid" is a garbage.
sent [LCP ConfReq id=0x1 <asyncmap 0x0> <magic 0x72c3eee5> <pcomp> <accomp>]
rcvd [LCP ConfReq id=0x1 <asyncmap 0x0> <auth chap MS-v2> <magic 0x567e3b4c> <pcomp> <accomp>]
sent [LCP ConfAck id=0x1 <asyncmap 0x0> <auth chap MS-v2> <magic 0x567e3b4c> <pcomp> <accomp>]
rcvd [LCP ConfAck id=0x1 <asyncmap 0x0> <magic 0x72c3eee5> <pcomp> <accomp>]
sent [LCP EchoReq id=0x0 magic=0x72c3eee5]
rcvd [LCP EchoReq id=0x0 magic=0x567e3b4c]
sent [LCP EchoRep id=0x0 magic=0x72c3eee5]
rcvd [CHAP Challenge id=0x18 <71fc3615c4f1df40d816f67921bbfc7b>, name = "pptpd"]
added response cache entry 0
sent [CHAP Response id=0x18 <feb050f063d130ca912c86c216ddf67600000000000000003e47cb3424e0ea5dd278051558146c91dd6d84c710f60b9b00>, name = "an4915"]
rcvd [LCP EchoRep id=0x0 magic=0x567e3b4c]
rcvd [CHAP Success id=0x18 "S=AD810E2D53B78A5FE156292362D7F01E1C0C1990"]
response found in cache (entry 0)
CHAP authentication succeeded
sent [CCP ConfReq id=0x1 <mppe +H -M +S -L -D -C>]
rcvd [CCP ConfReq id=0x1 <mppe +H -M +S +L -D -C>]
sent [CCP ConfNak id=0x1 <mppe +H -M +S -L -D -C>]
rcvd [CCP ConfAck id=0x1 <mppe +H -M +S -L -D -C>]
rcvd [CCP ConfReq id=0x2 <mppe +H -M +S -L -D -C>]
sent [CCP ConfAck id=0x2 <mppe +H -M +S -L -D -C>]
MPPE 128-bit stateless compression enabled
sent [IPCP ConfReq id=0x1 <compress VJ 0f 01> <addr 0.0.0.0>]
rcvd [IPCP ConfReq id=0x1 <compress VJ 0f 01> <addr [IPADDR1]>]
sent [IPCP ConfAck id=0x1 <compress VJ 0f 01> <addr [IPADDR1]>]
rcvd [IPCP ConfNak id=0x1 <addr [IPADDR2]>]
sent [IPCP ConfReq id=0x2 <compress VJ 0f 01> <addr  [IPADDR2]>]
rcvd [IPCP ConfAck id=0x2 <compress VJ 0f 01> <addr  [IPADDR2]>]
Cannot determine ethernet address for proxy ARP
local  IP address  [IPADDR2]
remote IP address  [IPADDR1]
Script /etc/ppp/ip-up started (pid 2834)
Script /etc/ppp/ip-up finished (pid 2834), status = 0x0
Modem hangup
Connect time 2.1 minutes.
Sent 69098631 bytes, received 0 bytes.
Script /etc/ppp/ip-down started (pid 2873)
MPPE disabled
sent [LCP TermReq id=0x2 "MPPE disabled"]
Connection terminated.
Script pptp <VPN_ADDR> --nolaunchpppd finished (pid 2820), status = 0x0
Script /etc/ppp/ip-down finished (pid 2873), status = 0x0

I am a bit lost to be honest a this point. Could you please help me to debug this?
Cheers!

R00KIE · 2017-06-22 21:43:01

Do you have any firewall configured in your computer? Can you narrow down the time window when things stopped working?

magonick · 2017-06-23 07:40:40

Hi,
no firewall configured. The update might be around march.

R00KIE · 2017-06-23 11:51:24

That is a big timeframe. Check your pacman log for what you have updated around that time and see if anything related to pptp was updated or check if anything else looks like a candidate for being the culprit of things not working.

That said, if you can connect to the vpn it might not be a vpn problem, maybe just a route problem. Post the output of 'ip route' before and after connecting to the vpn, maybe someone can spot a problem. Also check dmesg and the journal for any warnings or errors while you connect as those might also provide clues as to what is the problem.

magonick · 2017-06-23 14:07:06

So, I checked pacman's log and there is nothing suspicious.
here is the ouput of ip route before connecting to the vpn

default via 192.168.0.1 dev wlp3s0 proto static metric 600 
192.168.0.0/24 dev wlp3s0 proto kernel scope link src 192.168.0.4 metric 600

and after

default dev ppp0 proto static scope link metric 50 
default via 192.168.0.1 dev wlp3s0 proto static metric 600 
192.168.0.0/24 dev wlp3s0 proto kernel scope link src 192.168.0.4 metric 600 
192.168.0.1 dev wlp3s0 proto static scope link metric 600 
193.61.68.227 dev ppp0 proto kernel scope link src 129.31.240.186 metric 50

also another collegue is affected by the issue.
in dmesg I did not find any warning whatsoever.

R00KIE · 2017-06-23 15:43:39

Maybe someone changed the configuration on the server side. I'm not an expert at networking but I'd say that "default dev ppp0 proto static scope link metric 50" has priority over "default via 192.168.0.1 dev wlp3s0 proto static metric 600".

Can you at least ping the server? Lets see if someone else more versed in networking chimes in and provides any tips.

magonick · 2017-06-23 15:48:14

I tried to ping but nothing happens. I don't have internet access neither. If something had changed on the server side I would have expected to impact also on Ubuntu and Windows. Am I wrong?

R00KIE · 2017-06-23 16:32:43

magonick wrote:

If something had changed on the server side I would have expected to impact also on Ubuntu and Windows. Am I wrong?

Yes, you are correct, so that option is of the table.

You can try to compare the routing table between ubuntu that works and arch that doesn't work, if it is the same then the problem is something else. Don't forget to check dmesg and your journal.

Arch Linux

#1 2017-06-22 21:00:47

Vpn pptp mppe not working

#2 2017-06-22 21:43:01

Re: Vpn pptp mppe not working

#3 2017-06-23 07:40:40

Re: Vpn pptp mppe not working

#4 2017-06-23 11:51:24

Re: Vpn pptp mppe not working

#5 2017-06-23 14:07:06

Re: Vpn pptp mppe not working

#6 2017-06-23 15:43:39

Re: Vpn pptp mppe not working

#7 2017-06-23 15:48:14

Re: Vpn pptp mppe not working

#8 2017-06-23 16:32:43

Re: Vpn pptp mppe not working

Board footer