When pppd is running as installed, but sometimes pppd does not work and showing warning message - discarding bogus packet: pppd is dropping its packet intentionally, so VPN is actually not working from that time. The workaround I can do is just disconnect the VPN and reconnect.
I just checked system progress by
ps aux --sort | grep ppp
and verified pppd is correctly working as planned as below:
root 3185 0.0 0.0 80708 1632 ? Ss Apr22 0:00 pppd call linuxconfig root 3186 0.0 0.0 13180 1380 ? S Apr22 0:17 pptp u************.com --nolaunchpppd root 3203 0.0 0.0 12812 628 ? S Apr22 0:00 pptp u************.com --nolaunchpppd
I also checked /var/log/messages and found below error messages - it looks like something is coming, but ignoring its packet by pptpd.
Apr 23 08:32:21 ***** pptp[3186]: anon warn[decaps_gre:pptp_gre.c:439]: discarding bogus packet 118939 (expecting 99092) Apr 23 08:32:23 ***** pptp[3186]: anon warn[decaps_gre:pptp_gre.c:439]: discarding bogus packet 118940 (expecting 99092) Apr 23 08:32:23 ***** pptp[3186]: anon warn[decaps_gre:pptp_gre.c:439]: discarding bogus packet 118941 (expecting 99092) Apr 23 08:32:24 ***** pptp[3186]: anon warn[decaps_gre:pptp_gre.c:439]: discarding bogus packet 118942 (expecting 99092) Apr 23 08:32:26 ***** pptp[3186]: anon warn[decaps_gre:pptp_gre.c:439]: discarding bogus packet 118943 (expecting 99092) Apr 23 08:32:28 ***** pptp[3186]: anon warn[decaps_gre:pptp_gre.c:439]: discarding bogus packet 118944 (expecting 99092) Apr 23 08:32:29 ***** pptp[3186]: anon warn[decaps_gre:pptp_gre.c:439]: discarding bogus packet 118945 (expecting 99092) Apr 23 08:32:29 ***** pptp[3186]: anon warn[decaps_gre:pptp_gre.c:439]: discarding bogus packet 118946 (expecting 99092) Apr 23 08:32:31 ***** pptp[3186]: anon warn[decaps_gre:pptp_gre.c:439]: discarding bogus packet 118947 (expecting 99092) Apr 23 08:32:33 ***** pptp[3186]: anon warn[decaps_gre:pptp_gre.c:439]: discarding bogus packet 118948 (expecting 99092) Apr 23 08:32:36 ***** pptp[3186]: anon warn[decaps_gre:pptp_gre.c:439]: discarding bogus packet 118949 (expecting 99092) Apr 23 08:32:40 ***** pptp[3186]: anon warn[decaps_gre:pptp_gre.c:439]: discarding bogus packet 118950 (expecting 99092)
The PPTP setting I use is as following:
vi /etc/ppp/options.pptp
############################################################################### # $Id: options.pptp,v 1.3 2006/03/26 23:11:05 quozl Exp $ # # Sample PPTP PPP options file /etc/ppp/options.pptp # Options used by PPP when a connection is made by a PPTP client. # This file can be referred to by an /etc/ppp/peers file for the tunnel. # Changes are effective on the next connection. See "man pppd". # # You are expected to change this file to suit your system. As # packaged, it requires PPP 2.4.2 or later from http://ppp.samba.org/ # and the kernel MPPE module available from the CVS repository also on # http://ppp.samba.org/, which is packaged for DKMS as kernel_ppp_mppe. ############################################################################### # Lock the port lock # Authentication # We don't need the tunnel server to authenticate itself noauth # We won't do PAP, EAP, CHAP, or MSCHAP, but we will accept MSCHAP-V2 # (you may need to remove these refusals if the server is not using MPPE) refuse-pap refuse-eap refuse-chap refuse-mschap # Compression # Turn off compression protocols we know won't be used nobsdcomp nodeflate # Encryption # (There have been multiple versions of PPP with encryption support, # choose which of the following sections you will use. Note that MPPE # requires the use of MSCHAP-V2 during authentication) # # Note that using PPTP with MPPE and MSCHAP-V2 should be considered # insecure: # http://marc.info/?l=pptpclient-devel&m=134372640219039&w=2 # https://github.com/moxie0/chapcrack/blob/master/README.md # http://technet.microsoft.com/en-us/security/advisory/2743314 # http://ppp.samba.org/ the PPP project version of PPP by Paul Mackarras # ppp-2.4.2 or later with MPPE only, kernel module ppp_mppe.o # If the kernel is booted in FIPS mode (fips=1), the ppp_mppe.ko module # is not allowed and PPTP-MPPE is not available. # {{{ # Require MPPE 128-bit encryption # require-mppe-128 # }}} # http://mppe-mppc.alphacron.de/ fork from PPP project by Jan Dubiec # ppp-2.4.2 or later with MPPE and MPPC, kernel module ppp_mppe_mppc.o # {{{ # Require MPPE 128-bit encryption # mppe required,stateless # }}}
I haven't solved that issue at the moment, and going to update this page when I resolve it.