Hi everyone,
I'm running a PPTP VPN Server for almost 4 years now. This server is
running in a Debian Linux (unstable).
The configuration for the last 1 year and a half was the following:
Computer 2x Intel Xeon 2.6GHz and 512MB RAM
Linux v2.6.11.6 (vanilla) with MPPE patch
Debian distribution with the following packages
- pppd 2.4.3-20050321
- libradius1 0.3.2-8
- radiusclient1 0.3.2-8
With this configuration I had reach a peek of aprox. 600 hundred PPTP
connections simultaneously. The computer gets heavy loaded doing MPPE
compression/decompression with 40Mbits/sec of PPP traffic but didn't have
any problem with this setup. The authentication process is using a pool of
RADIUS servers.
This machine is also a firewall, and now a new feature was needed: PPTP
VPN connections from the inside.
The problem:
After the upgrade to a Linux v2.6.15.4 (vanilla) with no patches to use
the new "ip_conntrack_pptp" module, I started to get "pppd" processes
hanging in "S" state and consuming CPU power.
---- Here is a bit of debug commands ----
machine:# strace -p 18859
Process 18859 attached - interrupt to quit
ioctl(8, TIOCSETD (Issued Ctrl+C here after a few seconds)<unfinished ...>
machine:# ps aux | grep 18859
root 18859 2.1 0.2 2696 1360 ? S 09:52 17:27
/usr/sbin/pppd local file /etc/ppp/options.pptpd 115200 10.2.255.254:
machine:# ps ax | grep 18859
18859 ? S 17:30 /usr/sbin/pppd local file /etc/ppp/options.pptpd
115200 10.2.255.254:10.2.0.71 ipparam 10.1.7.232 plugin
/usr/lib/pptpd/pptpd-logwtmp.so pptpd-original-ip 10.1.7.232
machine:# lsof -p 18859
COMMAND PID USER FD TYPE DEVICE SIZE NODE NAME
pppd 18859 root cwd DIR 9,1 4096 2 /
pppd 18859 root rtd DIR 9,1 4096 2 /
pppd 18859 root txt REG 9,1 265880 4424041 /usr/sbin/pppd
pppd 18859 root mem REG 0,0 0 [heap] (stat: No
such file or directory)
pppd 18859 root mem REG 9,1 64924 1720713
/lib/tls/libresolv-2.3.2.so
pppd 18859 root mem REG 9,1 13976 1720706
/lib/tls/libnss_dns-2.3.2.so
pppd 18859 root mem REG 9,2 147456 711080
/var/run/pppd2.tdb
pppd 18859 root mem REG 9,1 47024 5095932
/usr/lib/pppd/2.4.3/radius.so
pppd 18859 root mem REG 9,1 34748 1720707
/lib/tls/libnss_files-2.3.2.so
pppd 18859 root mem REG 9,1 33440 1720709
/lib/tls/libnss_nis-2.3.2.so
pppd 18859 root mem REG 9,1 73304 1720704
/lib/tls/libnsl-2.3.2.so
pppd 18859 root mem REG 9,1 28616 1720705
/lib/tls/libnss_compat-2.3.2.so
pppd 18859 root mem REG 9,1 1254468 1720699
/lib/tls/libc-2.3.2.so
pppd 18859 root mem REG 9,1 113040 3621129
/usr/lib/libpcap.so.0.7.1
pppd 18859 root mem REG 9,1 9872 1720701
/lib/tls/libdl-2.3.2.so
pppd 18859 root mem REG 9,1 30360 4637043
/lib/libpam.so.0.76
pppd 18859 root mem REG 9,1 18876 1720700
/lib/tls/libcrypt-2.3.2.so
pppd 18859 root mem REG 9,1 4272 3621647
/usr/lib/pptpd/pptpd-logwtmp.so
pppd 18859 root mem REG 9,1 90024 4637078 /lib/ld-2.3.2.so
pppd 18859 root 0u CHR 136,64 66 /dev/pts/64
pppd 18859 root 1u CHR 136,64 66 /dev/pts/64
pppd 18859 root 2u CHR 1,3 4472977 /dev/null
pppd 18859 root 3u unix 0xd5341500 34918748 socket
pppd 18859 root 4u CHR 1,3 4472977 /dev/null
pppd 18859 root 5u sock 0,4 34918753 can't identify
protocol
pppd 18859 root 6u sock 0,4 34918754 can't identify
protocol
pppd 18859 root 7u REG 9,2 147456 711080
/var/run/pppd2.tdb
pppd 18859 root 8u CHR 136,64 66 /dev/pts/64
pppd 18859 root 9u CHR 108,0 4474356 /dev/ppp
pppd 18859 root 10u CHR 108,0 4474356 /dev/ppp
------ End of debug info ----
Every day I have about 5 new "pppd" processes hanging in this state.
I upgraded to a Linux 2.6.16.16 with no patches and the "ip_conntrack_pptp"
enable. Every other piece of software remains the same. The problem is the
same. I still have compiled a Kernel with no "ip_conntrack_pptp" to see this
was causing the problem but appears not to be the case.
This is kernel config:
#
# Wan interfaces
#
# CONFIG_WAN is not set
# CONFIG_FDDI is not set
# CONFIG_HIPPI is not set
CONFIG_PPP=y
# CONFIG_PPP_MULTILINK is not set
# CONFIG_PPP_FILTER is not set
CONFIG_PPP_ASYNC=y
CONFIG_PPP_SYNC_TTY=y
CONFIG_PPP_DEFLATE=y
CONFIG_PPP_BSDCOMP=y
CONFIG_PPP_MPPE=y
# CONFIG_PPPOE is not set
# CONFIG_SLIP is not set
# CONFIG_SHAPER is not set
# CONFIG_NETCONSOLE is not set
# CONFIG_NETPOLL is not set
# CONFIG_NET_POLL_CONTROLLER is not set
------------------------------------------------------------------------------------------------------
Anyone else has this problem?
Best Regards,
Jorge Matias
CIIST - Centro de Informática do
Instituto Superior Técnico
Universidade Técnica de Lisboa
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