CODEWITHSUNDEEP
linuxroutesvpsarchlinuxpptp
scturtle
scturtle

Reputation: 17

PPTP server on archlinux, KVM VPS, client never received packages

I'm trying to set up PPTP server on KVM VPS of DigitalOcean. My configurations are following.

/etc/iptables/iptables.rules:

*nat
-A POSTROUTING -o eth0 -j MASQUERADE
COMMIT

/etc/pptpd.conf (the localip is server IP, 45.55.20.125 or 104.236.158.120 in following servers):

option /etc/ppp/pptpd-options
logwtmp
localip SERVER_IP
remoteip 10.1.0.1-10

/etc/ppp/pptpd-options:

name pptpd
refuse-pap
refuse-chap
refuse-mschap
require-mschap-v2
require-mppe-128
proxyarp
nodefaultroute
lock
nobsdcomp
novj
novjccomp
nologfd
ms-dns 8.8.8.8
ms-dns 8.8.4.4

/etc/sysctl.conf:

net.ipv4.ip_forward=1

It works with Debian OS (server IP: 45.55.20.125). Informations are following when I ping 8.8.8.8 on client:

root@test:~# route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         45.55.0.1       0.0.0.0         UG    0      0        0 eth0
10.1.0.1        0.0.0.0         255.255.255.255 UH    0      0        0 ppp0
10.134.0.0      0.0.0.0         255.255.0.0     U     0      0        0 eth1
45.55.0.0       0.0.0.0         255.255.224.0   U     0      0        0 eth0

root@test:~# tcpdump -n -i eth0 icmp
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth0, link-type EN10MB (Ethernet), capture size 262144 bytes
04:37:22.566596 IP 45.55.20.125 > 8.8.8.8: ICMP echo request, id 64781, seq 0, length 64
04:37:22.569073 IP 8.8.8.8 > 45.55.20.125: ICMP echo reply, id 64781, seq 0, length 64
04:37:23.570903 IP 45.55.20.125 > 8.8.8.8: ICMP echo request, id 64781, seq 1, length 64
04:37:23.573515 IP 8.8.8.8 > 45.55.20.125: ICMP echo reply, id 64781, seq 1, length 64
04:37:24.571255 IP 45.55.20.125 > 8.8.8.8: ICMP echo request, id 64781, seq 2, length 64
04:37:24.573913 IP 8.8.8.8 > 45.55.20.125: ICMP echo reply, id 64781, seq 2, length 64

root@test:~# tcpdump -n -i ppp0 icmp
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on ppp0, link-type LINUX_SLL (Linux cooked), capture size 262144 bytes
04:37:22.566558 IP 10.1.0.1 > 8.8.8.8: ICMP echo request, id 64781, seq 0, length 64
04:37:22.569095 IP 8.8.8.8 > 10.1.0.1: ICMP echo reply, id 64781, seq 0, length 64
04:37:23.570871 IP 10.1.0.1 > 8.8.8.8: ICMP echo request, id 64781, seq 1, length 64
04:37:23.573543 IP 8.8.8.8 > 10.1.0.1: ICMP echo reply, id 64781, seq 1, length 64
04:37:24.571224 IP 10.1.0.1 > 8.8.8.8: ICMP echo request, id 64781, seq 2, length 64

But after I converted one Debian into Archlinux (server IP: 104.236.158.120) with digitalocean-debian-to-arch. When I ping 8.8.8.8 on client:

> ip route
default via 104.236.128.1 dev eth0  proto static
10.1.0.1 dev ppp0  proto kernel  scope link  src 104.236.158.120
104.236.128.0/18 dev eth0  proto kernel  scope link  src 104.236.158.120

> sudo tcpdump -n -i eth0 icmp
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth0, link-type EN10MB (Ethernet), capture size 262144 bytes
16:55:28.352582 IP 104.236.158.120 > 8.8.8.8: ICMP echo request, id 51470, seq 10, length 64
16:55:28.354295 IP 8.8.8.8 > 104.236.158.120: ICMP echo reply, id 51470, seq 10, length 64
16:55:29.357393 IP 104.236.158.120 > 8.8.8.8: ICMP echo request, id 51470, seq 11, length 64
16:55:29.359129 IP 8.8.8.8 > 104.236.158.120: ICMP echo reply, id 51470, seq 11, length 64
16:55:30.361901 IP 104.236.158.120 > 8.8.8.8: ICMP echo request, id 51470, seq 12, length 64
16:55:30.363614 IP 8.8.8.8 > 104.236.158.120: ICMP echo reply, id 51470, seq 12, length 64

> sudo tcpdump -n -i ppp0 icmp
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on ppp0, link-type LINUX_SLL (Linux cooked), capture size 262144 bytes
16:55:24.338226 IP 10.1.0.1 > 8.8.8.8: ICMP echo request, id 51470, seq 6, length 64
16:55:25.343537 IP 10.1.0.1 > 8.8.8.8: ICMP echo request, id 51470, seq 7, length 64
16:55:26.347889 IP 10.1.0.1 > 8.8.8.8: ICMP echo request, id 51470, seq 8, length 64

There are no "8.8.8.8 > 10.1.0.1" packages and I cannot figure out why. What could be the problem?

Upvotes: -2

Views: 285

Answers (1)

scturtle
scturtle

Reputation: 17

Oh, I get it now. Forwarding of interface eth0 need to be enabled.

# echo 1 > /proc/sys/net/ipv4/conf/eth0/forwarding

Upvotes: 0

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