How to access remote lan machines through a ipsec / xl2ptd vpn (maybe iptables related)
- by Simon
I’m trying to do the setup of a IPSEC / XL2TPD VPN for our office, and I’m having some problems accessing the remote local machines after connecting to the VPN.
I can connect, and I can browse Internet sites trough the VPN, but as said, I’m unable to connect or even ping the local ones.
My Network setup is something like this:
INTERNET eth0 ROUTER / VPN eth2 LAN
These are some traceroutes behind the VPN:
traceroute to google.com (173.194.78.94), 64 hops max, 52 byte packets
1 192.168.1.80 (192.168.1.80) 74.738 ms 71.476 ms 70.123 ms
2 10.35.192.1 (10.35.192.1) 77.832 ms 77.578 ms 77.865 ms
3 10.47.243.137 (10.47.243.137) 78.837 ms 85.409 ms 76.032 ms
4 10.47.242.129 (10.47.242.129) 78.069 ms 80.054 ms 77.778 ms
5 10.254.4.2 (10.254.4.2) 86.174 ms
10.254.4.6 (10.254.4.6) 85.687 ms
10.254.4.2 (10.254.4.2) 85.664 ms
traceroute to 192.168.1.3 (192.168.1.3), 64 hops max, 52 byte packets
1 * * *
2 *traceroute: sendto: No route to host
traceroute: wrote 192.168.1.3 52 chars, ret=-1
*traceroute: sendto: Host is down
traceroute: wrote 192.168.1.3 52 chars, ret=-1
*
traceroute: sendto: Host is down
3 traceroute: wrote 192.168.1.3 52 chars, ret=-1
*traceroute: sendto: Host is down
traceroute: wrote 192.168.1.3 52 chars, ret=-1
These are my iptables rules:
iptables -A INPUT -i lo -j ACCEPT
iptables -A INPUT -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT
# allow lan to router traffic
iptables -A INPUT -s 192.168.1.0/24 -i eth2 -j ACCEPT
# ssh
iptables -A INPUT -p tcp --dport ssh -j ACCEPT
# vpn
iptables -A INPUT -p 50 -j ACCEPT
iptables -A INPUT -p ah -j ACCEPT
iptables -A INPUT -p udp --dport 500 -j ACCEPT
iptables -A INPUT -p udp --dport 4500 -j ACCEPT
iptables -A INPUT -p udp --dport 1701 -j ACCEPT
# dns
iptables -A INPUT -s 192.168.1.0/24 -p tcp --dport 53 -j ACCEPT
iptables -A INPUT -s 192.168.1.0/24 -p udp --dport 53 -j ACCEPT
iptables -t nat -A POSTROUTING -j MASQUERADE
# logging
iptables -I INPUT 5 -m limit --limit 1/min -j LOG --log-prefix "iptables denied: " --log-level 7
# block all other traffic
iptables -A INPUT -j DROP
And here are some firewall log lines:
Dec 6 11:11:57 router kernel: [8725820.003323] iptables denied: IN=ppp0 OUT= MAC= SRC=192.168.1.81 DST=192.168.1.3 LEN=60 TOS=0x00 PREC=0x00 TTL=255 ID=62174 PROTO=UDP SPT=61910 DPT=53 LEN=40
Dec 6 11:12:29 router kernel: [8725852.035826] iptables denied: IN=ppp0 OUT= MAC= SRC=192.168.1.81 DST=224.0.0.1 LEN=44 TOS=0x00 PREC=0x00 TTL=1 ID=15344 PROTO=UDP SPT=56329 DPT=8612 LEN=24
Dec 6 11:12:36 router kernel: [8725859.121606] iptables denied: IN=ppp0 OUT= MAC= SRC=192.168.1.81 DST=224.0.0.1 LEN=44 TOS=0x00 PREC=0x00 TTL=1 ID=11767 PROTO=UDP SPT=63962 DPT=8612 LEN=24
Dec 6 11:12:44 router kernel: [8725866.203656] iptables denied: IN=ppp0 OUT= MAC= SRC=192.168.1.81 DST=224.0.0.1 LEN=44 TOS=0x00 PREC=0x00 TTL=1 ID=11679 PROTO=UDP SPT=57101 DPT=8612 LEN=24
Dec 6 11:12:51 router kernel: [8725873.285979] iptables denied: IN=ppp0 OUT= MAC= SRC=192.168.1.81 DST=224.0.0.1 LEN=44 TOS=0x00 PREC=0x00 TTL=1 ID=39165 PROTO=UDP SPT=62625 DPT=8612 LEN=24
I’m pretty sure that the problem should be related with iptables, but after trying a lot of different confs, I was unable to find the right one.
Any help will be greetly appreciated ;). Kind regards, Simon.
EDIT:
This is my route table:
default 62.43.193.33.st 0.0.0.0 UG 100 0 0 eth0
62.43.193.32 * 255.255.255.224 U 0 0 0 eth0
192.168.1.0 * 255.255.255.0 U 0 0 0 eth2
192.168.1.81 * 255.255.255.255 UH 0 0 0 ppp0
