PPTP Tunneling
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Contents |
Introduction
The configuration below was tested using two WRT54G (Hardware v2.2) and DD-WRT v23 SP1 std.
(Update: The mini version of v23 SP1 may work better than standard, because the free memory will help.)
Note: In v23SP2 Final this configuration does not work. Please check bugtracker ID 0001811
(Missing routes can be added manually with a "ip route add 192.168.x.0/24 dev ppp0" or similar) Have a look at #Fixing routing from server to client network for a script solution. |
The purpose of this setup is to connect to any IP Address on network A or B from network A or B.
- Network A in location "a"
Router A address | 192.168.1.1 |
DHCP range | 192.168.1.100-150 |
Dyndns address | "direccion_de_A.dyndns.org" |
- Network B in location "b"
Router B address | 192.168.2.1 |
DHCP range | 192.168.2.100-150 |
Dyndns address | "direccion_de_B.dyndns.org" |
Configuration
For Both Routers
- Goto "Administration" tab and "Management" sub-tab
- Enable DNSmasq and Local DNS
- Disable Loopback
- Set Maximum Ports:4096
- Set TCP Timeout: 3600
- Set UDP Timeout: 3600
http://img237.imageshack.us/img237/9766/loopbackzs4.jpg
Note: Loopback must be disable because VPN doesn't always work when it is enabled.
http://img366.imageshack.us/img366/1888/ipfiltersettingssq5.jpg
For Router A
Router B > VPN > Router A
- Goto "Administration" tab and "Services" sub-tab
- Enable PPTP Server
- Set "Server IP or DNS Name" to "192.168.1.1"
- Set "Client IP(s)" to "192.168.1.200-250"
- Set "CHAP-Secrets" to "usernameA * passwordA *"
- Apply Changes
Router A > VPN > Router B
- Goto "Administration" tab and "Services" sub-tab
- Enable PPTP Client
- Set "Server IP or DNS Name" to the location of Server B (direccion_de_B.dyndns.org)
- Set "Remote Subnet" to "192.168.2.0"
- Set "Remote Subnet Mask" to 255.255.255.0
- Set "MPPE Encryption" to "mppe required"
- Set "MTU" to 1450
- Set MRU to 1450
- Set Username to usernameB
- Set password to passwordB
- Apply Changes
http://img162.imageshack.us/img162/22/ruteadora6ir.jpg
For Router B
Router A > VPN > Router B
- Goto "Administration" tab and "Services" sub-tab
- Enable PPTP Server
- Set "Server IP or DNS Name" to "192.168.2.1"
- Set "Client IP(s)" to 192.168.2.200-250"
- Set "CHAP-Secrets" to "usernameB * passwordB *"
- Apply Changes
Router B > VPN > Router A
- Goto "Administration" tab and "Services" sub-tab
- Enable PPTP Client
- Set "Server IP or DNS Name" to the location of Server A (direccion_de_A.dyndns.org)
- Set "Remote Subnet" to "192.168.1.0"
- Set "Remote Subnet Mask" to 255.255.255.0
- Set "MPPE Encryption" to "mppe required"
- Set "MTU" to 1450
- Set MRU to 1450
- Set Username to usernameA
- Set password to passwordA
- Apply Changes
http://img73.imageshack.us/img73/4391/ruteadorb3nn.jpg
Notes
- The subnets should not intersect each other (i.e. The third octet of direction IP (192.168.thirdoctet.1) of the network A must be different of the network B.
- The range of Client IP(s) must be outside the range of DHCP clients.
- In the example the IP range that occurred for clients vpn ("Client IP(s)") was 192.168.x.200-250 therefore 51 VPN clients allowed
- This is a whammie if you miss it. Don't forget to enable "PPTP Passthrough" if you are using the SPI firewall as found on the SECURITY tab.
Monitoring
To monitoring and guarantee the connection you can setup Watchdog. The following instructions will setup watchdog to monitor the connection every five minutes (update: works better with 9999 seconds).
On both routers:
- Goto "Administration" tab and "Keep Alive" sub-tab.
- Enable Watchdog
- Set "Interval" to 300
- Set IP Addresses to "192.168.1.200 192.168.2.200"
http://img201.imageshack.us/img201/9416/keepaliveye2.jpg
Final Words
- Some times the connection takes minutes in completing itself (more or less 30 minutes), some times is instantaneous.
- You can check routing table in setup tab, advanced routing subtab, show routing table botton
if there are 6 lines like:
WAN_IP_ADRESS | 255.255.255.255 | 0.0.0.0 | WAN |
192.168.Y.1 | 255.255.255.255 | 0.0.0.0 | WAN |
192.168.X.200 | 255.255.255.255 | 0.0.0.0 | WAN |
192.168.Y.0 | 255.255.255.0 | 0.0.0.0 | WAN |
192.168.X.0 | 255.255.255.0 | 0.0.0.0 | LAN & WLAN |
0.0.0.0 | 0.0.0.0 | WAN_IP_ADRESS | WAN |
Your vpn tunnel must be established and working!!!
Fixing routing from server to client network
To fix the routing problem stated above you can try the folowing script as a startup script:
CLIENTIP=xxx.xxx.xxx.xxx CLIENTNETWORK=192.168.0.0/24 echo "if [ $CLIENTIP == \$6 ]; then" >> /tmp/pptpd/ip-up echo " /usr/sbin/ip route add $CLIENTNETWORK dev \$1" >> /tmp/pptpd/ip-up echo "fi" >> /tmp/pptpd/ip-up echo "if [ $CLIENTIP == \$6 ]; then" >> /tmp/pptpd/ip-down echo " /usr/sbin/ip route delete $CLIENTNETWORK dev \$1" >> /tmp/pptpd/ip-down echo "fi" >> /tmp/pptpd/ip-down
Change xxx.xxx.xxx.xxx to the public ip address of the client. Change 192.168.0.0/24 to the subnet range of the client.
Useful Links
http://www.dd-wrt.com/phpBB2/viewtopic.php?t=1767 http://www.dd-wrt.com/dd-wrtv2/bugtracker/
PPTP_Server_Configuration HOW_TO_configure_a_WINDOWS_BOX_to_make_a_VPN_Connection_to_linksys