PPTP Tunneling
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Introduction
This setup will bridge DD-WRT routers, allowing any host connected to the network to be visible from the WAN cloud. To turn this HOWTO simple I'll use only two DD-WRT routers but theoretically you can further extend the setup to any number of routers.
Notes
- If your ISP do not provide you a fixed IP address, you should no create a dynamic DNS account from any DD-WRT supported provider. I'll use No-IP.com account in the examples.
- I assume you've got your WAN already up, if you need a different setup please feel free to change whatever you need.
Configuration
Generic information
- dd-wrt-01
- Address: 192.168.1.1
- Netmask: 255.255.255.0
- Gateway: 0.0.0.0
- DHCP Range: 192.168.1.100-150
- DDNS: foo-corp-dd-wrt-01.no-ip.com
- dd-wrt-02
- Address: 192.168.2.1
- Netmask: 255.255.255.0
- Gateway: 0.0.0.0
- DHCP Range: 192.168.2.100-150
- DDNS: foo-corp-dd-wrt-02.no-ip.com
dd-wrt-01
This step will configure the basic information for the local network.
- Goto Setup > Basic Setup
- Set Router Name and Host Name to "dd-wrt-01"
- Set Local IP Address to "192.168.1.1"
- Set Subnet Mask to "255.255.255.0"
- Save
Now lets make your dynamic IP address always reachable trough a hostname.
- Goto Administration > DDNS
- Set DNS Service to "No-IP.com"
- Change Username, Password and Hostname to your personal account information
- Hostname in this example will be set to "foo-corp-dd-wrt-01.no-ip.com"
- Save
Now we tell the router that there is another network on the other side of the WAN.
Basically we're telling "If you want to access any host on the 192.168.2.x subnet please forward your packet trough the router at the IP address "192.168.2.1".
- Goto Administration > Advanced Routing
- Set Route Name to "foo-corp-dd-wrt-02"
- Set Metric to "0"
- Set Destination LAN NET to "192.168.2.0"
- Set Subnet Mask to "255.255.255.0"
- Set Gateway to "192.168.2.1"
- Set Interface to "ANY"
- Save
Once uppon a time someone told that "Loopback" should be disabled, can't find a reason for it.. so I think this should be the way to go.
- Goto Administration > Management
- Enable "Loopback"
- Enable "Routing"
- Set Maximum Ports: 4096
- Set TCP Timeout: 3600
- Set UDP Timeout: 120
- Save
This router will have the role of "concentrator" meaning that every router that wants to be part of our bridge should connect to it.
If you've got a more complex design with three routers (A, B and C) traffic from B to C will always pass trough router A.
- Goto Services > VPN
- Enable PPTP Server
- Enable Broadcast Support
- Set Server IP to "192.168.1.1"
- Set Client IP(s) to "192.168.1.200-201"
- Set CHAP-Secrets to: "<PPTP_CLIENT_USERNAME_SITE02> * <PPTP_CLIENT_PASSWORD_SITE02> *"
- Disable Radius
- Disable PPTP Client Options
- Save
Saving ourselves from a headache.. ;-)
- Goto Security > VPN Passthrough
- Enable PPTP Passthrough
- Disable IPSec and L2TP Passthrough
- Save
This step maybe optional.. but routing packets trough a WAN interface without being encrypted is stupid.
- Goto Administration > Commands
- Enter "sed -i -e 's/mppe .*/mppe required,stateless/' /tmp/pptpd/options.pptpd"
- Save Startup
- NOTE: This will force all PPTP clients to use encryption
- Save
Wrapping everything up..
- Goto Administration
- Reboot Router
dd-wrt-02
- Goto Setup > Basic Setup
- Set Router Name and Host Name to "dd-wrt-02"
- Set Local IP Address to "192.168.2.1"
- Set Subnet Mask to "255.255.255.0"
- Save
- Goto Administration > DDNS
- Set DNS Service to "No-IP.com"
- Change Username, Password and Hostname to your personal account information
- Hostname in this example will be set to "foo-corp-dd-wrt-02.no-ip.com"
- Save
Now we tell the router that there is another network on the other side of the WAN.
Basically we're telling "If you want to access any host on the 192.168.1.x subnet please forward your packet trough the router at the IP address "192.168.1.1".
- Goto Administration > Advanced Routing
- Set Route Name to "foo-corp-dd-wrt-01"
- Set Metric to "0"
- Set Destination LAN NET to "192.168.1.0"
- Set Subnet Mask to "255.255.255.0"
- Set Gateway to "192.168.1.1"
- Set Interface to "ANY"
- Save
- Goto Administration > Management
- Enable "Loopback"
- Enable "Routing"
- Set Maximum Ports: 4096
- Set TCP Timeout: 3600
- Set UDP Timeout: 120
- Save
This router will have the role of "node".
- Goto Services > VPN
- Disable PPTP Server
- Enable PPTP Client Options
- Set Server IP or DNS Name to "foo-corp-dd-wrt-01.no-ip.com"
- 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"
- Enable NAT
- Set Username to "PPTP_CLIENT_USERNAME_SITE02"
- Set Password to "PPTP_CLIENT_PASSWORD_SITE02"
- Save
- Goto Security > VPN Passthrough
- Enable PPTP Passthrough
- Disable IPSec and L2TP Passthrough
- Save
Wrapping everything up..
- Goto Administration
- Reboot Router
Notes
- The router's subnets should not intersect each other (i.e. 192.168.<XXX>.1).
- The IP address pool for VPN clients must be outside the range of DHCP clients.
- In the example the IP range used for VPN clients were "192.168.1.200-201" thus 2 VPN clients are allowed to connect to our concentrator. You should increase this if more routers will be bridged.
See Also
PPTP_Server_Configuration
HOW_TO_configure_a_WINDOWS_BOX_to_make_a_VPN_Connection_to_linksys