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DrayTek Vigor 2830 VPN domain authentication

Posted on 2011-10-14
Medium Priority
Last Modified: 2013-12-02
Router: DrayTek Vigor 2830
Server: Windows SBS 2011
How and is it possible to configure the DrayTek Vigor 2830 VPN for domain authentication or for the client to immediately prompt my domain credentials?
I’m quite a novice when it comes to VPNs however I have configured the VPN on the DrayTek and it connects perfectly fine... but when I connect via VPN from home and navigate to a server IP from Windows Explorer it prompts for my username and password.  
Is there any way to avoid this and add an account within the configuration of the router? Or alternatively I would like for when I connect to be prompted for my domain username and password.
Your advice would be much appreciated.
Thank you
Question by:the_omnific
  • 4
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Author Comment

ID: 36972460
I can connect via PPTP. But when I navigate to a server IP from Windows Explorer it prompts for my username and password.
I suspect that I should be using L2TP over IPSec ? How do i configure it?
LVL 18

Assisted Solution

by:Andrej Pirman
Andrej Pirman earned 2000 total points
ID: 36972507
For the proper setup you should disable VPN PPTP service on Vigor 2830, then setup VPN PPTP pass-thru in Vigor, and let Windows server accept tje dial-in call and authenticate.
If you go this way, I can provide you step-by step instructions.

Author Comment

ID: 36972533
That sounds great. Can you provide me with step by step instructions please?
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LVL 18

Assisted Solution

by:Andrej Pirman
Andrej Pirman earned 2000 total points
ID: 36973774
Here we go:

NAT --> Port Redirection
Click on one of free redirections, and create new redirection rule:

Mode: Single
Service Name: VPN  
Protocol: TCP
Public Port: -
Private IP: (LAN IP of your windows server)
Private Port:1723

FIREWALL --> Filter Setup --> 2. Default Data filter

Click on one of free filter numbers, and create new filter rule:

Comments: VPN pass
Index(1-15) in  Schedule Setup: (leave default blank)  
Direction: WAN -> LAN
Source IP:  Any  
Destination IP: (LAN IP of your windows server)  
Service Type --> EDIT
    Protocol: TCP  
    Source Port: 1 - 65535  
    Destination Port: 1723
    (other leave default)
Fragments: Don't Care
Filter: Pass Immiduatelly

VPN AND REMOTE ACCESS --> Remote Access Control
Enable PPTP VPN Service=DISABLE (un-check)

Then on your Windows server you must configure VPN server role.

Server Management --> Roles --> Add Role
You add "Network Policy and Access Services"

Under this service you enable:
- Routing and remote Access service
- Remote Access Service
- Routing

When services are installed, you navigate onto "Routing And Remote Access Service" role, right-click on it, and select PROPERTIES:
Lan IPv4 router --> LAn and demand-dial routing

Authentication provider: Windows Auth
Methods: MS-CHAPv2
Accounting provider: Windows Accounting

Enable IPv4 Forwarding= ENABLE
DHCP= Enable
Broadcast name resolution=ENABLE

All boxes checked

Also check your WINDOWS FIREWALL, if wizard enabled VPN port 1723 to be opened in direction "INBOUND" on this server. If not, create new rule and let port 1723 pass in.

Author Comment

ID: 36974308
Sorry but this method is bypassing the VPN function on the DrayTek completely. I know how to do this. I would prefer to use the DrayTek -it would be a bit of a learn curve for me as well. I just need to create some authentication for the domain on the DrayTek device somehow? Is it possible?
LVL 18

Accepted Solution

Andrej Pirman earned 2000 total points
ID: 36975717
Aha...ok, no problemo.
You are lucky having LDAP authentication built-in firmware.

So, first I suggest you check router's firmware and if it is lower than upgrade to latest FW.

Then you create new user, but do not chose default authentication, but rather auth against LDAP server. You have it on page 161 and further in user's manual http://www.draytek.com/user/PdInfoDetail.php?Id=126#PdQuLinkInfo
This user will then be able to dial-in via VPN, being it authenticated by LDAP server....but since I did not test this feature, I am not 100% how it will behave agains server resources. It is not VPN dial-in the only mechanism involved - it is caller's PC and his/her login on client PC more related to server resources, rather than VPN dial-in user.
So if you are logged-in your client PC with domain credentials, any VPN connection to domain LAN network should pass you thru.
The only prerequisite is to set on VPN connection to pass-thru NET-BIOS traffic (you set ti on Vigor VPN user's properties)
LVL 18

Assisted Solution

by:Andrej Pirman
Andrej Pirman earned 2000 total points
ID: 36975722
One other thing I forgot - SUBNETS.

If your Office LAN subnet and VPN client's home LAN are both on the same subnet, then it means trouble.
For example, both are in subnet.

VPN router tries to create ROUTE for remote VPN user's LAN subnet to Server's LAN subnet. If subnets are different, route can be created in Vigor's routing table.
But if subnets are the same, route cannot be created, because it already exists. Meaning, server cannot distinguish between LOCAL client and VPN client, and does not know, that user, for example is on local LAN, and is NOT on local LAN, but must route through Vigor.

So, easiest way to prevent this to happen is to use some non-common IP subnet on SERVER-side, for example or, which is very unlikely any other dial-in user would have setup at home.

Author Closing Comment

ID: 37030170
Thanks for your advise

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