EH-Net

Hi all, need advise please, i need to setup vpn connection from my office as a server
to client, clients need to access accounting app(Windows 2000 server).
The problem is i have setup pptp server in my router(i used mikrotik) and the problem begin when 2 users connect at same time and use the application together
(Accounting application use foxpro and the database SQL Server 2000) show disconnect status at the program not vpn, the error is:
sometimes the error number got change, it will happen when 2 user vpn connect at the same time and they used the same ip public cause they're in same company to connect at me.
i've read this link : http://ms-news.net/f3019/error-10054-dbnetlib-connectionread-connectionwrite-3036647.html
but i'm not got any clue of what happen.
I have try to install the server of acc application to other pc using windows xp and
sql server 2008 express but not help at all, and right now i put one lan card at pc accounting application and give ip public to have accept incoming connection for users client, but when i tested to connect 2 users using the lan card i direct to internet - the error show again.

Is there any advise to this issue or the concept i used is wrong ?, i need to find out why when 2 users connect at the program via vpn at the same time will cause this error, i have asked the programmer and explain the situation and he just said there is no problem in program.

The client connect to vpn used simple connection wizard in windows xp.

And is it possible the issue come from connection client or configuration in client side ? please advise about this ?

Sorry for asking this question, i don't know how to ask this topic cause maybe
this seems like OOT, sorry  :).


Thank's a lot

If I understand you correctly, this may be a NATing issue.

There are some limitations with PPTP and certain hardware. I recall years ago that some devices only allowed 1 PPTP connection through them at a time. The PIXs used to do this. Are you 100% certain that two users can VPN into the office at the same time? Can you see these two users as active sessions on your VPN device? Have them VPN in and make sure you see them in there for at least 5 minutes. I suspect that one of the users is dropping off when the other connects. Can you ping both clients when they are both connected?

Also, can more than one user connect to your application from inside the network? If that works fine, I'd focus your attention on the VPN. You may want to try an IPSec VPN - that wont have the same limitations.

-c

I'll second the suggestion to move to IPSec. As you are using mikrotik, you can find a video on how to do just that at  greg sowell's site.
http://gregsowell.com/?page_id=951 (http://gregsowell.com/?page_id=951)

Sorry for reply right now,

@cd1zz, i'm very sure the users can connect to vpn at same time, but the problem is
just when accessing application program - even when application program error disconnected it just make error on program access not the vpn, thank's
@WCNA, i've try to setup ipsec but on my experience it's show the same error on the way users connected to application program.
@CadillacGolfer
yeah, in my mikrotik and client that connect to my vpn we're use nat, but if this is
NATing issue, if you don't mind could you please give me some advise to fix this issue, cause as i read in google NATing issue can make the pptp connection fail
but if it's true why it just make the connection to application program fail when users connect to my vpn but not make vpn connection lost or error access to any directory share in my network.

And, maybe my question is stupid but what kind of speed when users access vpn and go browse directory sharing at my network, is it normal if sometimes users experienced some kind of slow when access it ?

Thank's a lot and need help and advise please.

Does the application work as designed INSIDE the network? Is this problem isolated to ONLY VPN users?

@cd1zz , yes, you're right this problem only occured only vpn users, in inside network
there is no problem like this.

Do you have any idea to find out this issue ?

Thank's a lot

We can certainly try! A few more questions for you:

• Are the VPN clients getting DHCP from your Mikrotik?
• Are the VPN clients on a different subnet than your application server?
• When the clients are VPNd in, can you do an extended ping on them to see if there is any packet loss? I would do this simultaneously between the two clients.
• Are you certain this is isolated to only this application server? For example, can you see if they can get to file shares or other applications without an issue? I am just trying to isolate the issue, if everything else works, and its only your VPN clients getting to this ONE specific application, then there is probably a configuration problem on the VPN server or perhaps the application has something else we need to look at.
• Then I would fire up wireshark to look at the packet captures for both clients as they are connecting to your application. Save those to a pcap file and PM me so you can email them to me if you want me to look at them.
• What is the name of the application? You can PM me if you don't want to broadcast it to the world...

Thank's for your reply:
1. vpn client getting static ip i set from mikrotik for each client vpn
2. the client vpn when connect to vpn get the ip same as subnet as my network,
   but the real client ip subnet is different from my network(sorry for my explanation)
3. yes, this only happen when 2 client connect to application program via vpn, like
   i said on my previous post even when they disconnected from application program
   they still connect to my network via vpn and still can browse share folder network,
4. yeah, i want to do it from long time but it seems the client support just think, if
   the problem came from my configuration, well i need time about this to convince
  them to run network analyzer in client side

Sorry cd1zz, but can i know your email so i can pm you ?

Thank's a lot for your help i'm very grateful.

Run the packet captures from your application server. No need to run them on the clients.