VPN Access to MS Exchange Server

[Guest_imported]

I am a new user of Secure Client VPN over DSL. I am running this behind a Linksys Router. I can browse the web, and receive e-mail in Outlook 2000. If I try and send a small e-mail it works fine. If I try to send a large e-mail, I get this message: "Network Problems are Preventing the Connection to the Microsoft Exchange Server". Access to certain other applications are also not working.

I get the feeling this is an issue with the NAT on the router and the VPN. Does anyone have any ideas on how to work around this?

Thanks

 

[jbshiflett]

i am also having problems with vpn with cable modem from behind linksys router. i can always ping and telnet to internal hosts, but unable to browse or map network resource shares. i have found that problem is temporally corrected if i reboot both border router (cisco 2600) and checkpoint firebox.

anyone run into this problem with secure remote client?

 

[Guest_imported]

This is very interesting. I am having the exact same problem. As a matter of fact I was actually out surfing looking for a solution to this problem when I stumbled on this site.
I looked on Microsoft's web page and technet, I looked on Checkpoint's support site and I looked on

http://www.phoneboy.com's

site and I have not found any resolution.
I've tried Checkpoint's Sp4 for Secure Client and I tried the latest service pack for MS Office but no luck.
I will keep checking back and will post any info I find. Any help would be greatly appreciated. Thanks!

 

[Guest_imported]

I had the same problems, I use a DSL line and Checkpoint SecuRemote VPN. My DSL Driver is RASPPOE

http://user.cs.tu-berlin.de/~normanb/

You have to set the default Maximum Transfer Unit (MTU) down to at least 1460 instead of 1492 on the protocol properties (I use W2K as OS)

It solved the problem for me.

 

[Guest_imported]

It definetly look like a NAT encryption problem.

Try it without the linksys NAT device, if that work, well you got your answer...

If it doesn't, it can also be an exchange problem. Exchange returns connection port to the client after the initial connections. There's a way to fix this and select 2 specific ports of the DB and the PO.

Check on M$ for setting up exchange behind a firewall, I've seen it before.

The other way is to open fully your VPN so that all ports are accepted on it !

 

[jbshiflett]

progress is being made in figuring this vpn mess out.

problem is a the size of MTU. win2k servers ignore large mtu sizes, causing the packets to fragment and discarded by checkpoint.

registry entry on win2k server running checkpoint. add registery key of MTU on each physical interface. set value to be 1596 to allow for the overhead added by vpn encryption. reboot server and see what happens. this fix worked for me.