Share Browsing

[thnurg]

Hi,
Sorry if this has been covered already.
I have Wingate VPN on two machines. Both are behind ADSL routers which have had the necessary port opened and forwarded (809).
Machine 1 has public IP address of xxx.xxx.xxx.xxx and private address of 172.16.1.33 and is the VPN host.
Machine 2 has public IP address of yyy.yyy.yyy.yyy and private address of 192.168.0.4.
Machine 2 manages to connect into the VPN on machine 1.
Once connected I can see under published routes on the host:-
Behind NAT/translated
172.16.1.33/255.255.255.255
172.160.201.111/255.255.255.255

and I can see on the client:-
Behind NAT/translated
192.168.0.4/255.255.255.255

What I cannot see is the network share on machine 1 over the VPN.
Any pointers will be greatly appreciated.

Phil.

[jono659]

When you say you can't see the share do you mean you cant see the machine or the folder or you are unable to browse the shared folders.

JonO

[Pascal]

There are two possible scenarios here. First thing to check would be that you forwarded port 809 for TCP and UDP from the NAT/router device. If it was not done for UDP, the data channel (And network traffic) will not be seen by the VPN.

The second scenario could be MTU related. This is a direct quote from a rather detailed email that Adrien posted:

On some types of connection, there is a reduction in the MTU (Maximum Transmission Unit, which is a measure of the largest packet payload that may be sent over a network interface or point to point link). For instance PPPoE connections reduce the MTU by 8 bytes. The standard MTU for Ethernet is 1500 bytes, which means you can have up to 1500 bytes of payload over Ethernet. The Ethernet frame itself has a 14-byte header, so the actual maximum packet size (as opposed to the MTU) is 1514. WinGate VPN reduces the MTU as well, since the encryption and tunnelling require approx 50 - 60 bytes per packet.

If there are MTU issues, you can find that large (maximum size) packets can be lost. This produces strange effects such as:

Being able to connect to a network share, prompted for a password, etc. but not being able to browse large directories or transfer files.
Network drive mappings being disconnected and being unreliable.

Using Ping, you can send packets of different sizes. WinGate VPN fragments packets (if allowed) when it transfers them across the VPN. Therefore you should be able to send large ping packets successfully across the VPN if everything is working properly. If not, then once you get to a certain size, they will stop working.

To send a packet of a certain size, use the -l switch on the ping command. e.g.

ping 192.168.1.1 -l 1422

This will send a ping packet with a 1422 byte ICMP payload. It is important to note that the actual packet size of the ping packet is 28 bytes larger than this since the IP plus ICMP headers use 26 bytes. Therefore the example above will send a packet of 1450 bytes (not including the ethernet header). The ethernet header is not counted because this is stripped off and not transmitted over the VPN.

By working out the ping size that works vs the size that doesn't you can calculate what the effective MTU really is. For dialup connections and some network interfaces, it is then possible to modify the MTU so that your client machines will no longer send packets that are too big.

The last post in this topic also has some useful information on MTU settings.

http://forums.qbik.com/viewtopic.php?t= ... hlight=mtu

[thnurg]

UDP. I bet that's it. I'll post here with the results.
Thanks for your help Pascal.