This is a static archive of our old Q&A Site. Please post any new questions and answers at ask.wireshark.org.

Comunication over VPN (2 Servers)

0

Hey guys,

I have a little problem and only wanted to know if I'm right.

MachineA: 192.168.11.17 - http://www.cloudshark.org/captures/d93b8cda3ebd

Sorry for Checksum Offload here!

MachineB: 192.168.13.17 - http://www.cloudshark.org/captures/6fec5b3aa134

There's only the one stream in my trace file. What's going on there?

Regards Leo

asked 11 Jan '13, 08:06

DasLeo's gravatar image

DasLeo
1112
accept rate: 0%

What exactly is the question ?

It looks like the captures are of a connection between the two machines as seen at each machine.

(11 Jan '13, 08:26) Bill Meier ♦♦

One Answer:

1

There's only the one stream in my trace file. What's going on there?

Well, there are some differences. Some minor, some major.

Minor: Some frames with the same IP ID are different in length: #3,#5,#8. However, that's not a problem, as the difference is due to removed padding bytes in the ethernet frame.

Major: Frame #18 (MachineA) was not transmitted over the VPN tunnel, as the size was too large (4192 bytes) and the don't fragment flag was set in that segment.

If your question is: How to fix the 'major' problem?

My answer would be: Check the MTU size of the involved systems and adjust it to the requirements of your VPN, or allow IP fragmentation.

Regards
Kurt

answered 11 Jan '13, 12:05

Kurt%20Knochner's gravatar image

Kurt Knochner ♦
24.8k1039237
accept rate: 15%

Thx Kurt, that's what I needed to know!

(14 Jan '13, 23:18) DasLeo

good!

HINT: If a supplied answer resolves your question can you please "accept" it by clicking the checkmark icon next to it. This highlights good answers for the benefit of subsequent users with the same or similar questions.

(15 Jan '13, 05:17) Kurt Knochner ♦