Digging into VPN. How ISP determines that it's Remote access VPN traffic?

Posted on 2015-02-14
Last Modified: 2015-02-14
How ISP determines that it's Remote Access VPN traffic?
What about network protocols which are used for VPN?
What about roles of switches on VPN.
Question by:Nusrat Nuriyev
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Assisted Solution

by:John Hurst
John Hurst earned 500 total points
ID: 40609786
Simply, VPN passes TCP/IP packets that are encrypted. So the same rules apply at each end with regard to packets. The encryption is only in the tunnel.

Switches pass traffic at each end in a normal fashion.

I am not sure what an ISP knows about VPN. Generally VPN is independent of ISP, except that ISP's (and Hotels and like) can determine that VPN is being used (not see what is inside) and upcharge for it.

The VPN packets have header bytes that will say it is VPN and some of the characteristics of the overall packet.

Author Comment

by:Nusrat Nuriyev
ID: 40609987
Wait, you mean switch or routers?
Or the VPN scheme virtually may be like this?
office_1 <switch/router> ISP_1 <-> internet <-> ISP_2 <switch/router> office_2
Could you please explain what does mean tunnel?
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Assisted Solution

by:John Hurst
John Hurst earned 500 total points
ID: 40609988
VPN forms an encrypted tunnel inside the middle internet portion . That is done to secure the data. The encapsulation is called a tunnel.
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Author Comment

by:Nusrat Nuriyev
ID: 40609996
So, up to ISP, it goes unencrypted? But how the ISP network equipment determine that it must be encrypted after it?

Does VPN technology form new packet and put the original TCP packet inside of the payload of new packet with new header?  Does VPN make an envelope with encrypted content on top of TCP packet?

Could we say that VPN is an just ecnrypts connection  and affects to all protocols on computers on both sides, comparing with HTTPS which secures only HTTP?
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Accepted Solution

John Hurst earned 500 total points
ID: 40610035
how the ISP network equipment determine that it must be encrypted after it?

The ISP has nothing to do with the encryption, encapsulation, or tunnel. That is up to the VPN (Virtual Private Network) hardware or software on each end.

Does VPN technology form new packet and put the original TCP packet inside <-- More or less, yes. and that is what isolates from the ISP.

VPN is not HTTPS at all. Apples and oranges.

The VPN encrypts at one end and unencrypts at the other end. The overall traffic is just TCP/IP.
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Expert Comment

by:John Hurst
ID: 40610064
@Nusrat Nuriyev  - Thank you and I was happy to help. VPN (in the detail) is complicated. Good luck with your learning about it.

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