VPN (Virtual Private Network ) , , . , , . VPN , , .
VPN Virtual Private Network, Virtual Protected Network, .. .
private : () (). , - , , , , , . , , - .
VPN - , .
VPN- . .
VPN 60- , - - Centrex (Central Exchange). , , .. , .. . IP-Centrex.
, , , . VPN IT :
Cisco L2F (Layer 2 Forwarding), L2TP (Layer 2 Tunnelling Protocol), L2TPV3 (Layer 2 Tunnelling Protocol version 3).
Microsoft PPTP (Point-To-Point Tunnelling Protocol).
Check Point Software Technologies VPN-1.
Redcreek Communications Ravlin.
Intel Landrover VPN Express.
.
VPN - . , , . , , - , , , OpenVPN. VPN - , . VPN , , -, : extranet VPN, intranet VPN, remote access VPN VPN . , , , . , . . VPN , , . , - . VPN , .
|
|
VPN
VPN -, . , . - , , peers. peer , , .
VPN , peer . , , VPN . peer . , , . 9.1.
.9.1 VPN
VPN VPN , - (encryption domain). . -, , . -, , , (.. - -). , , ( ).
, . , . VPN . , . .9.2 VPN .
|
|
.9.2
A VPN A, B VPN B, . A B, VPN A VPN . VPN B B.
, VPN , . , IP, IP . IP VPN , . - - .
VPN VPN . VPN VPN , .
, VPN :
, ,
,
, ; ,
, , / .
: L2TP, PPTP, IPSec.
IPSec
IPSec IP . , IP , .
AH (Authentication Header) - . , . , AH , .. , RFC. AH , , NAT . NAT IP , . .. , AH . , AH . .
ESP (Encapsulating Security Protocol) - , . ESP IP TCP UDP. ESP IP IP .
.. - AH ESP , ID , IP. . , TCP 6, UDP - 17. firewall , ID AH / ESP . AH ID - 51, ESP ID 50.
|
|
, IPSec - IKE Internet Key Exchange protocol. , VPN. , , IKE. , , , .
SA (Security Association) - IPSec . VPN, SA (.. AH ESP). SA , .. SA - , . SA . SA, VPN .
.. , SA , . SPI (Security Parameter Index) .
SA SAD (Security Association Database) .
IPSec - SPD Security Policy Database ( ). . VPN , .
:
/
. - (pre-shared secrets) RSA .
Diffie Hellman
PFS
AH, ESP, .
, , Diffie Hellman . . , , . , VPN . VPN , , .