Netgear fwag114 참조 매뉴얼
Reference Manual for the ProSafe Dual Band Wireless VPN Firewall FWAG114
Virtual Private Networking
E-5
Figure 4-8: Original packet and packet with IPSec Authentication Header
IKE Security Association
IPSec introduces the concept of the Security Association (SA). An SA is a logical connection
between two devices transferring data. An SA provides data protection for unidirectional traffic by
using the defined IPSec protocols. An IPSec tunnel typically consists of two unidirectional SAs,
which together provide a protected, full-duplex data channel.
between two devices transferring data. An SA provides data protection for unidirectional traffic by
using the defined IPSec protocols. An IPSec tunnel typically consists of two unidirectional SAs,
which together provide a protected, full-duplex data channel.
The SAs allow an enterprise to control exactly what resources may communicate securely,
according to security policy. To do this an enterprise can set up multiple SAs to enable multiple
secure VPNs, as well as define SAs within the VPN to support different departments and business
partners.
according to security policy. To do this an enterprise can set up multiple SAs to enable multiple
secure VPNs, as well as define SAs within the VPN to support different departments and business
partners.
Mode
SAs operate using modes. A mode is the method in which the IPSec protocol is applied to the
packet. IPSec can be used in tunnel mode or transport mode. Typically, the tunnel mode is used for
gateway-to-gateway IPSec tunnel protection, while transport mode is used for host-to-host IPSec
tunnel protection. A gateway is a device that monitors and manages incoming and outgoing
network traffic and routes the traffic accordingly. A host is a device that sends and receives
network traffic.
packet. IPSec can be used in tunnel mode or transport mode. Typically, the tunnel mode is used for
gateway-to-gateway IPSec tunnel protection, while transport mode is used for host-to-host IPSec
tunnel protection. A gateway is a device that monitors and manages incoming and outgoing
network traffic and routes the traffic accordingly. A host is a device that sends and receives
network traffic.
•
Transport Mode: The transport mode IPSec implementation encapsulates only the packet’s
payload. The IP header is not changed. After the packet is processed with IPSec, the new IP
packet contains the old IP header (with the source and destination IP addresses unchanged)
and the processed packet payload. Transport mode does not shield the information in the IP
header; therefore, an attacker can learn where the packet is coming from and where it is going
to. The previous packet diagrams show a packet in transport mode.
payload. The IP header is not changed. After the packet is processed with IPSec, the new IP
packet contains the old IP header (with the source and destination IP addresses unchanged)
and the processed packet payload. Transport mode does not shield the information in the IP
header; therefore, an attacker can learn where the packet is coming from and where it is going
to. The previous packet diagrams show a packet in transport mode.