Asus SL6000 Setup Instructions page 101

Solwise Asus SL6000 ADSL Ethernet Router User's Guide
authentication. MD5 uses 128-bit digest and SHA1 uses 160-bit digest.
authentication while AH provides only authentication. But AH authenticates both the data and the
sender (IP header). ESP provides authentication only for the data.
Encapsulation: You could choose between a tunnel and transport encapsulations. A tunnel
encapsulation encapsulates your IP packet with another IP header before encrypting the packet. This
could be used both for traffic originating behind the Broadband gateway as well as for traffic
originating from the Broadband gateway. A transport encapsulation encrypts the packet starting from
the transport protocol headers. This could be used only for traffic originating from your Broadband
gateway.
Notes
If you are running firewall on your Broadband gateway, you need to add specific rules to the
firewall to allow the traffic to go securely over the tunnel. Add an incoming and outgoing firewall rule (in
firewall configuration) to allow the tunnel traffic to pass through firewall. Enable the 'VPN' flag in these
rules.
VPN needs a coordinated configuration at both ends of the tunnel. Ensure your configuration
matches the configuration at the remote end.
AH and ESP are security protocols. ESP provides confidentiality as well as
Chapter 7. The Configuration Pages in more detail
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