User manual
Appendix A – Terminology 
278
IPSec with 
Dynamic DNS 
Dynamic DNS can be run on the IPSec endpoints thereby creating an 
IPSec tunnel using dynamic IP addresses. 
IKE  IKE is a profile of ISAKMP that is for use by IPsec. It is often called 
simply IKE. IKE creates a private, authenticated key management 
channel. Using that channel, two peers can communicate, arranging 
for sessions keys to be generated for AH, ESP or IPcomp. The 
channel is used for the peers to agree on the encryption, authentication 
and compression algorithms to be used. The traffic to which the 
policies are applied is also agreed upon. 
ISAKMP  ISAKMP is a framework for doing Security Association Key 
Management. It can, in theory, be used to produce session keys for 
many different systems, not just IPsec. 
Key lifetimes  The length of time before keys are renegotiated. 
LAN  Local Area Network. 
LED  Light-Emitting Diode. 
Local Private Key 
Certificate & 
Passphrase 
The private part of the public/private key pair of the certificate resides 
on the SG unit. The passphrase is a key that can be used to lock and 
unlock the information in the private key certificate. 
Local Public Key 
Certificate 
The public part of the public/private key pair of the certificate resides on 
the SG unit and is used to authenticate against the CA certificate. 
MAC address  The hardware address of an Ethernet interface. It is a 48-bit number 
usually written as a series of 6 hexadecimal octets, e.g. 
00:d0:cf:00:5b:da. A SG unit has a MAC address for each Ethernet 
interface. These are listed on a label on the underneath of the device. 
Main Mode  This Phase 1 keying mode automatically exchanges encryption and 
authentication keys and protects the identities of the parties attempting 
to establish the tunnel. 
Manual Keying  This type of keying requires the encryption and authentication keys to 
be specified. 
Manual Keys  Predetermined encryption and authentication keys used to establish the 
tunnel. 
Masquerade  The process when a gateway on a local network modifies outgoing 
packets by replacing the source address of the packets with its own IP 
address. All IP traffic originating from the local network appears to 
come from the gateway itself and not the machines on the local 
network. 
MD5  Message Digest Algorithm Five is a 128 bit hash. It is one of two 
message digest algorithms available in IPSec. 
NAT  Network Address Translation. The translation of an IP address used on 
one network to an IP address on another network. Masquerading is 
one particular form of NAT. 
Net mask  The way that computers know which part of a TCP/IP address refers to 
the network, and which part refers to the host range. 










