Siemens SINAUT MD741-1 System Manual page 127

Network A
Computer
IP address
Network mask 255.255.255.0
Network B
Computer
IP address
Network mask 255.255.255.0
Network C
Computer
IP address
Network mask 255.255.255.0
Asymmetrical
encryption
CIDR
SINAUT MD741-1
C79000- G8976-C212
A1 A2
192.168.11.3 192.168.11.4
255.255.255.0
B1 B2
192.168.15.3 192.168.15.4
255.255.255.0
C1 C2
192.168.27.3 192.168.27.4
255.255.255.0
In asymmetrical encryption, data are encrypted with one key and
decrypted with a second key. Both keys are suitable for encryption and
decryption. One of the keys is kept secret by its owner (Private Key),
the other is issued to the public (Public Key), i.e. possible
communication partners.
A message encrypted with a Public Key can only be decrypted and
read by the recipient who has the corresponding Private Key. A
message encrypted with the Private Key can be decrypted by any
recipient who has the corresponding Public Key. Encryption with the
Private Key shows that the message actually originates from the owner
of the corresponding Public Key. We therefore speak of a digital
signature.
Asymmetrical encryption methods such as RSA are, however, slow
and vulnerable to certain attacks, which is why they are often
combined with a symmetrical method (
the other hand, concepts are also possible which avoid the complex
administration of symmetrical keys.
Classless Inter-Domain Routing
IP netmasks and CIDR are notations for grouping a number of IP
addresses into an address space. Thus a range of contiguous
addresses is treated as a network.
The CIDR method reduces, for example the routing tables stored in
routers by means of a postfix in the IP address. This postfix can be
used to designate a network together with its subnetworks. This
method is described in RFC 1518.
In order to specify a range of IP addresses to the SINAUT MD741-1, or
when configuring the firewall, it may be necessary to specify the
address space in the CIDR notation. The following table shows the IP
netmask on the left-hand side, and to the far right the corresponding
CIDR notation.
A3 A4
192.168.11.5 192.168.11.6 192.168.11.7
255.255.255.0 255.255.255.0
B3 B4
192.168.15.5 192.168.15.6
255.255.255.0 255.255.255.0
C3 C4
192.168.27.5 192.168.27.6
255.255.255.0 255.255.255.0
symmetrical encryption). On
Glossary
A5
255.255.255.0
Additional
internal
routes:
Network:
192.168.15.0/24
Gateway:
192.168.11.2
Network:
192.168.27.0/24
Gateway:
192.168.11.2
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