78
C
4: M
HAPTER
ANAGING
D
S
EVICE
ECURITY
Select from List — Selects a protocol from a list by which packets
■
are matched to the rule.
Protocol ID — Adds user-defined protocols by which packets are
■
matched to the rule. Each protocol has a specific protocol number
which is unique. The possible field range is 0-255.
Source Port — Enables creating an ACL based on a specific protocol.
■
Any — Enables creating an ACL based on any protocol.
■
Destination Port — Defines the destination port that is matched to
■
packets. Enabled only when TCP or UDP are selected in the Protocol
list.
Any — Enables creating an ACL Based on any protocol.
■
TCP Flags — If checked, enables configuration of TCP flags matched
■
to the packet. The possible fields are:
Urg — Urgent pointer field significant. The urgent pointer points to
■
the sequence number of the octet following the urgent data.
Ack — Acknowledgement field significant. The acknowledgement
■
field is the byte number of the next byte that the sender expects to
receive from the receiver.
Psh — Push (send) the data as soon as possible, without buffering.
■
This is used for interactive traffic.
Rst — Reset the connection. This invalidates the sequence numbers
■
and aborts the session between the sender and receiver.
Syn — Synchronize Initial Sequence Numbers (ISNs). This is used to
■
initialize a new connection.
Fin — Finish. This indicates there is no more data from the sender.
■
This marks a normal closing of the session between the sender and
receiver.
For each TCP flag, the possible field values are:
Set — Enables the TCP flag.
■
Unset — Disables the TCP flag.
■
Don't Care — Does not check the packet's TCP flag.
■