McAfee HISCDE-AB-IA Product Guide - Page 61

How stateful packet inspection works, for the information. When

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Configuring Firewall Policies Overview of Firewall policies The filtering process includes the following: 1 The firewall compares an incoming packet against entries in the state table. If the packet matches any entry in the table, the packet is immediately allowed. If not, the configurable firewall rules list is examined. NOTE: A state table entry is considered a match if the Protocol, Local Address, Local Port, Remote Address and Remote Port match those of the packet. 2 If the packet matches an allow rule, it is allowed and an entry is created in the state table. 3 If the packet matches a block rule, it is blocked. 4 If the packet does not match any configurable rule, it is blocked. Figure 3: Stateful filtering process How stateful packet inspection works Stateful packet inspection combines stateful filtering with access to application-level commands, which secures protocols such as FTP. FTP involves two connections: control for commands and data for the information. When a client connects to an FTP server, the control channel is established, arriving on FTP destination port 21, and an entry is made in the state table. If the option for FTP inspection has been set with the Firewall Options policy, when the firewall encounters a connection opened on port 21, it knows to perform stateful packet inspection on the packets coming through the FTP control channel. McAfee Host Intrusion Prevention 8.0 Product Guide for ePolicy Orchestrator 4.5 61

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The filtering process includes the following:
1
The firewall compares an incoming packet against entries in the state table. If the packet
matches any entry in the table, the packet is immediately allowed. If not, the configurable
firewall rules list is examined.
NOTE:
A state table entry is considered a match if the Protocol, Local Address, Local Port,
Remote Address and Remote Port match those of the packet.
2
If the packet matches an allow rule, it is allowed and an entry is created in the state table.
3
If the packet matches a block rule, it is blocked.
4
If the packet does not match any configurable rule, it is blocked.
Figure 3: Stateful filtering process
How stateful packet inspection works
Stateful packet inspection combines stateful filtering with access to application-level commands,
which secures protocols such as FTP.
FTP involves two connections:
control
for commands and
data
for the information. When a
client connects to an FTP server, the control channel is established, arriving on FTP destination
port 21, and an entry is made in the state table. If the option for FTP inspection has been set
with the Firewall Options policy, when the firewall encounters a connection opened on port 21,
it knows to perform stateful packet inspection on the packets coming through the FTP control
channel.
Configuring Firewall Policies
Overview of Firewall policies
61
McAfee Host Intrusion Prevention 8.0 Product Guide for ePolicy Orchestrator 4.5