A packet-filtering firewall uses session layer information to track the state of a connection, while a stateful firewall uses application layer information to track the state of a connection.
Both stateful and packet-filtering firewalls can filter at the application layer.
A packet-filtering firewall typically can filter up to the transport layer, while a stateful firewall can filter up to the session layer.
A stateful firewall can filter application layer information, while a packet-filtering firewall cannot filter beyond the network layer.
A packet-filtering firewall expands the number of IP addresses available and hides network addressing design.
A transparent firewall is typically implemented on a PC or server with firewall software running on it.
An application gateway firewall (proxy firewall) is typically implemented on a router to filter Layer 3 and Layer 4 information.
A stateful firewall monitors the state of connections, whether the connection is in an initiation, data transfer, or termination state.
TCP control header and trailer information associated with a particular session
source and destination IP addresses, and port numbers and sequencing information associated with a particular session
outbound and inbound access rules (ACL entries)
inside private IP address and the translated inside global IP address
TCP SYN packets and the associated return ACK packets
SYN and ACK flags
if using the established keyword, a location close to the destination to ensure that return traffic is allowed
a location as close to the source of traffic as possible
a location as close to the destination of traffic as possible
a location centered between traffic destinations and sources to filter as much traffic as possible
A dynamic ACL entry is added to the external interface in the inbound direction.
The internal interface ACL is reconfigured to allow the host IP address access to the Internet.
The entry remains in the state table after the session is terminated so that it can be reused by the host.
When traffic returns from its destination, it is reinspected, and a new entry is added to the state table.
It encrypts the entire body of the packet for more secure communications
it utilizes UDP to provide more efficient packet transfer
It combines authentication and authorization as one process
It hides passwords during transmission using PAP and sends the rest of the packet in plaintext
Denial of Service
setup privileged EXEC command and the SDM Security Audit wizard
auto secure privileged EXEC command and the SDM One-Step Lockdown wizard
aaa configuration commands and the SDM Basic Firewall wizard
class-maps, policy-maps, and service-policy configuration commands and the SDM IPS wizard
remote access security
operating system security
associate the view with the root view
assign a secret password to the view
create a view using the parser view view-name command
assign commands to the view
assign users who can use the view
create a superview using the parser view view-name command
privilege exec level 2
privilege exec level 1
privilege exec level 0
privilege exec level 15
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