Firewall Network Security System PDF

1. What is the Windows Firewall and what is its purpose. Which
is better in a firewall, default permit or default deny? Why?
A firewall is a network security system, either hardware- or software-based,
that controls incoming and outgoing network traffic based on a set of rules.
Acting as a barrier between a trusted network and other untrusted networks
-- Such as the Internet
-- Or less-trusted networks
-- Such as a retail merchant's network outside of a cardholder data
environment
A firewall controls access to the resources of a network through a positive
control model. This means that the only traffic allowed onto the network
defined in the firewall policy is; all other traffic is denied.
The primary purpose of a firewall is packet filtering. When a computer sends
a request across the Internet, it takes the form of small packets of data,
which travel through the network to their destination. The target server
responds with its own packets of data, which return along the same route. A
firewall monitors every packet that passes through it, considering its source,
destination and what type of data it contains, and it compares that
information to its internal rule set. If the firewall detects that the packet is
unauthorized, it discards the data. Typically, firewalls allow traffic from
common programs such email or Web browsers, while discarding most
incoming requests. You can also configure a firewall to disallow access to
certain websites or services to prevent employees from accessing non-work
resources while on the clock.
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2. In the context of Linux what is
reiser? What does it mean when
reiser is
described as “journaled” and why might this be important to a system
administrator?
Reiser File System (ReiserFS or Reiser3 and Reiser4)
The Reiser File System (Reiser3) was created by Namesys in 2001 and added
to the Linux Kernel in version 2.4.1. Reiser3 was the first Journaling file
system included in the Linux Kernel.
Reiser4 was introduced in 2004 which was an improved Reiser3 file system.
Reiser3 Reiser4
File Size 1 EB (8TB on 32-bit system) 8TB
Max File Name Length 4032 bytes 3976 bytes
Max Volume Size 16 TB
REISER3
Reiser3 supports metadata, or block, journaling. If a crash occurs, the
Journal can be used to ‘redo’ the transactions. When the file system is
mounted and a previous crash is detected, the recovery of the items in the
Journal is automatic.
When disk space is running low on a Resier3 volume, it is possible to
perform an Online Resizing to increase the free space. Extra space is created
by using unused partitions on other hard disks. The space is added to the
existing file system increasing its size. To reduce size, which is accomplished
by removing a hard disk from the set, the shrinkage must be done while the
file system is offline.
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