Means that whatever had been whole now exists in
parts—unattached and isolated from each other.
Network
traffic is typically fragmented into smaller pieces to fit into the physical
constraints of the underlying network architecture. Though a completely normal
behavior found in a network, fragmentation can be exploited by crackers. Because simpler firewalls and
Intrusion Detection Systems (IDS) look at only one packet of data at a time to decide
whether to block data and alert system administrators or to let the packet
pass, certain firewall and IDS rules do not “trigger” when data is
split over several packets; thus, potentially dangerous traffic can get through
the barriers.
More modern versions of these protective systems reassemble
the data before the rule set is applied. Accepting this fact, an additional
problem arises from the reassembly of packets in the security devices; namely,
different operating systems use different reassembly strategies. Crackers can
exploit the knowledge about these differing algorithms
by crafting packets so that the protective devices reassemble in such a way as
to make the system vulnerable to attack.
In the computer operating
system software domain, there are two types of fragmentation: file
fragmentation and free-space fragmentation. The former refers to computer disk
files broken into scattered parts, whereas the latter indicates that the diskÂ’s
empty space is in scattered parts instead of existing as a whole in one large,
empty space. File fragmentation causes difficulty in usersÂ’ ability to access
data stored on computer disk files, whereas free-space fragmentation causes
difficulty in usersÂ’ ability to create new data files or add to existing ones.
Actually, fragmentation interferes with any usersÂ’ computing tasks because it
slows down the computer.Â
See Also:
Algorithm; Crackers; Firewall; Intrusion Detection System (IDS); Network;
Operating System Software; Packet.
Executive.com. Introduction: Fragmentation. [Online, 2004.] Executive.com
Website. http://www.executive.com/fragbook/intro.htm#frag_def.