SSID
The account set identifier (SSID) is an alphanumeric amount set in admission credibility and radio cards to
distinguish one wireless LAN from another. For example, the absence SSID for Cisco admission points
is “tsunami.” The SSID provides a name for the wireless LAN. The alarm anatomy includes the
SSID. Microsoft Windows extracts the SSID from the radio card, which obtains SSIDs from the
beacon frames. Windows displays a account of attainable wireless networks (by SSID) to the user. If the
user chooses to affix to one of the wireless LANs, Windows initiates the affiliation process.
When installing a wireless LAN with assorted admission points, such as in the case of an enterprise
network, set all admission credibility to the aforementioned SSID. This minimizes issues with users accepting incorrect
SSIDs and ensures that adrift amid admission credibility works as calmly as attainable and without
user intervention.
Some admission points, such as the Cisco 1200, acquiesce administrators to set the admission point to disable
SSID broadcasting. Back SSID broadcasting is disabled, the admission point does not accommodate the
SSID in alarm frames. As a result, Windows is not able to admission the SSID and affectation it as a
candidate arrangement for association. This is benign in accumulated networks to accumulate accidental snoopers
and wardrivers from award the network. For example, a user with a Windows-based laptop would
not see the accumulated arrangement as an affiliation option.
With SSID broadcasting disabled, however, the user charge manually configure the radio agenda with
the actual SSID in adjustment to accessory with the admission point. This is adequate in accumulated and
home environments, but it is not adorable with attainable wireless hotspots. In the closing case, public
hotspots can use the SSID for advertising. For example, T-Mobile uses the SSID “T-Mobile” to
inform users (through Windows) that its arrangement is attainable and to analyze its account from
competitors. Disabling SSID broadcasting in attainable networks would anticipate users from
determining whether wireless LAN advantage for a accurate account provider is available.
Disabling SSID broadcasting is not a able aegis mechanism. A hacker, for example, can easily
monitor 802.11 frames on the wireless LAN and delay until an affiliation anatomy is beatific by a radio
card as a binding allotment of the affiliation process. The hacker will acquisition the SSID in association
request frames and some delving requests. In fact, bartering wireless LAN analyzers attending inside
association frames and automatically affectation SSIDs already they are found.
The 802.11 accepted specifies the charge for anniversary admission point to accept an SSID, but several vendors,
including Cisco, acquiesce assorted SSID assignments for anniversary admission point. Administrators can map
NOTE Accumulate in apperception that not all radio cards abutment the affection that Microsoft Windows
offers. Back application adaptable accessory operating systems or radio cards that do not abstract the SSID
from beacons, again the user charge manually configure the radio agenda with the SSID of the access
points that they ambition to accessory with.
Wireless Configuration Parameters 803
each SSID to a altered basic LAN (VLAN), which makes it attainable to abutment diverse
applications on a accepted wireless LAN infrastructure. This creates assorted basic wireless
LANs operating over the aforementioned concrete layer.
For example, an airport ability appetite to allotment the aforementioned wireless LAN basement to abutment both
airport check-in applications and wireless account providers alms attainable Internet admission to
passengers. The airport can attenuate SSID broadcasting for the clandestine applications and map this
SSID to a VLAN that is attainable alone through able aegis mechanisms. As a result,
passengers would not see the airport’s SSID through Windows. Anniversary admission point can be set to
broadcast the SSIDs of the attainable account providers so that users can acquisition the account offerings.
Each SSID would interface to a VLAN that connects alone with the applicative account provider.
The aboriginal radio agenda in the breadth that is set to ad hoc approach includes its SSID in the beacon. This
establishes an ad hoc wireless LAN that added users (set to ad hoc mode) can join. As with an
infrastructure network, anniversary radio agenda charge be set to the aforementioned SSID to accessory in an ad hoc
network. As with basement wireless LANs, Windows displays a account of SSIDs corresponding
to ad hoc networks. With some radio cards and back application non-Windows operating systems, it
might be all-important for anniversary ad hoc user to manually configure their radio agenda with the desired
SSID. SSID disabling is about not attainable to ad hoc users.