什麼是SSID BSSID ESSID

轉載自[url]http://blog.csdn.net/rzphenix/archive/2009/02/24/3933919.aspx[/url]



SSID
Short for Service Set Identifier, a 32-character unique identifier attached to the header of packets sent over a WLAN that acts as a password when a mobile device tries to connect to the BSS. The SSID differentiates one WLAN from another, so all access points and all devices attempting to connect to a specific WLAN must use the same SSID. A device will not be permitted to join the BSS unless it can provide the unique SSID. Because an SSID can be sniffed in plain text from a packet it does not supply any security to the network.

ESSID
The Extended Service Set ID (ESSID) is the name of the network you want to access. It is used to identify different wireless networks.

BSSID
The BSSID is a 48bit identity used to identify a particular BSS (Basic Service Set) within an area. In Infrastructure BSS networks, the BSSID is the MAC (Medium Access Control) address of the AP (Access Point) and in Independent BSS or ad hoc networks, the BSSID is generated randomly.

ESSID is just an extended SSID allowing for more features.



什麼是SSID/ESSID/BSSID？

SSID（Service Set Identifier）AP唯一的ID碼，用來區分不同的網絡，最多可以有32個字符，無線終端和AP的SSID必須相同方可通信。無線網卡設置了不同的SSID就可以進入不同網絡，SSID通常由AP廣播出來，通過XP自帶的掃描功能可以相看當前區域內的SSID。出於安全考慮可以不廣播SSID，此時用戶就要手工設置SSID才能進入相應的網絡。簡單說，SSID就是一個局域網的名稱，只有設置爲名稱相同SSID的值的電腦才能互相通信。

ESSID是infrastructure的應用，一個擴展的服務裝置ESS (Extended service set)由二個或多個BSS組成，形成單一的子網。使用者可於ESS上roaming及存取BSSs中的任何資料，其中Access Points必須設定相同的ESSID及channel才能允許roaming。

BSS是一種特殊的Ad-hoc LAN的應用，一個無線網絡至少由一個連接到有線網絡的AP和若干無線工作站組成，這種配置稱爲一個基本服務裝置BSS (Basic Service Set)。一羣計算機設定相同的BSS名稱，即可自成一個group，而此BSS名稱，即所謂BSSID。



通常，手機WLAN中，bssid其實就是無線路由的MAC地址. ESSID 也可認爲是SSID, WIFI 網絡名