Wireless networks الشبكات اللاسلكيه 4

‫ري‬

Wireless Networks

‫ري‬

‫تھ نا‬

1 ‫تو ا‬

‫ھ نا‬

‫ھ نا‬

‫ري‬

‫‪Wireless Networks‬‬

‫ا"‬

‫و‬

‫تا !‬

‫‪Wireless Networks‬‬

‫ا ‪ %‬ا‪$‬ول‪ :‬ا "‬

‫تا !‬

‫ﻤﺤﻁﺔ ﺍﻝﻌﻤل ﺍﻝﻼﺴﻠﮑﻴﺔ‬ ‫ا‬

‫ت‬

‫ﻁﺭﻴﻘﺔ ﺇﻋﺩﺍﺩ ﺸﺒﮑﺔ ﻻﺴﻠﮑﻴﺔ ﺒﺴﻴﻁﺔ‬ ‫ﺯﻴﺎﺩﺓ ﻗﻭﺓ ﺍﻹﺸﺎﺭﺓ ﻓﻲ ﺍﻝﺸﺒﮑﺎﺕ ﺍﻝﻼﺴﻠﮑﻴﺔ‬

‫ا ‪ %‬ا * ﻧ&‪ :‬و!( ا'ر! ل ا ‪ & %‬وا ! &‬ ‫ا ھ‬

‫ا ‪ %‬ا * ‪ :+‬ا "‬

‫‪VPN‬‬

‫ﻤﻤﻴﺯﺍﺕ ﺸﺒﮑﺔ ‪VPN‬‬ ‫ﺘﺠﻬﻴﺯ ﺨﺎﺩﻡ ‪VPN‬‬

‫ا ‪ %‬ا ا ‪ :.‬أ ‪ ,‬ا "‬

‫‪2‬‬ ‫تو ا‬

‫تا !‬

‫ھ نا‬

‫ري‬

‫‪Wireless Networks‬‬

‫ا ‪ %‬ا‪$‬ول‪ :‬ا "‬

‫تا !‬

‫ﺘﻭﻓﺭ ﺍﻷﺴﻼﻙ ﺨﻴﺎﺭﺍﺕ ﻓﻌﺎﻝﺔ ﻝﺘﺒﺎﺩل ﺍﻝﺒﻴﺎﻨﺎﺕ ﻭﺍﻝﻤﻭﺍﺭﺩ ﻋﺒﺭ ﺍﻝـﺸﺒﮑﺎﺕ‪ ،‬ﻭﻝﮑـﻥ‬ ‫ﺍﻷﺴﻼﻙ ﮑﻭﺴﻁ ﺇﺭﺴﺎل ﻻ ﻴﺨﻠﻭ ﻤﻥ ﺍﻝﻌﻴﻭﺏ‪ ،‬ﺍﻝﺘﻲ ﺃﻫﻤﻬﺎ ﻋﺩﻡ ﻤﺭﻭﻨﺘﻬﺎ‪ ،‬ﻷﻨﻬﺎ ﺇﺫﺍ ﻤﺩﺕ‬ ‫ﻭﺭﮑﺒﺕ ﻴﺼﺒﺢ ﻤﻥ ﺍﻝﺼﻌﺏ ﻨﺴﺒﻴﺎﹰ ﺇﻋﺎﺩﺓ ﺘﺭﮑﻴﺒﻬﺎ ﻓﻲ ﻤﮑﺎﻥ ﺁﺨﺭ ﺩﻭﻥ ﺒﺫل ﺠﻬﺩ ﻭﻤﻀﺎﻴﻘﺔ‬ ‫ﻻ ﻝﻠﻤﺴﺘﺨﺩﻤﻴﻥ ﮑﺜﻴﺭﻱ ﺍﻝﺘﻨﻘل‪.‬‬ ‫ﻝﻠﻤﺴﺘﺨﺩﻤﻴﻥ‪ ،‬ﮑﻤﺎ ﺃﻨﻬﺎ ﻻ ﺘﻭﻓﺭ ﺍﺘﺼﺎ ﹰ‬ ‫ﻻ ﻝﻠﺘـﺸﺒﻴﻙ ﻓـﻲ‬ ‫ﺒﺩﺃﺕ ﺍﻝﺸﺒﮑﺎﺕ ﺍﻝﻤﺤﻠﻴﺔ ﺍﻝﻼﺴﻠﮑﻴﺔ ‪ LAN Wireless‬ﺘﺸﮑل ﺨﻴﺎﺭﹰﺍ ﻓﻌﺎ ﹰ‬ ‫ﺍﻵﻭﻨﺔ ﺍﻷﺨﻴﺭﺓ‪ ،‬ﻭﺍﻝﺴﺒﺏ ﻓﻲ ﺫﻝﻙ ﻴﺘﻠﺨﺹ ﻓﻲ‪:‬‬ ‫‪ -1‬ﺍﻝﺘﻁﻭﺭﺍﺕ ﺍﻝﻤﺘﻼﺤﻘﺔ ﻓﻲ ﺍﻝﺘﻘﻨﻴﺎﺕ ﻭﺍﻝﻤﻨﺘﺠﺎﺕ ﺍﻝﻼﺴﻠﮑﻴﺔ‪.‬‬ ‫‪ -2‬ﺍﻻﻨﺨﻔﺎﺽ ﺍﻝﻤﺘﻭﺍﺼل ﻓﻲ ﺍﻷﺴﻌﺎﺭ‪ ،‬ﻨﻅﺭﹰﺍ ﻝﻠﺘﻨﺎﻓﺱ ﺍﻝﻤﺘﺯﺍﻴﺩ ﺒﻴﻥ ﺍﻝﻤﺼﻨﻌﻴﻥ‪.‬‬ ‫‪ -3‬ﺍﻝﻁﻠﺏ ﺍﻝﻤﺘﺯﺍﻴﺩ ﻋﻠﻰ ﻫﺫﻩ ﺍﻝﺸﺒﮑﺎﺕ ﺒﺴﺒﺏ ﺍﻝﺤﺭﻴﺔ ﺍﻝﮑﺒﻴﺭﺓ ﺍﻝﺘﻲ ﺘﻭﻓﺭﻫﺎ ﻝﻠﻤﺴﺘﺨﺩﻤﻴﻥ‬ ‫ﻓﻲ ﺍﻝﺘﻨﻘل ﺩﻭﻥ ﺃﻥ ﻴﺅﺜﺭ ﺫﻝﻙ ﻋﻠﻰ ﻋﻤﻠﻬﻡ‪.‬‬ ‫ﺘﺴﺘﻁﻴﻊ ﺍﻝﻤﮑﻭﻨﺎﺕ ﺍﻝﻼﺴﻠﮑﻴﺔ ﺃﺩﺍﺀ ﺍﻝﻤﻬﺎﻡ ﺍﻝﺘﺎﻝﻴﺔ‪:‬‬ ‫‪ -1‬ﺘﻭﻓﻴﺭ ﺍﺘﺼﺎﻻﺕ ﻤﺅﻗﺘﺔ ﻝﺸﺒﮑﺎﺕ ﺴﻠﮑﻴﺔ ﻓﻲ ﺤﺎل ﻓـﺸل ﻫـﺫﻩ ﺍﻷﺴـﻼﻙ ﺒﺘـﻭﻓﻴﺭ‬ ‫ﺍﻻﺘﺼﺎل ﺍﻝﻤﻁﻠﻭﺏ ﻷﻱ ﺴﺒﺏ ﮑﺎﻥ‪.‬‬ ‫‪ -2‬ﺍﻝﻤﺴﺎﻋﺩﺓ ﻓﻲ ﻋﻤل ﻨﺴﺨﺔ ﺍﺤﺘﻴﺎﻁﻴﺔ ﻤﻥ ﺍﻝﺒﻴﺎﻨﺎﺕ ﻋﻠﻰ ﺸﺒﮑﺔ ﺴﻠﮑﻴﺔ ﺇﻝـﻰ ﺠﻬـﺎﺯ‬ ‫ﻤﺘﺼل ﻻﺴﻠﮑﻴﺎﹰ‪.‬‬ ‫‪ -3‬ﺘﻭﻓﻴﺭ ﺩﺭﺠﺔ ﻤﻥ ﺍﻝﺤﺭﻴﺔ ﻓﻲ ﺍﻝﺘﻨﻘل ﻝﺒﻌﺽ ﺍﻝﻤﺴﺘﺨﺩﻤﻴﻥ ﻓﻲ ﺸﺒﮑﺔ ﺴﻠﮑﻴﺔ‪.‬‬ ‫ﺘﻌﺘﺒﺭ ﺍﻝﺸﺒﮑﺎﺕ ﺍﻝﻼﺴﻠﮑﻴﺔ ﻤﻔﻴﺩﺓ ﻓﻲ ﺍﻝﺤﺎﻻﺕ ﺍﻝﺘﺎﻝﻴﺔ‪:‬‬ ‫‪ -1‬ﺘﻭﻓﻴﺭ ﺍﺘﺼﺎﻻﺕ ﻓﻲ ﺍﻷﻤﺎﮑﻥ ﺍﻝﻤﺯﺩﺤﻤﺔ‪.‬‬ ‫‪ -2‬ﺘﻭﻓﻴﺭ ﺍﺘﺼﺎﻻﺕ ﻝﻠﻤﺴﺘﺨﺩﻤﻴﻥ ﮑﺜﻴﺭﻱ ﺍﻝﺘﻨﻘل‪.‬‬ ‫‪ -3‬ﺒﻨﺎﺀ ﺸﺒﮑﺎﺕ ﻓﻲ ﺍﻷﻤﺎﮑﻥ ﺍﻝﻤﻌﺯﻭﻝﺔ ﺍﻝﺘﻲ ﻴﺼﻌﺏ ﺘﻭﺼﻴﻠﻬﺎ ﺒﺄﺴﻼﻙ‪.‬‬

‫‪3‬‬ ‫تو ا‬

‫ھ نا‬

‫ري‬

‫‪Wireless Networks‬‬

‫ﻭﻴﻤﮑﻥ ﺘﺸﺒﻴﻪ ﺍﻝﺸﺒﮑﺎﺕ ﺍﻝﻼﺴﻠﮑﻴﺔ ﺒﺸﺒﮑﺎﺕ ﺍﻝﻬﺎﺘﻑ ﺍﻝﻤﺤﻤﻭ‪،‬ل ﻓﺎﻝﻤﺴﺘﺨﺩﻡ ﻴﺴﺘﻁﻴﻊ‬ ‫ﻼ ﺒﺸﺒﮑﺘﻪ ﻤﺎ ﺩﺍﻡ ﻴﻘﻊ ﻓﻲ ﺍﻝﻤﺩﻯ ﺍﻝﺫﻱ‬ ‫ﺍﻝﺘﻨﻘل ﺇﻝﻰ ﺃﻱ ﻤﮑﺎﻥ ﻴﺤﻠﻭ ﻝﻪ ﻭﻴﺒﻘﻰ ﻤﻊ ﺫﻝﻙ ﻤﺘﺼ ﹰ‬ ‫ﺘﻐﻁﻴﻪ ﺍﻝﺸﺒﮑﺔ‪ .‬ﻗﺩ ﻴﮑﻭﻥ ﻤﺼﻁﻠﺢ ﻻﺴﻠﮑﻲ ﻤﻀﻠل ﻨﻭﻋ ﹰﺎ ﻤﺎ ﻓﺄﻏﻠﺏ ﺍﻝـﺸﺒﮑﺎﺕ ﻻ ﺘﮑـﻭﻥ‬ ‫ﻻﺴﻠﮑﻴﺔ ﺘﻤﺎﻤﺎ‪ ،‬ﻓﻔﻲ ﺃﻏﻠﺏ ﺍﻷﺤﻴﺎﻥ ﺘﮑﻭﻥ ﻫﺫﻩ ﺍﻝﺸﺒﮑﺎﺕ ﻋﺒﺎﺭﺓ ﻋﻥ ﺨﻠﻴﻁ ﻤﻥ ﺍﻷﺠﻬـﺯﺓ‬ ‫ﺍﻝﻤﻭﺼﻠﺔ ﺒﺄﺴﻼﻙ ﻭﺃﺠﻬﺯﺓ ﺃﺨﺭﻯ ﻤﻭﺼﻠﺔ ﻻﺴﻠﮑﻴﺎ‪ ،‬ﻫﺫﺍ ﺍﻝﻨﻭﻉ ﻤﻥ ﺍﻝﺸﺒﮑﺎﺕ ﻴﻁﻠﻕ ﻋﻠﻴﻬﺎ‬ ‫ﺸﺒﮑﺎﺕ ﻫﺠﻴﻨﺔ ‪.Hybrid‬‬

‫‪4‬‬ ‫تو ا‬

‫ھ نا‬

‫ري‬

‫‪Wireless Networks‬‬

‫ﻤﺤﻁﺔ ﺍﻝﻌﻤل ﺍﻝﻼﺴﻠﮑﻴﺔ‪:‬‬ ‫ﻭﺘﻌﻤل ﺒﺸﮑل ﻤﺸﺎﺒﻪ ﻝﻠﻤﺤﻁﺎﺕ ﺍﻝﺴﻠﮑﻴﺔ ﻭﺍﻻﺨﺘﻼﻑ ﺍﻝﻭﺤﻴﺩ ﻴﺘﻤﺜﻝـ ﻓـﻲ ﻭﺴـﻁ‬ ‫ﺍﻹﺭﺴﺎل ﺍﻝﻤﺴﺘﺨﺩﻡ‪ .‬ﮑل ﺠﻬﺎﺯ ﻓﻲ ﺍﻝﺸﺒﮑﺎﺕ ﺍﻝﻼﺴﻠﮑﻴﺔ ﻴﺤﺘﻭﻱ ﻋﻠﻰ ﮑﺎﺭﺕ ﺸﺒﮑﺔ ﻻﺴﻠﮑﻴﺔ‬ ‫ﻤﻊ ﻤﺭﺴل ﻤﺴﺘﻘﺒل ‪ Transceiver‬ﻻﺴﻠﮑﻲ‪ .‬ﻭﻴﻘﻭﻡ ‪ Transceiver‬ﺒﺈﺫﺍﻋﺔ ﻭﺍﺴـﺘﻘﺒﺎل‬ ‫ﺍﻹﺸﺎﺭﺍﺕ ﻤﻥ ﻭﺇﻝﻰ ﺃﺠﻬﺯﺓ ﺍﻝﺤﺎﺴﺏ ﺍﻝﻤﺤﻴﻁﺔ ﺒﻪ‪ .‬ﺃﻤﺎ ﻓـﻲ ﺍﻝـﺸﺒﮑﺎﺕ ﺍﻝﻬﺠﻴﻨـﺔ ﻓـﺈﻥ‬ ‫‪ Transceiver‬ﻴﺴﻤﺢ ﻝﻸﺠﻬﺯﺓ ﺍﻝﻼﺴﻠﮑﻴﺔ ﺒﺎﻻﺘﺼﺎل ﻤﻊ ﺍﻷﺠﻬـﺯﺓ ﺍﻝﻤﮑﻭﻨـﺔ ﻝﻠـﺸﺒﮑﺔ‬ ‫ﺍﻝﺴﻠﮑﻴﺔ‪.‬‬ ‫ﻫﻨﺎﻙ ﺜﻼﺙ ﺘﻘﻨﻴﺎﺕ ﺃﺴﺎﺴﻴﺔ ﺘﺴﺘﺨﺩﻡ ﻓﻲ ﺇﺭﺴﺎل ﺍﻝﺒﻴﺎﻨﺎﺕ ﻓﻲ ﺍﻝﺸﺒﮑﺎﺕ ﺍﻝﻼﺴﻠﮑﻴﺔ ﺍﻝﻤﺤﻠﻴﺔ‪:‬‬ ‫• ﻤﻭﺠﺎﺕ ﺍﻝﺭﺍﺩﻴﻭ ﺃﺤﺎﺩﻴﺔ ﺍﻝﺘﺭﺩﺩ ‪ Radio Single-Frequency‬ﻭﺘﺴﻤﻰ ﺃﺤﻴﺎﻨـ ﹰﺎ‬ ‫ﻤﻭﺠﺎﺕ ﺍﻝﺭﺍﺩﻴﻭ ﻋﺎﻝﻴﺔ ﺍﻝﺘﺭﺩﺩ ﻀﻴﻘﺔ ﺍﻝﻨﻁﺎﻕ‪.‬‬ ‫‪Narrow-Band High-Frequency Radio .‬‬ ‫• ﻤﻭﺠﺎﺕ ﺭﺍﺩﻴﻭ ﺍﻝﻁﻴﻑ ﺍﻹﻨﺘﺸﺎﺭﻱ ‪Spread-Spectrum Radio.‬‬ ‫• ﻤﻭﺠﺎﺕ ﺍﻷﺸﻌﺔ ﺘﺤﺕ ﺍﻝﺤﻤﺭﺍﺀ ‪.Infrared‬‬ ‫ﻴﻌﻤل ﺍﻻﺘﺼﺎل ﺒﻤﻭﺠﺎﺕ ﺍﻝﺭﺍﺩﻴﻭ ﻓﻲ ﺸﺒﮑﺎﺕ ﺍﻝﺤﺎﺴﺏ ﺒﺸﮑل ﻤﺸﺎﺒﻪ ﻝﻤﺎ ﻫﻭ ﻋﻠﻴﻪ‬ ‫ﻓﻲ ﺸﺒﮑﺎﺕ ﺍﻹﺫﺍﻋﺔ‪ ،‬ﻓﺎﻝﺠﻬﺎﺯ ﺍﻝﻤﺭﺴل ﻴﻘﻭﻡ ﺒﺈﺭﺴﺎل ﺇﺸﺎﺭﺍﺘﻪ ﺒﺎﺴﺘﺨﺩﺍﻡ ﺘﺭﺩﺩ ﻤﻌﻴﻥ ﻭﻴﻘﻭﻡ‬ ‫ﺍﻝﺠﻬﺎﺯ ﺍﻝﻤﺴﺘﻘﺒل ﺒﻀﺒﻁ ﺘﺭﺩﺩﻩ ﻝﻴﺘﻭﺍﻓﻕ ﻤﻊ ﺘﺭﺩﺩ ﺍﻝﺠﻬﺎﺯ ﺍﻝﻤﺭﺴل ﻝﮑـﻲ ﻴـﺘﻤﮑﻥ ﻤـﻥ‬ ‫ﺍﺴﺘﻘﺒﺎل ﺍﻹﺸﺎﺭﺍﺕ‪ .‬ﺍﻻﺨﺘﻼﻑ ﺍﻝﻭﺤﻴﺩ ﺒﻴﻥ ﺸﺒﮑﺎﺕ ﺤﺎﺴﺏ ﺍﻝﺭﺍﺩﻴﻭ ﻭﺸﺒﮑﺎﺕ ﺍﻹﺫﺍﻋﺔ ﻫﻭ‬ ‫ﺃﻥ ﺍﻝﺸﺒﮑﺎﺕ ﺒﻤﻭﺠﺎﺕ ﺍﻝﺭﺍﺩﻴﻭ ﺘﻘﻭﻡ ﺒﺈﺭﺴﺎل ﺍﻝﺒﻴﺎﻨﺎﺕ ﻭﻝﻴﺱ ﺍﻝﺭﺴﺎﺌل ﺍﻝﺼﻭﺘﻴﺔ ﮑﻤﺎ ﻓـﻲ‬ ‫ﺸﺒﮑﺎﺕ ﺍﻹﺫﺍﻋﺔ‪ .‬ﻭﻴﻌﻤل ‪ Transceiver‬ﺃﺤﺎﺩﻱ ﺍﻝﺘﺭﺩﺩ ﮑﻤﺎ ﻴﻅﻬﺭ ﻤﻥ ﺍﺴﻤﻪ ﺒﺎﺴـﺘﺨﺩﺍﻡ‬ ‫ﺘﺭﺩﺩ ﻭﺍﺤﺩ ﻓﻘﻁ‪.‬‬

‫‪5‬‬ ‫تو ا‬

‫ھ نا‬

‫ري‬

‫‪Wireless Networks‬‬

‫ﺘﺴﺘﻁﻴﻊ ﺃﻨﻅﻤﺔ ﺍﻝﺭﺍﺩﻴﻭ ﺃﺤﺎﺩﻱ ﺍﻝﺘـﺭﺩﺩ ‪ Radio Single-Frequency‬ﺍﻝﻌﻤﻝـ‬ ‫ﺒﺎﺴﺘﺨﺩﺍﻡ ﺃﻱ ﺘﺭﺩﺩ ﻴﻨﺘﻤﻲ ﺇﻝﻰ ﻤﺩﻯ ﺘﺭﺩﺩﺍﺕ ﺍﻝﺭﺍﺩﻴـﻭ ‪Radio Frequency Range‬‬ ‫)‪ ،(RF‬ﻭﺒﺸﮑل ﻋﺎﻡ ﺘﺴﺘﺨﺩﻡ ﺸﺒﮑﺎﺕ ﺍﻝﺤﺎﺴﺏ ﺍﻝﻤﺩﻯ ﺍﻝﻌﺎﻝﻲ ﻤﻥ ﻁﻴﻑ ﺘﺭﺩﺩﺍﺕ ﺍﻝﺭﺍﺩﻴـﻭ‬ ‫ﻭﺍﻝﺘﻲ ﺘﻘﺎﺱ ﺒﺎﻝﻐﻴﻐﺎﻫﻴﺭﺘﺯ‪ ،‬ﻭﺫﻝﻙ ﻷﻨﻬﺎ ﺘﻭﻓﺭ ﻤﻌﺩﻻﺕ ﺇﺭﺴﺎل ﺃﻋﻠﻰ ﻝﻠﺒﻴﺎﻨﺎﺕ‪.‬‬ ‫ﻭﺒﺸﮑل ﻋﺎﻡ‪ ،‬ﻓﺈﻥ ﺃﻨﻅﻤﺔ ﺇﺭﺴﺎل ﺍﻝﺭﺍﺩﻴﻭ ﺴﻬﻠﺔ ﺍﻝﺘﺭﮑﻴﺏ ﻭﺍﻹﻋﺩﺍﺩ‪ ،‬ﻭﻝﮑﻥ ﺍﺴﺘﺨﺩﺍﻡ‬ ‫ﺃﻨﻅﻤﺔ ﻋﺎﻝﻴﺔ ﺍﻝﻁﺎﻗﺔ ﻝﺘﻐﻁﻴﺔ ﻤﺴﺎﺤﺎﺕ ﮑﺒﻴﺭﺓ ﻴﻌﺘﺒﺭ ﺃﮑﺜﺭ ﺘﻌﻘﻴﺩﹰﺍ ﻷﻨﻬﺎ ﺘـﺴﺘﺨﺩﻡ ﺃﺠﻬـﺯﺓ‬ ‫ﻋﺎﻝﻴﺔ ﺍﻝﺠﻬﺩ ﻭﺘﺤﺘﺎﺝ ﺇﻝﻰ ﺼﻴﺎﻨﺔ ﻤﺴﺘﻤﺭﺓ ﻭﺃﻴﺩﻱ ﻋﺎﻤﻠﺔ ﺨﺒﻴﺭﺓ‪ .‬ﻭﺘﺫﮑﺭ ﺃﻥ ﺍﻹﻋﺩﺍﺩ ﺍﻝﺴﻴﺊ‬ ‫ﻷﺠﻬﺯﺓ ﺍﻝﺘﺭﺩﺩ ﺍﻷﺤﺎﺩﻱ ﻗﺩ ﻴﺅﺩﻱ ﺇﻝﻰ‪:‬‬ ‫• ﺇﺸﺎﺭﺍﺕ ﻤﺯﻴﻔﺔ‪.‬‬ ‫• ﺍﺴﺘﺨﺩﺍﻡ ﻀﻌﻴﻑ ﻝﻘﻭﺓ ﺍﻹﺭﺴﺎل‪.‬‬ ‫• ﻤﻌﺩﻻﺕ ﺇﺭﺴﺎل ﺒﻴﺎﻨﺎﺕ ﻤﻨﺨﻔﻀﺔ‪.‬‬ ‫ﻴﻌﺘﻤﺩ ﺍﻝﺘﻀﻌﻴﻑ ﻓﻲ ﺇﺸﺎﺭﺍﺕ ﺍﻝﺭﺍﺩﻴﻭ ﻋﻠﻰ ﺘﺭﺩﺩ ﻭﻗﻭﺓ ﺍﻹﺸﺎﺭﺓ ﺍﻝﻤﺭﺴﻠﺔ‪ ،‬ﻓﮑﻠﻤـﺎ‬ ‫ﺍﺭﺘﻔﻊ ﺍﻝﺘﺭﺩﺩ ﻭﻗﻭﺓ ﺍﻹﺸﺎﺭﺓ ﮑﻠﻤﺎ ﺃﺼﺒﺢ ﺍﻝﺘﻀﻌﻴﻑ ﺃﻗل‪ .‬ﻭﺤﻴﺙ ﺃﻥ ﺃﺠﻬﺯﺓ ﺍﻝﺭﺍﺩﻴـﻭ ﺫﺍﺕ‬ ‫ﺍﻝﺘﺭﺩﺩ ﺍﻷﺤﺎﺩﻱ ﺭﺨﻴﺼﺔ ﺍﻝﺜﻤﻥ ﺘﻌﻤل ﺒﺎﺴﺘﺨﺩﺍﻡ ﺘﺭﺩﺩ ﻤﻨﺨﻔﺽ ﻭﻗﻭﺓ ﻤﺤﺩﻭﺩﺓ ﻓﺈﻨﻬﺎ ﻋﺎﺩﺓ‬ ‫ﺘﻌﺎﻨﻲ ﻤﻥ ﻤﻌﺩﻻﺕ ﺘﻀﻌﻴﻑ ﻋﺎﻝﻴﺔ‪ ،‬ﻭﻝﻬﺫﺍ ﻓﺈﻨﻬﺎ ﻻ ﺘﺴﺘﻁﻴﻊ ﺘﻐﻁﻴﺔ ﻤـﺴﺎﺤﺔ ﮑﺒﻴـﺭﺓ ﻭﻻ‬ ‫ﺘﺴﺘﻁﻴﻊ ﺍﻝﻤﺭﻭﺭ ﺨﻼل ﺍﻷﺠﺴﺎﻡ ﺍﻝﮑﺜﻴﻔﺔ ﻭﺍﻝﻤﺼﻤﺘﺔ‪ .‬ﻭﺒﺸﮑل ﻋﺎﻡ ﺘﻌﺘﺒﺭ ﺃﺠﻬﺯﺓ ﺍﻝﺭﺍﺩﻴـﻭ‬ ‫ﺃﺤﺎﺩﻱ ﺍﻝﺘﺭﺩﺩ ﺃﻗل ﺘﮑﻠﻔﺔ ﻤﻥ ﻏﻴﺭﻫﺎ ﻤﻥ ﺍﻝﻭﺴﺎﺌﻁ ﺍﻝﻼﺴﻠﮑﻴﺔ ﻭﺘﻌﻤﻝـ ﺒﺘـﺭﺩﺩﺍﺕ ﺃﮑﺜـﺭ‬ ‫ﺍﻨﺨﻔﺎﻀﺎ ﻭﻻ ﺘﺘﺠﺎﻭﺯ ﻗﻭﺓ ﺍﻹﺸﺎﺭﺓ ﺃﮑﺜﺭ ﻤﻥ ﻭﺍﺕ ﻭﺍﺤﺩ‪ .‬ﻭﺘﺘﺭﺍﻭﺡ ﺴﺭﻋﺔ ﻨﻘل ﺍﻝﺒﻴﺎﻨـﺎﺕ‬ ‫ﻓﻲ ﺸﺒﮑﺎﺕ ﺍﻝﺭﺍﺩﻴﻭ ﺃﺤﺎﺩﻴﺔ ﺍﻝﺘﺭﺩﺩ ﺒﻴﻥ ‪ 1‬ﻤﻴﺠﺎﺒﺕ ﻓﻲ ﺍﻝﺜﺎﻨﻴﺔ ﻭ ‪ 10‬ﻤﻴﺠﺎﺒﺕ ﻓﻲ ﺍﻝﺜﺎﻨﻴﺔ‪.‬‬ ‫ﺘﻌﺘﺒﺭ ﺇﺸﺎﺭﺍﺕ ﺍﻝﺭﺍﺩﻴﻭ ﺃﺤﺎﺩﻱ ﺍﻝﺘﺭﺩﺩ ﻋﺭﻀﺔ ﻝﻠﺘﺩﺍﺨل ﺍﻝﮑﻬﺭﻭﻤﻐﻨﺎﻁﻴﺴﻲ ﻭﺨﺎﺼﺔ ﻓـﻲ‬ ‫ﻤﺩﻯ ﺍﻝﺘﺭﺩﺩ ﺍﻝﻤﻨﺨﻔﺽ ﻭﺍﻝﺫﻱ ﻴﺘﺩﺍﺨل ﻤﻊ ﻤﻭﺠﺎﺕ ﺃﺠﻬﺯﺓ ﺍﻝﻤﺴﺘﻬﻠﮑﻴﻥ ﻤﺜل ﺃﺠﻬﺯﺓ ﻓـﺘﺢ‬ ‫ﺃﺒﻭﺍﺏ ﻤﺭﺁﺏ ﺍﻝﺴﻴﺎﺭﺍﺕ‪ .‬ﺇﻥ ﺍﻋﺘﺭﺍﺽ ﺍﻹﺸﺎﺭﺍﺕ ﻭﺍﻝﺘﺠﺴﺱ ﻋﻠﻴﻬﺎ ﻓﻲ ﻫﺫﻩ ﺍﻷﻨﻅﻤﺔ ﺃﻤﺭ‬ ‫‪6‬‬ ‫تو ا‬

‫ھ نا‬

‫ري‬

‫‪Wireless Networks‬‬

‫ﻏﺎﻴﺔ ﻓﻲ ﺍﻝﺴﻬﻭﻝﺔ ﺇﺫﺍ ﻋﺭﻑ ﺘﺭﺩﺩ ﺍﻹﺭﺴﺎل‪ .‬ﺃﻤﺎ ﺸﺒﮑﺎﺕ ﺭﺍﺩﻴﻭ ﺍﻝﻁﻴـﻑ ﺍﻹﻨﺘـﺸﺎﺭﻱ ﺃﻭ‬ ‫ﻤﺘﻌﺩﺩ ﺍﻝﺘﺭﺩﺩ ‪ Spread-Spectrum Radio‬ﻓﻬﻲ ﺘﻌﺘﺒﺭ ﺍﻝﺘﻘﻨﻴﺔ ﺍﻷﮑﺜﺭ ﺍﺴﺘﺨﺩﺍﻤ ﹰﺎ ﻓـﻲ‬ ‫ﺍﻝﺸﺒﮑﺎﺕ ﺍﻝﻼﺴﻠﮑﻴﺔ‪ ،‬ﻭﻗﺩ ﻁﻭﺭﺕ ﻫﺫﻩ ﺍﻝﺘﻘﻨﻴﺔ ﺃﻭل ﻤﺭﺓ ﻤﻥ ﻗﺒل ﺍﻝﺠﻴﺵ ﺍﻷﻤﺭﻴﮑﻲ ﺨـﻼل‬ ‫ﺍﻝﺤﺭﺏ ﺍﻝﻌﺎﻝﻤﻴﺔ ﺍﻝﺜﺎﻨﻴﺔ ﻝﻤﻨﻊ ﻋﻤﻠﻴﺎﺕ ﺍﻝﺘﺠﺴﺱ ﻋﻠﻰ ﺇﺭﺴﺎل ﺍﻝﺭﺍﺩﻴﻭ‪.‬‬ ‫ﺘﺴﺘﺨﺩﻡ ﺸﺒﮑﺎﺕ ﺭﺍﺩﻴﻭ ﺍﻝﻁﻴﻑ ﺍﻹﻨﺘﺸﺎﺭﻱ ﻋﺩﺓ ﺘﺭﺩﺩﺍﺕ ﻤﻌ ﹰﺎ ﻝﻨﻘل ﺍﻹﺸـﺎﺭﺓ ﻤﻤـﺎ‬ ‫ﻴﻘﻠل ﻤﻥ ﺍﻝﻤﺸﺎﮑل ﺍﻝﻤﺘﻌﻠﻘﺔ ﺒﺎﻹﺭﺴﺎل ﺃﺤﺎﺩﻱ ﺍﻝﺘﺭﺩﺩ‪ .‬ﻭﻫﻨﺎﻙ ﺘﻘﻨﻴﺘﺎﻥ ﺃﺴﺎﺴﻴﺘﺎﻥ ﺘﺴﺘﺨﺩﻤﺎﻥ‬ ‫ﻓﻲ ﺸﺒﮑﺎﺕ ﺭﺍﺩﻴﻭ ﺍﻝﻁﻴﻑ ﺍﻹﻨﺘﺸﺎﺭﻱ ﻫﻤﺎ‪:‬‬ ‫• ﺍﻝﺘﺘﺎﺒﻊ ﺍﻝﻤﺒﺎﺸﺭ ‪.Modulation Direct Sequence‬‬ ‫• ﺍﻝﻘﻔﺯﺍﺕ ﺍﻝﺘﺭﺩﺩﻴﺔ ‪Frequency Hopping.‬‬ ‫ﺘﻌﺘﺒﺭ ﺘﻘﻨﻴﺔ ﺍﻝﺘﺘﺎﺒﻊ ﺍﻝﻤﺒﺎﺸﺭ ﺃﮑﺜﺭ ﺍﺴﺘﺨﺩﺍﻤ ﹰﺎ ﻤﻥ ﺍﻝﺘﻘﻨﻴﺔ ﺍﻷﺨﺭﻯ‪ .‬ﺒﻴﺎﻨﺎﺘﻬﺎ ﺍﻝﻤﺸﻔﺭﺓ‬ ‫ﻋﺒﺭ ﻤﺠﻤﻭﻋﺔ ﻤﻥ ﺘﺭﺩﺩﺍﺕ ﺍﻝﺭﺍﺩﻴﻭ ﻓﻲ ﻨﻔﺱ ﺍﻝﻭﻗﺕ ﻭﺘﻘﻭﻡ ﺃﻴـﻀﺎﹰ ﺒﺈﻀـﺎﻓﺔ ‪ Bits‬ﻤـﻥ‬ ‫ﺍﻝﺒﻴﺎﻨﺎﺕ ﺍﻝﻤﺯﻭﺭﺓ ﺍﻝﺘﻲ ﻝﻴﺱ ﻝﻬﺎ ﺃﻱ ﻓﺎﺌﺩﺓ ﺴﻭﻯ ﺘـﻀﻠﻴل ﺍﻷﺠﻬـﺯﺓ ﺍﻝﻤـﺴﺘﻘﺒﻠﺔ ﻏﻴـﺭ‬ ‫ﺍﻝﻤﺭﺨﺹ ﻝﻬﺎ ﺒﺎﺴﺘﻘﺒﺎل ﻫﺫﻩ ﺍﻝﺒﻴﺎﻨﺎﺕ‪ ،‬ﻭﻴﻁﻠﻕ ﻋﻠﻰ ﻫﺫﻩ ﺍﻝـ ‪ Bits‬ﺍﻝﻤﺯﻭﺭﺓ ﺍﺴﻡ ‪Chips‬‬ ‫ﻭﻴﻌﺭﻑ ﺍﻝﺠﻬﺎﺯ ﺍﻝﻤﺭﺨﺹ ﻝﻪ ﺒﺎﻻﺴﺘﻘﺒﺎل ﻤﺴﺒﻘ ﹰﺎ ﺍﻝﺘﺭﺩﺩﺍﺕ ﺍﻝﺘﻲ ﺴـﺘﺤﺘﻭﻱ ﻋﻠـﻰ‬ ‫ﺒﻴﺎﻨﺎﺕ ﺼﺎﻝﺤﺔ ﻓﻴﻘﻭﻡ ﺒﺠﻤﻊ ﻫﺫﻩ ﺍﻝﺒﻴﺎﻨﺎﺕ ﻭﺍﺴﺘﺒﻌﺎﺩ ﺍﻹﺸﺎﺭﺍﺕ ﻏﻴﺭ ﺍﻝﺼﺎﻝﺤﺔ‪ .‬ﺃﻤـﺎ ﻓـﻲ‬ ‫ﺘﻘﻨﻴﺔ ﺍﻝﻘﻔﺯﺍﺕ ﺍﻝﺘﺭﺩﺩﻴﺔ ‪ Frequency Hopping‬ﻓﺈﻥ ﺍﻹﺸﺎﺭﺍﺕ ﺘﻨﺘﻘل ﺒﺴﺭﻋﺔ ﻤﻥ ﺘﺭﺩﺩ‬ ‫ﺇﻝﻰ ﺁﺨﺭ‪ ،‬ﻭﻴﮑﻭﻥ ﻫﻨﺎﻙ ﺘﻔﺎﻫﻡ ﻤﺴﺒﻕ ﺒﻴﻥ ﺍﻝﺠﻬﺎﺯ ﺍﻝﻤﺭﺴل ﻭﺍﻝﺠﻬـﺎﺯ ﺍﻝﻤـﺴﺘﻘﺒل ﻋﻠـﻰ‬ ‫ﺍﺴﺘﺨﺩﺍﻡ ﻨﻤﻭﺫﺝ ﻤﻌﻴﻥ ﻓﻲ ﺘﻨﻅﻴﻡ ﺍﻝﻘﻔﺯﺍﺕ ﺒﻴﻥ ﺍﻝﺘﺭﺩﺩﺍﺕ ﺍﻝﻤﺨﺘﻠﻔﺔ ﻭﺍﻝﻔﺘﺭﺍﺕ ﺍﻝﺯﻤﻨﻴﺔ ﺍﻝﺘﻲ‬ ‫ﺘﻔﺼل ﺒﻴﻥ ﮑل ﻗﻔﺯﺓ ﻭﺃﺨﺭﻯ‪.‬‬ ‫ﻴﺘﺒﻊ ﮑل ﻤﺼﻨﻊ ﺃﻭ ﻤﻨﺘﺞ ﻨﻤﻭﺫﺠﻪ ﺍﻝﺨﺎﺹ ﻓﻲ ﺍﻝﺨﻭﺍﺭﺯﻤﻴﺔ ﺍﻝﻤﺘﺒﻌﺔ ﻓﻲ ﺍﻝﻘﻔـﺯﺍﺕ‬ ‫ﺍﻝﺘﺭﺩﺩﻴﺔ ﺍﻝﺘﻲ ﻴﺴﺘﺨﺩﻤﻬﺎ ﺍﻝﺠﻬﺎﺯ ﺃﻥ ﺍﻝﻤﺭﺴل ﻭﺍﻝﻤﺴﺘﻘﺒل‪ .‬ﻭﺘﻌﺘﺒﺭ ﺴﻌﺔ ﻨﻁﺎﻕ ﺍﻝﺒﺙ ﻓـﻲ‬ ‫ﺘﻘﻨﻴﺔ ﺍﻝﻘﻔﺯﺍﺕ ﺍﻝﺘﺭﺩﺩﻴﺔ ﺃﮑﺒﺭ ﻤﻨﻬﺎ ﻓﻲ ﺘﻘﻨﻴﺔ ﺍﻝﺘﺘﺎﺒﻊ ﺍﻝﻤﺒﺎﺸـﺭ ﻭﺫﻝـﻙ ﻨﺘﻴﺠـﺔ ﻷﻥ ﮑﻝـ‬

‫‪7‬‬ ‫تو ا‬

‫ھ نا‬

‫ري‬

‫‪Wireless Networks‬‬

‫ﺍﻝﺘﺭﺩﺩﺍﺕ ﻓﻲ ﺍﻝﻨﻁﺎﻕ ﺘﮑﻭﻥ ﻤﺘﺎﺤﺔ ﻝﻼﺴﺘﺨﺩﺍﻡ ﻤﻥ ﻗﺒل ﺘﻘﻨﻴﺔ ﺍﻝﻘﻔﺯﺍﺕ ﺍﻝﺘﺭﺩﺩﻴـﺔ ﺒﻌﮑـﺱ‬ ‫ﺘﻘﻨﻴﺔ ﺍﻝﺘﺘﺎﺒﻊ ﺍﻝﻤﺒﺎﺸﺭ ﺍﻝﺘﻲ ﺘﺴﺘﺨﺩﻡ ﻤﺠﻤﻭﻋﺔ ﻤﻥ ﺍﻝﺘﺭﺩﺩﺍﺕ ﻭﻝﮑﻥ ﻝﻴﺱ ﮑﻠﻬـﺎ‪ .‬ﻭﺘﻌﺘﺒـﺭ‬ ‫ﺃﻨﻅﻤﺔ ﺍﻝﻁﻴﻑ ﺍﻹﻨﺘﺸﺎﺭﻱ ﻤﻌﺘﺩﻝﺔ ﺍﻝﺘﮑﻠﻔﺔ ﻨﺴﺒﻴﺎﹰ ﻭﺫﻝﻙ ﻭﻓﻘ ﹰﺎ ﻝﻸﺠﻬﺯﺓ ﺍﻝﻤﺴﺘﺨﺩﻤﺔ‪.‬‬

‫‪8‬‬ ‫تو ا‬

‫ھ نا‬

‫ري‬

‫‪Wireless Networks‬‬

‫ﺴﺭﻋﺔ ﻨﻘل ﺍﻝﺒﻴﺎﻨﺎﺕ‪:‬‬

‫ﺘﺘﺭﺍﻭﺡ ﺴﺭﻋﺔ ﻨﻘل ﺍﻝﺒﻴﺎﻨﺎﺕ ﻓﻲ ﻫﺫﺍ ﺍﻝﻨﻅﺎﻡ ﻤﺎ ﺒﻴﻥ ‪ 2‬ﻭ ‪ 6‬ﻤﻴﺠﺎﺒﺕ ﻓﻲ ﺍﻝﺜﺎﻨﻴـﺔ‬

‫ﻭﻝﮑﻥ ﻤﻊ ﺍﺴﺘﺨﺩﺍﻡ ﻁﺎﻗﺔ ﺃﮑﺒﺭ ﻭﻨﻁﺎﻕ ﺃﻋﻠﻰ ﻤﻥ ﺍﻝﺘﺭﺩﺩ ﻤﻥ ﺍﻝﻤﻤﮑـﻥ ﺍﻝﺤـﺼﻭل ﻋﻠـﻰ‬ ‫ﺴﺭﻋﺎﺕ ﺃﮑﺒﺭ ﺒﮑﺜﻴﺭ‪ .‬ﻭﻝﮑﻥ ﻨﻅﺭﺍ ﻻﺴﺘﺨﺩﺍﻡ ﻁﺎﻗﺔ ﻤﻨﺨﻔﻀﺔ ﻝﻺﺭﺴـﺎل ﻓـﻲ ﺍﻝـﺸﺒﮑﺎﺕ‬ ‫ﻤﺘﻭﺍﻀﻌﺔ ﺍﻝﺘﮑـﺎﻝﻴﻑ ﻓﺈﻨﻬـﺎ ﺘﮑـﻭﻥ ﻋﺭﻀـﺔ ﻝﻠﺘـﻀﻌﻴﻑ‪ ،‬ﺃﻤـﺎ ﺒﺎﻝﻨـﺴﺒﺔ ﻝﻠﺘـﺩﺍﺨل‬ ‫ﺍﻝﮑﻬﺭﻭﻤﻐﻨﺎﻁﻴﺴﻲ ﻓﻨﻼﺤﻅ ﺃﻥ ﻨﻅﺎﻡ ﺭﺍﺩﻴﻭ ﺍﻝﻁﻴﻑ ﺍﻹﻨﺘﺸﺎﺭﻱ ﻴﻌﺘﺒﺭ ﺃﮑﺜﺭ ﻤﻨﺎﻋﺔ ﻀﺩ ﻫﺫﺍ‬ ‫ﺍﻝﺘﺩﺍﺨل ﻤﻥ ﺍﻷﻨﻅﻤﺔ ﺍﻷﺨﺭﻯ‪ ،‬ﻭﻤﻤﮑﻥ ﺘﻭﻀﻴﺢ ﺫﻝﻙ ﺒﺄﻥ ﺍﻹﺸﺎﺭﺍﺕ ﻴـﺘﻡ ﺒﺜﻬـﺎ ﻋﺒـﺭ‬ ‫ﺘﺭﺩﺩﺍﺕ ﻤﺨﺘﻠﻔﺔ‪ ،‬ﻭﺒﺎﻝﺘﺎﻝﻲ ﻓﺈﻥ ﺃﻱ ﺘﺩﺍﺨل ﻗﺩ ﻴﺘﻡ ﻤﻊ ﺃﺤﺩ ﻫﺫﻩ ﺍﻝﺘﺭﺩﺩﺍﺕ ﺩﻭﻥ ﻏﻴﺭﻫﺎ ﻤﻤﺎ‬ ‫ﻻ ﻴﺅﺜﺭ ﻋﻠﻰ ﺍﻹﺸﺎﺭﺓ ﮑﮑل ﻭﺍﻝﺘﻲ ﺘﮑﻭﻥ ﻤﻭﺯﻋﺔ ﻋﻠﻰ ﺘﺭﺩﺩﺍﺕ ﻤﺨﺘﻠﻔﺔ ﻤﻊ ﻤﻼﺤﻅﺔ ﺃﻨـﻪ‬ ‫ﻤﻊ ﺯﻴﺎﺩﺓ ﻤﻌﺩل ﻨﻘل ﺍﻝﺒﻴﺎﻨﺎﺕ ﻋﺒﺭ ﺍﻝﺘﺭﺩﺩﺍﺕ ﺍﻝﻤﺨﺘﻠﻔﺔ ﻴﺯﺩﺍﺩ ﻤﻌﺩل ﺍﻝﺘﺩﺍﺨل ﻨﻅﺭﹰﺍ ﻝﺯﻴﺎﺩﺓ‬ ‫ﻤﻌﺩل ﺍﺴﺘﺨﺩﺍﻡ ﺍﻝﺘﺭﺩﺩﺍﺕ ﺍﻝﻤﻌﺭﻀﺔ ﻝﻠﺘﺩﺍﺨل ﻓﻲ ﻭﻗﺕ ﻤﻌﻴﻥ‪.‬‬ ‫ﺇﻥ ﺍﻋﺘﺭﺍﺽ ﺇﺸﺎﺭﺍﺕ ﺭﺍﺩﻴﻭ ﺍﻝﻁﻴﻑ ﺍﻹﻨﺘﺸﺎﺭﻱ ﻤﻤﮑﻥ ﻭﻝﮑﻥ ﺍﻝﺘﺠﺴﺱ ﻋﻠﻰ ﻫﺫﻩ‬ ‫ﺍﻹﺸﺎﺭﺍﺕ ﺸﺒﻪ ﻤﺴﺘﺤﻴل ﻭﺨﺎﺼﺔ ﺃﻥ ﺍﻝﻤﺘﺠﺴﺱ ﻻ ﻴﻌﺭﻑ ﺍﻝﺘﺭﺩﺩﺍﺕ ﺍﻝﻤﺨﺘﻠﻔﺔ ﺍﻝﻤﺴﺘﺨﺩﻤﺔ‬ ‫ﻓﻲ ﺍﻹﺭﺴﺎل ﻭﻻ ﻴﻌﺭﻑ ﺍﻝﺘﻔﺭﻴﻕ ﺒﻴﻥ ﺍﻝﺒﻴﺎﻨﺎﺕ ﺍﻝﺼﺎﻝﺤﺔ ﺃﻭ ﻏﻴﺭ ﺍﻝﻁﺎﻝﺤـﺔ‪ .‬ﻭﺘـﺴﺘﺨﺩﻡ‬ ‫ﺒﻌﺽ ﺍﻝﺸﺒﮑﺎﺕ ﺍﻝﻼﺴﻠﮑﻴﺔ ﺍﻝﻀﻭﺀ ﻝﻨﻘل ﺍﻝﺒﻴﺎﻨﺎﺕ ﻭﻫﻲ ﻨﻭﻋﺎﻥ‪:‬‬ ‫• ﺸﺒﮑﺎﺕ ﺍﻷﺸﻌﺔ ﺘﺤﺕ ﺍﻝﺤﻤﺭﺍﺀ‪.‬‬ ‫• ﺸﺒﮑﺎﺕ ﺍﻝﻠﻴﺯﺭ ﻭ ﻫﻲ ﺘﻭﻓﺭ ﺴﺭﻋﺎﺕ ﻋﺎﻝﻴﺔ ﺠﺩﹰﺍ ﻝﮑﻥ ﺘﮑﻠﻔﺘﻬﺎ ﻤﺭﺘﻔﻌﺔ ﺠﺩﹰﺍ ﺃﻴﻀﺎﹰ‪.‬‬ ‫ﺍﻝﺒﻴﺎﻨﺎﺕ ﺒﺎﺴﺘﺨﺩﺍﻡ ﺍﻝﺼﻤﺎﻡ ﺍﻝﺜﻨﺎﺌﻰ ﺒﺎﻋﺙ ﻝﻠﻀﻭﺀ ‪Emitting Diode (LED) Light‬‬ ‫ﺃﻭ ﺍﻝﺼﻤﺎﻡ ﺍﻝﺜﻨﺎﺌﻰ ﻗﺎﺫﻑ ﺍﻝﻠﻴﺯﺭ )‪ .Injection Laser Diode (ILD‬ﮑﻤﺎ ﺃﻥ ﺇﺸﺎﺭﺍﺕ‬ ‫ﺍﻷﺸﻌﺔ ﺘﺤﺕ ﺍﻝﺤﻤﺭﺍﺀ ﻻ ﺘﺴﺘﻁﻴﻊ ﺍﺨﺘﺭﺍﻕ ﺍﻝﺠﺩﺭﺍﻥ ﺃﻭ ﺍﻷﺠﺴﺎﻡ ﺍﻝﺼﻠﺒﺔ ﮑﻤﺎ ﺃﻨﻬﺎ ﺘﻀﻌﻑ‬ ‫ﺇﺫﺍ ﺘﻌﺭﻀﺕ ﻹﻀﺎﺀﺓ ﺸﺩﻴﺩﺓ‪.‬‬

‫‪9‬‬ ‫تو ا‬

‫ھ نا‬

‫ري‬

‫‪Wireless Networks‬‬

‫ﺇﺫﺍ ﺍﻨﻌﮑﺴﺕ ﺇﺸﺎﺭﺍﺕ ﺍﻷﺸﻌﺔ ﺘﺤﺕ ﺍﻝﺤﻤﺭﺍﺀ ﻋﻥ ﺍﻝﺠﺩﺭﺍﻥ ﻓﺈﻨﻬﺎ ﺘﺨـﺴﺭ ﻨـﺼﻑ‬ ‫ﻁﺎﻗﺘﻬﺎ ﻤﻊ ﮑل ﺍﻨﻌﮑﺎﺱ‪ ،‬ﻭﻨﻅﺭﹰﺍ ﻝﻤﺩﺍﻫﺎ ﻭﺜﺒﺎﺘﻬﺎ ﺍﻝﻤﺤﺩﻭﺩ ﻓﺈﻨﻬﺎ ﺘﺴﺘﺨﺩﻡ ﻋﺎﺩﺓ ﻓﻲ ﺍﻝﺸﺒﮑﺎﺕ‬ ‫ﺍﻝﻤﺤﻠﻴﺔ ﺍﻝﺼﻐﻴﺭﺓ‪ .‬ﻭﻴﺘﺭﺍﻭﺡ ﺍﻝﻤﺩﻯ ﺍﻝﺘﺭﺩﺩﻱ ﺍﻝﺫﻱ ﺘﻌﻤل ﻓﻴﻪ ﺍﻷﺸﻌﺔ ﺘﺤﺕ ﺍﻝﺤﻤﺭﺍﺀ ﻤـﺎ‬ ‫ﺒﻴﻥ ‪ 100‬ﻏﻴﻐﺎﻫﺭﺘﺯ ﻭ ‪ 300‬ﺘﻴﺭﺍﻫﺭﺘﺯ‪ .‬ﻭﻨﻅﺭﻴ ﹰﺎ ﺘﺴﺘﻁﻴﻊ ﺍﻷﺸﻌﺔ ﺘﺤﺕ ﺍﻝﺤﻤﺭﺍﺀ ﺘﻭﻓﻴﺭ‬ ‫ﺴﺭﻋﺎﺕ ﺇﺭﺴﺎل ﻋﺎﻝﻴﺔ ﻭﻝﮑﻥ ﻋﻤﻠﻴ ﹰﺎ ﻓﺈﻥ ﺍﻝﺴﺭﻋﺔ ﺍﻝﻔﻌﻠﻴﺔ ﺍﻝﺘﻲ ﺘﺭﺴﻠﻬﺎ ﺃﺠﻬﺯﺓ ﺍﻹﺭﺴـﺎل‬ ‫ﺒﺎﻷﺸﻌﺔ ﺘﺤﺕ ﺍﻝﺤﻤﺭﺍﺀ ﺃﻗل ﻤﻥ ﺫﻝﻙ ﺒﮑﺜﻴﺭ‪ .‬ﻭﺘﻌﺘﻤﺩ ﺘﮑﻠﻔﺔ ﺃﺠﻬﺯﺓ ﺍﻷﺸﻌﺔ ﺘﺤﺕ ﺍﻝﺤﻤﺭﺍﺀ‬ ‫ﻋﻠﻰ ﺍﻝﻤﻭﺍﺩ ﺍﻝﻤﺴﺘﺨﺩﻤﺔ ﻓﻲ ﺘﻨﻘﻴﺔ ﻭﺘﺭﺸﻴﺢ ﺍﻷﺸﻌﺔ ﺍﻝﻀﻭﺌﻴﺔ‪ .‬ﻭﺘﺴﺘﺨﺩﻡ ﺸﺒﮑﺎﺕ ﺍﻹﺭﺴﺎل‬ ‫ﺒﺎﺴﺘﺨﺩﺍﻡ ﺍﻷﺸﻌﺔ ﺘﺤﺕ ﺍﻝﺤﻤﺭﺍﺀ ﺜﻼﺙ ﺘﻘﻨﻴﺎﺕ ﻫﻰ‪:‬‬ ‫• ﻨﻘﻁﺔ ﺇﻝﻰ ﻨﻘﻁﺔ ‪.Point To Point‬‬ ‫• ﺇﺭﺴﺎل ﻤﻨﺘﺸﺭ ﺃﻭ ﺇﺫﺍﻋﻲ ‪.Broadcast‬‬ ‫• ﺍﻹﺭﺴﺎل ﺍﻝﻌﺎﮑﺱ ‪.Reflective‬‬ ‫ﺘﺘﻁﻠﺏ ﺘﻘﻨﻴﺔ ﻨﻘﻁﺔ ﺇﻝﻰ ﻨﻘﻁﺔ ﺨﻁ ﹰﺎ ﻤﺒﺎﺸﺭﹰﺍ ﻴﺴﻤﺢ ﻝﮑل ﻤـﻥ ﺍﻝﺠﻬـﺎﺯ ﺍﻝﻤﺭﺴﻝـ‬ ‫ﻭﺍﻝﻤﺴﺘﻘﺒل ﺭﺅﻴﺔ ﺃﺤﺩﻫﻤﺎ ﺍﻵﺨﺭ ﻝﺫﺍ ﻴﺘﻡ ﺘﺼﻭﻴﺒﻬﻤﺎ ﺒﺩﻗﺔ ﻝﻴﻭﺍﺠﻪ ﮑل ﻤﻨﻬﻤﺎ ﺍﻵﺨﺭ‪ ،‬ﻓﺈﺫﺍ ﻝﻡ‬ ‫ﻴﺘﻭﻓﺭ ﺨﻁ ﻤﺒﺎﺸﺭ ﺒﻴﻥ ﺍﻝﺠﻬﺎﺯﻴﻥ ﻓﺴﻴﻔﺸل ﺍﻻﺘﺼﺎل‪.‬‬ ‫ﻭﻤﺜﺎل ﻋﻠﻰ ﻫﺫﻩ ﺍﻝﺘﻘﻨﻴﺔ ﻫﻭ ﺠﻬﺎﺯ ﺍﻝﺘﺤﮑﻡ ﺒـﺎﻝﺘﻠﻔﺯﻴﻭﻥ‪ .‬ﻭﻨﻅـﺭﺍﹰ ﻝﻠﺤﺎﺠـﺔ ﺇﻝـﻰ‬ ‫ﺍﻝﺘﺼﻭﻴﺏ ﺍﻝﺩﻗﻴﻕ ﻝﻸﺠﻬﺯﺓ ﻓﺈﻥ ﺘﺭﮑﻴﺏ ﻫﺫﻩ ﺍﻷﻨﻅﻤﺔ ﻓﻴﻪ ﺼﻌﻭﺒﺔ‪ .‬ﻭﺘﺘﺭﺍﻭﺡ ﺴﺭﻋﺔ ﻨﻘﻝـ‬ ‫ﺍﻝﺒﻴﺎﻨﺎﺕ ﺒﺎﺴﺘﺨﺩﺍﻡ ﻫﺫﻩ ﺍﻝﺘﻘﻨﻴﺔ ﺒﻴﻥ ﺒﻀﻊ ﮑﻴﻠﻭﺍﺕ ﻤﻥ ‪ Bits‬ﻓﻲ ﺍﻝﺜﺎﻨﻴﺔ ﻭﻗﺩ ﺘﺼل ﺇﻝﻰ ‪16‬‬ ‫ﻤﻴﺠﺎﺒﺕ ﻓﻲ ﺍﻝﺜﺎﻨﻴﺔ ﻋﻠﻰ ﻤﺩﻯ ﮑﻴﻠﻭﻤﺘﺭ ﻭﺍﺤﺩ‪ .‬ﻭﻴﻌﺘﻤﺩ ﻤﻘﺩﺍﺭ ﺍﻝﺘﻀﻌﻴﻑ ﻓـﻲ ﺇﺸـﺎﺭﺍﺕ‬ ‫ﺍﻷﺸﻌﺔ ﺘﺤﺕ ﺍﻝﺤﻤﺭﺍﺀ ﻋﻠﻰ ﮑﺜﺎﻓﺔ ﻭﻭﻀﻭﺡ ﺍﻷﺸﻌﺔ ﺍﻝﻤﺒﺜﻭﺜﺔ ﮑﻤﺎ ﻴﻌﺘﻤﺩ ﻋﻠﻰ ﺍﻝﻅـﺭﻭﻑ‬ ‫ﺍﻝﻤﻨﺎﺨﻴﺔ ﻭﺍﻝﻌﻘﺒﺎﺕ ﻓﻲ ﻁﺭﻴﻕ ﺍﻷﺸﻌﺔ‪ ،‬ﻭﮑﻠﻤﺎ ﮑﺎﻨﺕ ﺍﻷﺸﻌﺔ ﻤﺼﻭﺒﺔ ﺒﺸﮑل ﺃﺩﻕ ﮑﻠﻤﺎ ﻗل‬ ‫ﻤﺴﺘﻭﻯ ﺍﻝﺘﻀﻌﻴﻑ ﮑﻤﺎ ﺃﻨﻪ ﻴﺼﺒﺢ ﻤﻥ ﺍﻝﺼﻌﺏ ﺍﻋﺘﺭﺍﺽ ﺍﻷﺸﻌﺔ ﺃﻭ ﺍﻝﺘﺠﺴﺱ ﻋﻠﻴﻬﺎ‪.‬‬

‫‪10‬‬ ‫تو ا‬

‫ھ نا‬

‫ري‬

‫‪Wireless Networks‬‬

‫ﺃﻤﺎ ﺘﻘﻨﻴﺔ ﺍﻹﺭﺴﺎل ﺍﻝﻤﻨﺘﺸﺭ ﻓﺈﻥ ﺍﻷﺸﻌﺔ ﻴﺘﻡ ﻨﺸﺭﻫﺎ ﻋﻠﻰ ﻤﺴﺎﺤﺔ ﻭﺍﺴﻌﺔ ﻭﻴﻁﻠـﻕ‬ ‫ﻋﻠﻰ ﺸﺒﮑﺎﺕ ﺍﻹﺭﺴﺎل ﺍﻝﻤﻨﺘﺸﺭ ﺃﺤﻴﺎﻨﺎﹰ ﺸﺒﮑﺎﺕ ﺍﻷﺸﻌﺔ ﺘﺤﺕ ﺍﻝﺤﻤﺭﺍﺀ ﺍﻝﻤﺒﻌﺜﺭﺓ ‪Scatter‬‬ ‫‪.Infrared Networks‬‬ ‫ﻭﻫﻨﺎ ﻴﺴﺘﻁﻴﻊ ﺠﻬﺎﺯ ﻭﺍﺤﺩ ﺍﻻﺘﺼﺎل ﻤﻊ ﺃﮑﺜﺭ ﻤﻥ ﺠﻬﺎﺯ ﻓﻲ ﻭﻗﺕ ﻭﺍﺤـﺩ ﻭﻫـﺫﺍ‬ ‫ﺍﻷﻤﺭ ﻴﻌﺘﺒﺭ ﻤﻴﺯﺓ ﻤﻥ ﻨﺎﺤﻴﺔ ﻭﻋﻴﺏ ﻤﻥ ﻨﺎﺤﻴﺔ ﺃﺨﺭﻯ ﺤﻴﺙ ﺃﻨـﻪ ﻴـﺴﻤﺢ ﻻﻋﺘـﺭﺍﺽ‬ ‫ﺍﻹﺸﺎﺭﺓ ﻭﺍﻝﺘﺠﺴﺱ ﻋﻠﻴﻬﺎ‪ .‬ﻭﻨﺠﺩ ﺃﻥ ﺴﺭﻋﺔ ﻨﻘل ﺍﻝﺒﻴﺎﻨﺎﺕ ﻓﻲ ﻫﺫﻩ ﺍﻝﺘﻘﻨﻴﺔ ﺃﻗل ﻤﻨﻬـﺎ ﻓـﻲ‬ ‫ﺍﻝﺘﻘﻨﻴﺔ ﺍﻝﺴﺎﺒﻘﺔ ﻓﻬﻲ ﻻ ﺘﺘﺠﺎﻭﺯ ‪ 1‬ﻤﻴﺠﺎﺒﺕ ﻓﻲ ﺍﻝﺜﺎﻨﻴﺔ ﻭﻤﺭﺸﺤﺔ ﻝﻠﺯﻴﺎﺩﺓ ﻓـﻲ ﺍﻝﻤـﺴﺘﻘﺒ‪،‬ل‬ ‫ﻭﻝﮑﻥ ﻓﻲ ﺍﻝﻤﻘﺎﺒل ﻓﺈﻥ ﺇﻋﺩﺍﺩﻫﺎ ﺃﺴﺭﻉ ﻭﺃﺴﻬل ﻭ ﺃﮑﺜﺭ ﻤﺭﻭﻨﺔ‪ ،‬ﻭﻫﻲ ﺃﻴﻀ ﹰﺎ ﺘﺘـﺄﺜﺭ ﺴـﻠﺒ ﹰﺎ‬ ‫ﺒﺎﻝﻀﻭﺀ ﺍﻝﻤﺒﺎﺸﺭ ﻭﺒﺎﻝﻌﻭﺍﻤل ﺍﻝﺠﻭﻴﺔ‪ ،‬ﻭﻻ ﻴﺘﺠﺎﻭﺯ ﺍﻝﻤﺩﻯ ﺍﻝﺫﻱ ﺘﻐﻁﻴﻪ ﻫـﺫﻩ ﺍﻝﺘﻘﻨﻴـﺔ ﺇﺫﺍ‬ ‫ﮑﺎﻨﺕ ﻁﺎﻗﺘﻬﺎ ﻀﻌﻴﻔﺔ ﺒﻀﻊ ﻋﺸﺭﺍﺕ ﻤﻥ ﺍﻷﻤﺘﺎﺭ‪.‬‬ ‫ﺃﻤﺎ ﺍﻝﻨﻭﻉ ﺍﻝﺜﺎﻝﺙ ﻭﻫﻭ ﺍﻝﻌﺎﮑﺱ ‪ Reflective‬ﻓﻬﻭ ﻋﺒﺎﺭﺓ ﻋـﻥ ﺩﻤـﺞ ﻝﻠﻨـﻭﻋﻴﻥ‬ ‫ﺍﻝﺴﺎﺒﻘﻴﻥ‪ ،‬ﻭﻓﻴﻪ ﻴﻘﻭﻡ ﮑل ﺠﻬﺎﺯ ﺒﺎﻹﺭﺴﺎل ﻨﺤﻭ ﻨﻘﻁﺔ ﻤﻌﻴﻨﺔ ﻭﻓﻲ ﻫـﺫﻩ ﺍﻝﻨﻘﻁـﺔ ﻴﻭﺠـﺩ‬ ‫‪ Transceiver‬ﻴﻘﻭﻡ ﺒﺈﻋﺎﺩﺓ ﺇﺭﺴﺎل ﺍﻹﺸﺎﺭﺓ ﺇﻝﻰ ﺍﻝﺠﻬﺎﺯ ﺍﻝﻤﻁﻠﻭﺏ‪.‬‬

‫‪11‬‬ ‫تو ا‬

‫ھ نا‬

‫ري‬

‫‪Wireless Networks‬‬

‫ﻁﺭﻴﻘﺔ ﺇﻋﺩﺍﺩ ﺸﺒﮑﺔ ﻻﺴﻠﮑﻴﺔ ﺒﺴﻴﻁﺔ‪:‬‬

‫ﺍﻷﻤﺭ ﺃﺒﺴﻁ ﺒﮑﺜﻴﺭ ﻤﻤﺎ ﻴﺘﺼﻭﺭﻩ ﺍﻝﺒﻌﺽ‪ ،‬ﻫﻨﺎ ﺴﻴﺘﻡ ﺸﺭﺡ ﺇﻋﺩﺍﺩ ﺸﺒﮑﺔ ﻻﺴـﻠﮑﻴﺔ‬

‫ﻤﮑﻭﻨﺔ ﻤﻥ ﺠﻬﺎﺯ ﺤﺎﺴﺏ ﻤﻨﺯﻝﻲ ﻭﺠﻬﺎﺯ ﺤﺎﺴﺏ ﻤﺤﻤﻭل ﻭﻨﻘﻁﺔ ﺍﺘـﺼﺎل ﺃﻭ ‪Access‬‬ ‫‪ Point.‬ﮑﻤﺎ ﻫﻭ ﻤﻌﻠﻭﻡ ﻓﻲ ﺍﻝﺸﺒﮑﺎﺕ ﺍﻝﻼﺴﻠﮑﻴﺔ ﺍﻝﻤﮑﻭﻨﺔ ﻤﻥ ‪ 3‬ﺃﺠﻬﺯﺓ ﻤﺜﻼﹰ‪ ،‬ﻓـﺈﻥ ﮑﻝـ‬ ‫ﺠﻬﺎﺯ ﻴﺠﺏ ﺃﻥ ﻴﺤﻭﻱ ﻋﻠﻰ ﮑﺭﺕ ﺸﺒﮑﺔ ﻭﮑل ﺍﻷﺠﻬﺯﺓ ﺘﮑﻭﻥ ﻤﻭﺼـﻠﺔ ﺒﺎﻝــ‪ hub‬ﺃﻭ‬ ‫ﺒﺎﻝـ ‪ switch‬ﻝﻴﺘﻡ ﺘﺒﺎﺩل ﺍﻝﻤﻠﻔﺎﺕ ﻭ ﺍﻝﺒﻴﺎﻨﺎﺕ ﻤﻥ ﺨﻼل ﻭﺤﺩﺓ ﻤﻭﺯﻋﺔ ﻝﻬﻡ‪.‬‬ ‫ﻤﺘﻁﻠﺒﺎﺕ ﺍﻝﺸﺒﮑﺔ ﺍﻝﻼﺴﻠﮑﻴﺔ ﻓﻲ ﻤﺜﺎﻝﻨﺎ ﻫﻲ‪:‬‬ ‫ﻻ ﻨﺄﺨﺫ ﻨﻭﻉ ‪Wireless D-Link USB‬‬ ‫ﮑﺭﺕ ﺸﺒﮑﺔ ﻻﺴﻠﮑﻴﺔ ﻝﻠﺠﻬﺎﺯ ﺍﻝﻤﻨﺯﻝﻲ ﻤﺜﺎ ﹰ‬

‫ﺍﻝﮑﺭﺕ ﺍﻷﻭل ‪ :Wireless D-Link USB Adapter DWL 120,‬ﻫﻭ ﮑـﺭﺕ ﻴـﺘﻡ‬ ‫ﺘﺭﮑﻴﺒﻪ ﺒﺎﻝﺤﺎﺴﺏ ﻝﻴﺘﻤﮑﻥ ﺍﻝﺤﺎﺴﺏ ﻤﻥ ﺍﻻﺘﺼﺎل ﺒﺎﻝﺸﺒﮑﺔ ﺍﻝﻼﺴﻠﮑﻴﺔ ﺍﻝﻤﻭﺠﻭﺩﺓ ﻓـﻲ ﻤـﺩﺍﻩ‬ ‫ﺒﺩﻭﻥ ﺃﺴﻼﻙ!‬ ‫ﻴﺘﻡ ﺘﻭﺼﻴل ﻫﺫﺍ ﺍﻝﮑﺭﺕ ﺒﻭﺍﺴﻁﺔ ﻤﻨﻔﺫ ﺍﻝـ‪ USB‬ﺍﻝﻤﻌﺭﻭﻑ‪ .‬ﮑـﺭﻭﺕ ﺍﻝـﺸﺒﮑﺎﺕ‬ ‫ﺍﻝﻼﺴﻠﮑﻴﺔ ﺍﻝﻤﺴﺘﺨﺩﻤﺔ ﻝﻠﺤﺎﺴﺏ ﻓﻲ ﺍﻝﻤﺎﻀﻲ‪ ،‬ﮑﺎﻥ ﻴﺘﻡ ﺘﻭﺼﻴﻠﻬﺎ ﻤﻥ ﺨﻼل ﮑﺭﺕ ﺨـﺎﺹ‬ ‫ﻤﻥ ﻨﻭﻉ ‪ PCI‬ﻭ ﻻ ﺘﺯﺍل ﻫﺫﻩ ﺍﻝﮑﺭﻭﺕ ﻤﻭﺠﻭﺩﺓ‪ ،‬ﻝﮑﻥ ﻤﻊ ﺘﻁﻭﺭ ﺍﻝﺘﻘﻨﻴـﺔ‪ ،‬ﺘـﻡ ﺇﻨﺘـﺎﺝ‬ ‫ﮑﺭﻭﺕ ﻴﺘﻡ ﺘﻭﺼﻴﻠﻬﺎ ﺒﻤﻨﻔﺫ ﺍﻝـ ‪ USB‬ﺴﺭﻋﺔ ﻫﺫﺍ ﺍﻝﮑﺭﺕ ‪ 11‬ﻤﻴﻐﺎ ﺒﺕ ﻓﻲ ﺍﻝﺜﺎﻨﻴﺔ ﺤﻴﺙ‬ ‫ﺍﻨﻪ ﻴﺴﺎﻭﻱ )ﺘﻘﺭﻴﺒﺎﹰ( ﺴﺭﻋﺔ ﺍﻝﺸﺒﮑﺎﺕ ﺍﻝﺴﻠﮑﻴﺔ )ﺫﺍﺕ ﺍﻝـ ‪ 10‬ﻤﻴﻐﺎ ﺒـﺕ ﻓـﻲ ﺍﻝﺜﺎﻨﻴـﺔ(‪.‬‬

‫‪12‬‬ ‫تو ا‬

‫ھ نا‬

‫ري‬

‫‪Wireless Networks‬‬

‫ﻴﺠﺏ ﺍﺘﺒﺎﻉ ﺍﻝﺨﻁﻭﺍﺕ ﺍﻝﻤﻭﺠﻭﺩﺓ ﻓﻲ ﺍﻝﺩﻝﻴل ﺍﻝﺨﺎﺹ ﺒﺘﻌﺭﻴﻑ ﺍﻝﮑﺭﺕ‪ .‬ﻤﻊ ﻫﺫﺍ ﺍﻝﮑﺭﺕ ﻓﻲ‬ ‫ﺍﻝﺒﺩﺍﻴﺔ ﻴﺘﻡ ﺇﺩﺨﺎل ﺍﻝﻘﺭﺹ ﺍﻝﻤﺩﻤﺞ )ﺍﻝﺴﻲ ﺩﻱ( ﺍﻝﺨﺎﺹ ﺒﺎﻝﮑﺭﺕ ﻭ ﻴﺘﻡ ﺘﺨﺯﻴﻥ ﺍﻝﺒﺭﻨـﺎﻤﺞ‬ ‫ﺍﻝﺨﺎﺹ ﺒﻪ‪ ،‬ﻭ ﺒﻌﺩﻫﺎ ﺴﻴﻁﻠﺏ ﻤﻨﻙ ﺍﻝﺠﻬﺎﺯ ﺇﻋﺎﺩﺓ ﺍﻝﺘﺸﻐﻴل‪.‬‬ ‫ﺍﻵﻥ ﻗﻡ ﺒﺘﻭﺼﻴل ﻭﺼﻠﺔ ﺍﻝـ‪ USB‬ﺒﺎﻝﺤﺎﺴﺏ ﻭ ﺜﻡ ﺸﻐل ﺍﻝﺤﺎﺴـﺏ‪ ,‬ﺴـﻴﺨﺒﺭﻙ‬ ‫ﺍﻝﻭﻴﻨﺩﻭﺯ ﺃﻥ ﻫﻨﺎﻙ ﺠﻬﺎﺯ ﺠﺩﻴﺩ ﺘﻡ ﺘﻭﺼﻴﻠﻪ ﺒﺎﻝﺤﺎﺴﺏ ﻭﻴﺠﺏ ﺘﻌﺭﻴﻔـﻪ‪ ،‬ﺍﮑﻤﻝـ ﻋﻤﻠﻴـﺔ‬ ‫ﺍﻝﺘﻌﺭﻴﻑ ﮑﻤﺎ ﻫﻭ ﻤﻌﺘﺎﺩ‪.‬‬ ‫ﻤﻼﺤﻅﺔ ﻴﺘﻡ ﺘﻭﺼﻴل ﮑﺒل ﺍﻝـ‪ USB‬ﺒﺎﻝﻔﺘﺤﺔ ﺍﻝﺼﻐﻴﺭﺓ ﺍﻝﻤﻭﺠﻭﺩﺓ ﻓﻲ ﻤﻘﺩﻤـﺔ ﺍﻝﮑـﺭﺕ‬ ‫ﻭﺍﻝﻁﺭﻑ ﺍﻵﺨﺭ ﻴﻭﺼل ﺒﺎﻝﺠﻬﺎﺯ‪.‬‬ ‫ﺍﻝﮑﺭﺕ ﺍﻝﺜﺎﻨﻲ ‪ :Wireless D-Link PCMCIA Adapter DWL-650+‬ﻫﻭ ﮑﺭﺕ‬ ‫ﻴﺘﻡ ﺘﺭﮑﻴﺒﻪ ﻓﻲ ﺃﺠﻬﺯﺓ ﺍﻝﺤﺎﺴﺏ ﺍﻝﻤﺤﻤﻭﻝﺔ‪ ،‬ﻓﻬﻭ ﻴﺴﺘﺨﺩﻡ ﻤﻨﻔﺫ ﺍﻝـ ‪ PCMCIA‬ﻁﺭﻴﻘـﺔ‬ ‫ﺘﻌﺭﻴﻔﻪ ﻫﻲ ﻤﺜل ﺍﻝﮑﺭﺕ ﺍﻝﺴﺎﺒﻕ‪ .‬ﻭﻝﻴﺘﻤﮑﻥ ﺍﻝﺤﺎﺴﺏ ﺍﻝﻤﺤﻤﻭل ﻤـﻥ ﺍﻻﺘـﺼﺎل ﺒﺎﻝـﺸﺒﮑﺔ‬ ‫ﺍﻝﻼﺴﻠﮑﻴﺔ ﺍﻝﻤﻭﺠﻭﺩﺓ ﻓﻲ ﻤﺩﺍﻩ ﺒﺩﻭﻥ ﺃﺴﻼﻙ! ﻭ ﺤﺴﺏ ﺍﻝﻨﻭﻋﻴﺔ ﺘﺼل ﺴﺭﻋﺘﻬﺎ ﺇﻝـﻰ ‪22‬‬ ‫ﻤﻴﻐﺎ ﺒﺕ ﻓﻲ ﺍﻝﺜﺎﻨﻴﺔ‪.‬‬ ‫ﻤﻼﺤﻅﺔ‪ :‬ﻴﻤﮑﻥ ﺍﺴﺘﺨﺩﺍﻡ ﺍﻝﮑﺭﺕ ﺍﻷﻭل ﺃﻴﻀ ﹰﺎ‬ ‫ﻤﻨﻔﺫ ‪USB‬‬

‫ﺍﻝﺤﺎﺴﺒﺎﺕ ﺍﻝﻤﺤﻤﻭﻝﺔ ﻓﻲ ﺤـﺎل ﺘـﻭﻓﺭ‬ ‫ﻓﻲ‬

‫ﻨﻘﻁﺔ ﺍﺘﺼﺎ‪،‬ل ﮑﻤﺜﺎل ﻨﺄﺨﺫ ﻨﻭﻉ‪:‬‬ ‫‪Wireless D-Link DWL 900AP+ Access Point‬‬ ‫ﻋﻤل ﻫﺫﺍ ﺍﻝﺠﻬﺎﺯ ﻫﻭ ﻨﻔﺱ ﻋﻤل ﺍﻝـ ‪ HUB‬ﺃﻭ ﺍﻝـ ‪ Switch‬ﻓـﻲ‬ ‫ﺍﻝﺸﺒﮑﺎﺕ ﺍﻝﺴﻠﮑﻴﺔ‪ ،‬ﻓﮑﺭﻭﺕ ﺍﻝﺸﺒﮑﺔ ﻋﻨﺩ ﺘﺸﻐﻴﻠﻬﺎ ﺘﺒﺤﺙ ﻋﻥ ﺃﻱ ﻨﻘﻁﺔ‬ ‫ﺍﺘﺼﺎل ﻓﻲ ﻤﺩﺍﻫﺎ ﻝﺘﺘﺼل ﺒﻪ‪ .‬ﺠﺩﻴﺭ ﺒﺎﻝﺫﮑﺭ ﺃﻥ ﻨﻘﻁﺔ ﺍﻻﺘﺼﺎل ﻝﻴﺴﺕ‬ ‫ﻤﺤﺩﻭﺩﺓ ﺒﻌﺩﺩ ﻤﻌﻴﻥ ﻤﻥ ﺃﺠﻬﺯﺓ ﺍﻝﺤﺎﺴﺏ ﺍﻝﻤﺘﺼﻠﺔ ﺒﻬﺎ‪ ،‬ﻴﻤﮑﻥ ﺘﻭﺼﻴل‬

‫‪13‬‬ ‫تو ا‬

‫ھ نا‬

‫ري‬

‫‪Wireless Networks‬‬

‫ﻋﺩﺩ ﮑﺒﻴﺭ ﻤﻥ ﺍﻷﺠﻬﺯﺓ ﺒﻨﻘﻁﺔ ﺍﺘﺼﺎل ﻭﺍﺤﺩﺓ ﻓﻘﻁ ﺒﺨﻼﻑ ﺍﻝـ‪ hub‬ﺤﻴﺙ ﺍﻨـﻪ ﻤﺤـﺩﻭﺩ‬ ‫ﺒﻌﺩﺩ ﻤﻌﻴﻥ ﻤﻥ ﺍﻝﻤﻨﺎﻓﺫ‪ .‬ﻭﻝﮑﻥ ﻋﻨﺩ ﺍﺭﺘﻔﺎﻉ ﻋﺩﺩ ﺍﻷﺠﻬﺯﺓ ﺍﻝﻤﺘﺼﻠﺔ ﻓﺎﻥ ﺍﻝـﺴﺭﻋﺔ ﺴـﺘﻘل‬ ‫ﻭﺍﻷﺩﺍﺀ ﺴﻴﻀﻌﻑ ﺒﻁﺒﻴﻌﺔ ﺍﻝﺤﺎل‪.‬‬ ‫ﻫﺫﻩ ﺍﻝﺼﻭﺭﺓ ﺘﻭﻀﺢ ﺍﻝﺘﻭﺼﻴل ﺍﻝﺸﺒﮑﻲ ﻓﻲ ﺍﻝﺒﻴﺌﺔ ﺍﻝﻼﺴﻠﮑﻴﺔ‪:‬‬

‫ﻝﮑل ﻨﻘﻁﺔ ﺍﺘﺼﺎل ﻤﺩﻯ ﻤﻌﻴﻥ ﻴﺴﺘﻁﻴﻊ ﺃﻥ ﻴﻐﻁﻴﻪ ﻭﻓﻲ ﻤﺜﺎﻝﻨﺎ ﻓﺎﻥ ﺍﻝﻤﺩﻯ ﻴﺼل ﺇﻝﻰ ‪100‬‬ ‫ﻤﺘﺭ ﺘﻘﺭﻴﺒ ﹰﺎ ﻓﻲ ﺍﻷﻤﺎﮑﻥ ﺍﻝﻤﻔﺘﻭﺤﺔ ﻭﻴﻨﺨﻔﺽ ﺍﻝﻤﺩﻯ ﻓﻲ ﺍﻷﻤﺎﮑﻥ ﺍﻝﺩﺍﺨﻠﻴﺔ‪.‬‬ ‫ﻭﮑﻤﺎ ﺫﮑﺭﻨﺎ ﺴﺎﺒﻘ ﹰﺎ ﻓﺎﻥ ﮑل ﮑﺭﺕ ﻋﻨﺩ ﺘﺸﻐﻴﻠﻪ ﻓﺎﻨﻪ ﻴﺒﺤﺙ ﻋﻥ ﺃﻱ ﻨﻘﻁﺔ ﺍﺘﺼﺎل ﻓﻲ ﻤـﺩﺍﻩ‬ ‫ﮑﻲ ﻴﺘﺼل ﺒﻬﺎ ﻭ ﻫﺫﺍ ﺍﻝﻭﻀـﻊ )ﺍﺘـﺼﺎل ﺍﻝﺤﺎﺴـﺏ ﺒﻨﻘﻁـﺔ ﺍﺘـﺼﺎل( ﻴـﺴﻤﻰ ﺒــ‬ ‫‪ Infrastructure Mode‬ﻴﻤﮑﻥ ﺃﻴﻀﺎ ﺘﻭﺼﻴل ﺠﻬﺎﺯﻴﻥ ﻤﻊ ﺒﻌﻀﻬﻤﺎ ﻤﻥ ﻏﻴﺭ ﻭﺠـﻭﺩ‬ ‫ﻨﻘﻁﺔ ﺍﻻﺘﺼﺎل ﻫﺫﺍ ﺍﻝﻭﻀﻊ ﻴﺴﻤﻰ ‪ Ad Hoc‬ﮑﻤﺎ ﻫﻭ ﻤﺒﻴﻥ ﻓﻲ ﺍﻝﺼﻭﺭﺓ‬

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‫‪Wireless Networks‬‬

‫ﺇﻋﺩﺍﺩﺍﺕ ﻨﻘﻁﺔ ﺍﻻﺘﺼﺎل‪:‬‬ ‫ﺒﻌﺩ ﺍﻻﻨﺘﻬﺎﺀ ﻤﻥ ﺘﻌﺭﻴﻑ ﮑﺭﻭﺕ ﺍﻝﺸﺒﮑﺔ ﻭﺘﺸﻐﻴل ﻨﻘﻁﺔ ﺍﻻﺘﺼﺎل )ﻴﮑﻔﻲ ﺃﻥ ﻨﻭﺼل‬ ‫ﻨﻘﻁﺔ ﺍﻻﺘﺼﺎل ﺒﺎﻝﮑﻬﺭﺒﺎﺀ ﻭ ﺴﺘﻌﻤل ﺒﺎﻹﻋﺩﺍﺩﺍﺕ ﺍﻻﻓﺘﺭﺍﻀﻴﺔ( ﻴﺠﺏ ﺃﻥ ﻨﺨﺘﺎﺭ ﻭﻨﺤﺩﺩ ‪IP‬‬ ‫‪ Address‬ﻝﮑل ﮑﺭﺕ‪ ،‬ﻻﻥ ﺍﻝـ ‪ DHCP Server‬ﺍﻝﻤﻭﺠﻭﺩ ﻓﻲ ﻨﻘﻁﺔ ﺍﻻﺘﺼﺎل ﻏﻴـﺭ‬ ‫ﻤﻔﻌل ﻓﻲ ﺍﻹﻋﺩﺍﺩﺍﺕ ﺍﻻﻓﺘﺭﺍﻀﻴﺔ‪.‬‬ ‫ﻴﺘﻡ ﺘﺤﺩﻴﺩ ﺍﻝـ ‪ IP Address‬ﻝﮑل ﺠﻬﺎﺯ ﻋﻥ ﻁﺭﻴﻕ ﺍﺘﺒﺎﻉ ﺍﻝﺘﻌﻠﻴﻤﺎﺕ ﺍﻝﺘﺎﻝﻴﺔ‪:‬‬ ‫ﺍﺘﺠﻪ ﺇﻝﻰ ‪start‬ﺜﻡ ‪ settings‬ﺜﻡ ‪ control panel‬ﺜﻡ ‪Network and dial up‬‬ ‫‪ connections,‬ﺍﻵﻥ ﺒﺎﻝﺯﺭ ﺍﻷﻴﻤﻥ ﺍﻨﻘﺭ ﻨﻘﺭﺓ ﻋﻠﻰ ﺍﻝـ ‪Local Area Connection‬‬ ‫ﺍﻝﺫﻱ ﺘﻡ ﻋﻤﻠﻪ ﻝﮑﺭﺕ ﺍﻝﺸﺒﮑﺔ ﺍﻝﻼﺴﻠﮑﻴﺔ ﻭ ﺴﺘﺤﺼل ﻋﻠﻰ ﺍﻝﺘﺎﻝﻲ‪:‬‬

‫ﺍﻨﻘﺭ ﻨﻘﺭﺘﻴﻥ ﻋﻠﻰ ‪ Internet Protocol -TCP/IP‬ﻭﻨﺴﺠل ﺭﻗﻡ ﺍﻝـ ‪ IP‬ﻭﻗﻨﺎﻉ ﺍﻝﺸﺒﮑﺔ‪.‬‬

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‫‪Wireless Networks‬‬

‫ﻁﺒﻌ ﹰﺎ ﻴﻤﮑﻥ ﺘﻐﻴﻴﺭ ﺭﻗﻡ ﺍﻝـ ‪ IP‬ﺇﻝﻰ ﺭﻗﻡ ﺸﺒﻴﻪ ﻝﮑﻥ ﻫﺫﺍ ﻤﺠﺭﺩ ﻤﺜﺎل‪ .‬ﺍﻵﻥ ﺍﻀﻐﻁ‬ ‫ﻤﺭﺘﻴﻥ ﻋﻠﻰ ‪ OK‬ﻭ ﺃﻋﺩ ﺘﺸﻐﻴل ﺍﻝﺠﻬﺎﺯ ﺇﻥ ﻁﻠﺏ ﻤﻨﻙ ﺫﻝﻙ‪ .‬ﺍﻋﺩ ﻨﻔﺱ ﺍﻝﻌﻤﻠﻴﺔ ﻤﻊ ﺍﻝﺠﻬﺎﺯ‬ ‫ﺍﻵﺨﺭ ﻤﻊ ﺘﻐﻴﻴﺭ ﺭﻗﻡ ﺍﻝـ‪ IP‬ﺇﻝﻰ ﻤﺜﻼ ‪ .192.168.0.8‬ﻻﺤﻅ ﺃﻨﻨﺎ ﻏﻴﺭﻨﺎ ﺍﻝﺨﺎﻨﺔ ﺍﻷﺨﻴﺭﺓ‬ ‫ﻭﻫﻲ ﺍﻝﺨﺎﺼﺔ ﺒﺭﻗﻡ ﺍﻝﺠﻬﺎﺯ ﻋﻠﻰ ﺍﻝﺸﺒﮑﺔ‪.‬‬ ‫ﺍﻵﻥ ﺃﺼﺒﺤﺕ ﺠﺎﻫﺯ ﻝﻼﺘﺼﺎل ﺒﺎﻝﺸﺒﮑﺔ ﺍﻝﻼﺴﻠﮑﻴﺔ‪ .‬ﻭﻴﻤﮑﻨﻨﺎ ﻤﻌﺭﻓﺔ ﻤﻌﻠﻭﻤﺎﺕ ﻋﻥ‬ ‫ﺤﺎﻝﺔ ﺍﻝﺸﺒﮑﺔ ﻤﻥ ﺨﻼل ﺍﻝﺒﺭﺍﻤﺞ ﺍﻝﻤﺭﺍﻓﻘﺔ ﻝﻠﺘﺠﻬﻴﺯﺍﺕ ﻭﻝﻨﺘـﺎﺒﻊ ﻤـﻊ ﺍﻝﺘﺠﻬﻴـﺯﺍﺕ ﺍﻝﺘـﻲ‬ ‫ﺍﺨﺘﺭﻨﺎﻫﺎ ﻭﻫﺫﻩ ﻭﺍﺠﻬﺔ ﺍﻝﺒﺭﻨﺎﻤﺞ ﺍﻝﺘﻲ ﺴﺘﺨﺒﺭﻙ ﺒﺤﺎﻝﺔ ﺍﻝﺸﺒﮑﺔ ﺍﻝﻼﺴﻠﮑﻴﺔ‪:‬‬

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‫‪Wireless Networks‬‬

‫ﻝﻨﺸﺭﺡ ﻤﺎ ﺘﺤﺘﻭﻱ ﺍﻝﺼﻭﺭﺓ ﻤﻥ ﺃﻤﻭﺭ‪:‬‬ ‫‪Status : Associated BSSID=00-08-C8-AC-7F-E0‬‬ ‫ﻫﺫﻩ ﺘﻌﻨﻲ ﺃﻥ ﮑﺭﺕ ﺍﻝﺸﺒﮑﺔ ﺍﻝﻼﺴﻠﮑﻴﺔ ﻤﺘﺼل ﺒﻨﻘﻁﺔ ﺍﻻﺘﺼﺎل ﺍﻝﺘﻲ ﺘﺤﻤل ﻋﻨﻭﺍﻥ ﺍﻝـ‬ ‫‪ MAC Address‬ﺍﻝﺘﺎﻝﻲ‪00-08-C8-AC-7F-E0 :‬‬ ‫ﻭﺍﻝـ ‪ MAC Address‬ﻫﻭ ‪ Media Access Control Address‬ﻭﻫـﻭ ﺍﻝﻌﻨـﻭﺍﻥ‬ ‫ﺍﻝﻔﻴﺯﻴﺎﺌﻲ ﻝﮑﺭﺕ ﺍﻝﺸﺒﮑﺔ ﺍﻝﻼﺴﻠﮑﻴﺔ‬ ‫ﺍﻻﺘﺼﺎل ﺘﺤﺘﻭﻱ ﻋﻠﻰ ﮑﺭﺕ ﺸـﺒﮑﺔ ﻻﺴـﻠﮑﻲ‬ ‫ﻓﻨﻘﻁﺔ‬ ‫ﺒﺩﺍﺨﻠﻬﺎ‪ ،‬ﻭﻫﺫﺍ ﺍﻝﻌﻨﻭﺍﻥ ﻋﻨﻭﺍﻥ ﺜﺎﺒﺕ ﻴﺄﺘﻲ ﻤﻥ ﺍﻝﺸﺭﮑﺔ ﺍﻝﻤﺼﻨﻌﺔ ﻭﻴﮑﻭﻥ ﺍﻝﺭﻗﻡ ﺭﻗﻡ ﻤﻤﻴﺯ‬ ‫ﻤﻥ ﺍﻝﻤﻔﺘﺭﺽ ﺃﻥ ﻴﻤﻠﻙ ﮑل ﮑﺭﺕ ﺸﺒﮑﺔ ﺴﻭﺍﺀ ﺴﻠﮑﻲ ﺃﻭ ﻻﺴﻠﮑﻲ ﺭﻗﻡ ﺨﺎﺹ ﺒﻪ ﻻ ﻴﺘﮑﺭﺭ‬ ‫ﻤﻊ ﮑﺭﻭﺕ ﺃﺨﺭﻯ ﻴﻌﻁﻰ ﻤﻥ ﺍﻝﺸﺭﮑﺔ ﺍﻝﻤﻨﺘﺠﺔ‪.‬‬

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‫‪Wireless Networks‬‬

‫‪SSID‬‬ ‫ﻭﻫﻭ ﺍﻝـ ‪ Service Set IDentifier‬ﻭﻫﻭ ﺭﻗﻡ ﺃﻭ ﻤﻌﺭﻑ ﻝﻨﻘﻁﺔ ﺍﻻﺘﺼﺎل‪ .‬ﮑل‬ ‫ﻨﻘﻁﺔ ﺍﺘﺼﺎل ﻝﺩﻴﻬﺎ ﻤﻌﺭﻑ ﺨﺎﺹ ﺒﻬﺎ ﺘﺭﺴﻠﻪ ﺒﺸﮑل ﻤﺴﺘﻤﺭ ﮑﻲ ﺘﻠﺘﻘﻁﻪ ﮑﺭﻭﺕ ﺍﻝـﺸﺒﮑﺔ‬ ‫ﺍﻝﻼﺴﻠﮑﻴﺔ ﺍﻝﻤﻭﺠﻭﺩﺓ ﻓﻲ ﻤﺩﺍﻫﺎ ﻝﺘﻌﺭﻑ ﻫﺫﻩ ﺍﻝﮑﺭﻭﺕ ﺃﻥ ﻨﻘﻁﺔ ﺍﺘـﺼﺎل ﺫﺍﺕ ﺍﻝﻤﻌـﺭﻑ‬ ‫ﺍﻝﻔﻼﻨﻲ ﻤﻭﺠﻭﺩﺓ ﻓﻲ ﻤﺩﺍﻫﺎ‪ .‬ﻤﻥ ﺍﻝﻨﺎﺤﻴﺔ ﺍﻷﻤﻨﻴﺔ ﻴﻔﻀل ﺘﻌﻁﻴل ﺨﺎﺼﻴﺔ ﺇﺭﺴﺎل ﺍﻝﻤﻌـﺭﻑ‬ ‫ﻤﻥ ﻨﻘﻁﺔ ﺍﻻﺘﺼﺎل ﻷﻨﻪ ﺇﺫﺍ ﮑﺎﻥ ﺍﻝﻤﺩﻯ ﺒﻌﻴﺩ ﻨﺴﺒﻴﺎﹰ ﻓﺎﻥ ﺃﻱ ﺸﺨﺹ ﻴﻤﮑﻨﻪ ﺍﻝﺩﺨﻭل ﻝﻠﺸﺒﮑﺔ‬ ‫ﺍﻝﺨﺎﺼﺔ ﺒﻙ ﺒﺩﻭﻥ ﻋﻨﺎﺀ ﻤﻌﺭﻓﺔ ﺭﻗﻡ ﺍﻝﻤﻌﺭﻑ ﺍﻝﺨﺎﺹ ﺒﺎﻝﺸﺒﮑﺔ!‬ ‫ﻓﺒﺸﮑل ﺍﻓﺘﺭﺍﻀﻲ ﻤﻊ ﺸﺭﮑﺔ ‪ D LINK‬ﻓﺎﻥ ﺍﻝﻤﻌﺭﻑ ﻴﮑﻭﻥ ﮑﻠﻤﺔ ‪ default‬ﻴﻤﮑﻥ‬ ‫ﺃﻥ ﺘﻐﻴﺭﻫﺎ ﻷﻱ ﮑﻠﻤﺔ ﺃﻭ ﺭﻗﻡ ﺘﺸﺎﺀ‪.‬‬ ‫‪Tx Rate‬‬ ‫ﻭﻫﻭ ﻤﻌﺩل ﺍﻝﺴﺭﻋﺔ ﺍﻝﻤﺘﻭﻓﺭﺓ ﻝﻠﮑﺭﺕ ﻓﻲ ﻫﺫﻩ ﺍﻝﻤﺴﺎﻓﺔ‪ .‬ﮑﻠﻤﺎ ﺒﻌﺩ ﺍﻝﺠﻬـﺎﺯ ﻋـﻥ‬ ‫ﻨﻘﻁﺔ ﺍﻻﺘﺼﺎل ﻗﻠﺕ ﺴﺭﻋﺔ ﺍﻝﻨﻘل‪.‬‬ ‫‪Channel‬‬ ‫ﺍﻝﻘﻨﺎﺓ ﺍﻝﺘﻲ ﻴﺘﻡ ﺍﻻﺘﺼﺎل ﺒﻬﺎ ﺒﻴﻥ ﮑﺭﺕ ﺍﻝﺸﺒﮑﺔ ﻭ ﻨﻘﻁﺔ ﺍﻻﺘﺼﺎل ﻭﻴﻤﮑﻥ ﺍﺨﺘﻴـﺎﺭ‬ ‫ﺭﻗﻡ ‪ 6 , 3 , 1‬ﺃﻭ ‪.11‬‬ ‫‪Link Quality‬‬ ‫ﻭﻫﻲ ﺠﻭﺩﺓ ﺍﻻﺘﺼﺎل ﺇﺫﺍ ﮑﻨﺕ ﻤﺘﺼل ﺒﺤﺎﺴﺏ ﻤﻌﻴﻥ ﻓﻲ ﺍﻝﺸﺒﮑﺔ ﺍﻝﻼﺴﻠﮑﻴﺔ ﻭﮑﻨﺕ‬ ‫ﺘﻨﻘل ﻤﻠﻑ ﻤﻌﻴﻥ ﻓﺎﻥ ﻫﺫﺍ ﺍﻷﻤﺭ ﻴﺒﻴﻥ ﻝﻙ ﺠﻭﺩﺓ ﺍﻻﺘﺼﺎل ﺒﻴﻨﻙ ﻭ ﺒﻴﻥ ﺍﻝﺠﻬﺎﺯ ﺍﻵﺨﺭ ﻓـﻲ‬ ‫ﺍﻝﻠﺤﻅﺔ ﺫﺍﺘﻬﺎ‪.‬‬

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‫‪Wireless Networks‬‬

‫‪Signal Strength‬‬ ‫ﻭﻫﻲ ﻗﻭﺓ ﺍﻹﺭﺴﺎل ﮑﻠﻤﺎ ﺍﺒﺘﻌﺩﺕ ﻋﻥ ﻨﻘﻁﺔ ﺍﻻﺘﺼﺎل ﮑﻠﻤﺎ ﻀﻌﻑ ﺍﻹﺭﺴﺎل‪.‬‬ ‫‪Data Rate‬‬ ‫ﻴﺒﻴﻥ ﻋﻠﻰ ﺸﮑل ﺭﺴﻭﻡ ﺒﻴﺎﻨﻴﺔ ﺤﺭﮑﺔ ﻨﻘل ﺍﻝﻤﻠﻔﺎﺕ ﺒﻴﻥ ﺍﻷﺠﻬﺯﺓ ﺒﺎﻝـﻀﻐﻁ ﻋﻠـﻰ‬ ‫‪ SiteSurvey‬ﺍﻝﻤﻭﺠﻭﺩ ﻋﻠﻰ ﺍﻝﻴﺴﺎﺭ ﻴﻤﮑﻨﻨﺎ ﻤﺸﺎﻫﺩﺓ ﻨﻘﺎﻁ ﺍﻻﺘﺼﺎل ﺍﻝﻤﻭﺠﻭﺩﺓ ﻓﻲ ﻤـﺩﻯ‬ ‫ﮑﺭﺕ ﺍﻝﺸﺒﮑﺔ ﻨﺴﺘﻁﻴﻊ ﺍﺨﺘﻴﺎﺭ ﻨﻘﻁﺔ ﺍﻻﺘﺼﺎل ﺍﻝﻤﺭﺍﺩ ﺍﻻﺘﺼﺎل ﺒﻬﺎ ﻭﺍﻝﺩﺨﻭل ﻓﻲ ﺍﻝـﺸﺒﮑﺔ‬ ‫ﺍﻝﺨﺎﺼﺔ ﺒﻬﺎ )ﻓﻲ ﺤﺎل ﻭﺠﻭﺩ ﺍﮑﺜﺭ ﻤﻥ ﻨﻘﻁﺔ ﺍﺘﺼﺎل ﻓﻲ ﻨﻔﺱ ﺍﻝﻤﻨﻁﻘﺔ( ﻨﻅﻠﻠﻬﺎ ﻭﻨﻀﻐﻁ‬ ‫ﻋﻠﻰ ‪ Connect‬ﻓﻴﻘﻭﻡ ﮑﺭﺕ ﺍﻝﺸﺒﮑﺔ ﺒﺎﻻﺘﺼﺎل ﺒﻨﻘﻁﺔ ﺍﻻﺘﺼﺎل ﻫﺫﻩ ﺍﻝـﺼﻭﺭﺓ ﺘﻭﻀـﺢ‬ ‫ﻨﻘﻁﺔ ﺍﺘﺼﺎل ﻭﺍﺤﺩﺓ ﻤﻭﺠﻭﺩﺓ ﻓﻲ ﻨﻔﺱ ﺍﻝﻤﺩﻯ‪:‬‬

‫ﻭﻤﻥ ﺍﻝﺠﺩﻴﺭ ﺒﺎﻝﺫﮑﺭ ﺃﻥ ﻫﻨﺎﻙ ﺒﻌﺽ ﺍﻷﻤﻭﺭ ﺍﻝﺘﻲ ﺘﻌﻴﻕ ﻭﺘﻀﻌﻑ ﺍﻹﺭﺴﺎل ﻓـﻲ‬ ‫ﻨﻘﻁﺔ ﺍﻻﺘﺼﺎل‪ .‬ﻤﻨﻬﺎ ﺃﻥ ﻴﮑﻭﻥ ﺍﻝﺤﺎﺴﺏ ﺒﻌﻴﺩﹰﺍ ﻋﻥ ﻨﻘﻁﺔ ﺍﻻﺘﺼﺎ‪،‬ل ﻭﺍﻥ ﻴﮑﻭﻥ ﺍﻝﻔﺎﺼﻝـ‬ ‫ﺒﻴﻨﻬﻤﺎ ﺠﺩﺭﺍﻥ ﻋﺩﻴﺩﺓ ﺴﻭﺍﺀ ﺇﺴﻤﻨﺘﻴﺔ ﺃﻭ ﻤﻥ ﻏﻴﺭﻩ‪ ،‬ﻭﻭﺠﻭﺩ ﻋﺩﺓ ﺃﺠﻬﺯﺓ ﮑﻬﺭﺒﺎﺌﻴﺔ ﺘﻌﻤﻝـ‬ ‫ﻓﻲ ﻨﻔﺱ ﻤﮑﺎﻥ ﻨﻘﻁﺔ ﺍﻻﺘﺼﺎل ﮑﺸﺎﺸﺔ ﺍﻝﺤﺎﺴﺏ ﻭﻏﻴﺭﻫﺎ‪ ،‬ﻭﻗﺭﺏ ﺍﻝﻤﻨﺯل ﻤـﻥ ﻤﺤﻁـﺔ‬

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‫‪Wireless Networks‬‬

‫ﺘﻘﻭﻴﺔ ﺇﺭﺴﺎل ﻝﺸﺭﮑﺔ ﺍﻻﺘﺼﺎﻻﺕ ﺃﻭ ﺍﻝﻤﻁﺎﺭ ﻭﺨﻼﻓﻪ‪ .‬ﮑل ﻫﺫﻩ ﺍﻷﻤﻭﺭ ﺘﺅﺜﺭ ﺴﻠﺒ ﹰﺎ ﻓﻲ ﻗﻭﺓ‬ ‫ﺇﺭﺴﺎل ﻨﻘﻁﺔ ﺍﻻﺘﺼﺎل ﻓﻴﺠﺏ ﺘﺠﻨﺒﻬﺎ ﻗﺩﺭ ﺍﻹﻤﮑﺎﻥ ﻝﻠﺤﺼﻭل ﻋﻠﻰ ﺍﻓﻀل ﺘﻐﻁﻴﺔ‪.‬‬

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‫‪Wireless Networks‬‬

‫ﺯﻴﺎﺩﺓ ﻗﻭﺓ ﺍﻹﺸﺎﺭﺓ ﻓﻲ ﺍﻝﺸﺒﮑﺎﺕ ﺍﻝﻼﺴﻠﮑﻴﺔ‪:‬‬ ‫ﻝﻠﻭﺼﻭل ﺇﻝﻰ ﺫﻝﻙ ﻨﺘﺒﻊ ﻫﺫﻩ ﺍﻝﻤﻼﺤﻅﺎﺕ‪:‬‬

‫• ﺍﻝﻤﻭﻗﻊ‬

‫ﻫﺫﻩ ﻨﻘﻁﻪ ﻤﻬﻤﺔ ﺠﺩﺍ ﺤﻴﺙ ﺇﻥ ﺍﻝﻤﻭﻗﻊ ﻴﻠﻌﺏ ﺩﻭﺭﹰﺍ ﺃﺴﺎﺴﻴ ﹰﺎ ﻓﻲ ﺍﻻﺘﺼﺎل ﻭﻗﻭﺓ ﺍﻹﺸﺎﺭﺓ ﮑﻤﺎ‬

‫ﻨﻌﻠﻡ ﻓﺈﻨﻪ ﮑﻠﻤﺎ ﺯﺍﺩ ﺍﻝﺒﻌﺩ ﻋﻥ ﻨﻘﻁﺔ ﺍﻝﻭﺼﻭل " ‪ " access point‬ﺘﻘﻝـ ﻗـﻭﺓ ﺍﻹﺸـﺎﺭﺓ‬ ‫ﻭﺃﻴﻀ ﹰﺎ ﮑﻠﻤﺎ ﺯﺍﺩﺕ ﺍﻝﻌﻭﺍﺌﻕ ﺍﻝﻁﺒﻴﻌﻴﺔ ﻤﺎ ﺒﻴﻥ ﻨﻘﻁﺔ ﺍﻝﻭﺼﻭل ﻭﺍﻝﻤـﺴﺘﺨﺩﻡ ﺃﻴـﻀﺎ ﺘﻘﻝـ‬ ‫ﺍﻹﺸﺎﺭﺓ ﻝﺫﻝﻙ ﻋﻠﻴﻨﺎ ﺒﺎﻝﺘﻔﮑﻴﺭ ﻓﻲ ﺍﻝﻤﮑﺎﻥ ﻭﺍﻝﻤﻭﻗﻊ ﻭﺍﻝﻤﻭﻀﻊ ﺍﻷﻨﺴﺏ ﻝﻭﻀﻊ ﺠﻬﺎﺯ ﺍﻝــ‬ ‫‪ access point‬ﺒﻪ‪.‬‬

‫• ﺍﻝﺤﻭﺍﺠﺯ ﻭﺍﻝﻤﻭﺍﻨﻊ‪:‬‬

‫ﻫﻲ ﺍﻝﺤﻭﺍﺠﺯ ﺍﻝﻤﺎﺩﻴﺔ ﻭﺍﻝﻤﻌﺩﻨﻴﺔ ﻭﺍﻝﺤﺠﺭﻴﺔ ﻓﻬﻲ ﺘﺅﺜﺭ ﻋﻠﻰ ﺍﻝﻤﻭﺠﻪ ﺒﺸﮑل ﮑﺒﻴﺭ ﺠﺩﹰﺍ ﻭﻗﺩ‬ ‫ﺘﻘﻁﻌﻬﺎ ﻨﻬﺎﺌﻴﺎﹰ ﻭﻝﺫﻝﻙ ﻻ ﺘﺠﻌل ‪ access point‬ﻗﺭﻴﺒ ﹰﺎ ﻤﻥ ﺇﻱ ﻤﻨﻬﺎ ﺃﻭ ﻤﻼﺼﻕ ﻝﻬﺎ ﺤﺘـﻰ‬ ‫ﻻ ﺘﺘﻌﺭﺽ ﺍﻝﻤﻭﺠﻪ ﺇﻝﻰ ﺍﻝﻘﻁﻊ ﺃﻭ ﺍﻝﻀﻌﻑ‪.‬‬

‫• ﻏﻴﺭ ﺍﻝﻬﻭﺍﺌﻲ‪:‬‬

‫ﻨﻘﻁﻪ ﻤﻬﻤﺔ ﺠﺩﹰﺍ ﻭﻫﻲ ﻝﻴﺴﺕ ﻋﻴﺏ ﻓﻲ ﺍﻝﺘﺼﻨﻴﻊ ﻭﺇﻨﻤﺎ ﺤﺴﺏ ﺍﻝﻬﻨﺩﺴﺔ ﺍﻝﺸﺨﺼﻴﺔ ﻝﻌﻤﻠﻴـﺔ‬ ‫ﺍﻻﺘﺼﺎل ﻓﮑﻤﺎ ﻨﻌﻤل ﺃﻥ ﮑل ﺍﻝـ ‪ access point‬ﺍﻝﺘﻲ ﺘﺒﺎﻉ ﻓﻲ ﺍﻷﺴﻭﺍﻕ ﺘﻤﻠﻙ ﻫﻭﺍﺌﻲ ﺃﻭ‬ ‫ﺍﺜﻨﻴﻥ ‪ omni-directional‬ﻭﻫﻲ ﻤﻥ ﺍﻝﻨﻭﻋﻴﺎﺕ ﺍﻝﺘﻲ ﺘﻘﻭﻡ ﺒﺼﻨﻊ ﻤﻭﺠﻪ ﻋﻠﻰ ﺸﮑل ﺩﺍﺌﺭﺓ‬

‫ﮑﺎﻤﻠﺔ ﺫﺍﺕ ﻨﺼﻑ ﻗﻁﺭ ﻗﺩ ﻴﮑﻭﻥ ﻤﻔﻴﺩﺍ ﺒﺎﻝﻨﺴﺒﺔ ﻝﻙ ﺍﺴﺘﺨﺩﺍﻡ ﻤﺜل ﻫﺫﺍ ﺍﻝﻬﻭﺍﺌﻲ ﻓﻲ ﺤـﺎل‬ ‫ﮑﺎﻥ ‪ access point‬ﻓﻲ ﻤﻨﺘﺼﻑ ﺍﻷﺠﻬﺯﺓ ﺍﻝﻤﺘﺼﻠﺔ ﺒﻪ ﺤﻴﺙ ﺴﻴﻘﻭﻡ ﺒﺘﻐﻁﻴـﻪ ﺍﻝـﺩﺍﺌﺭﺓ‬ ‫ﺍﻝﻤﺤﻴﻁﺔ ﺒﻪ ﻝﮑﻥ ﻤﺎﺫﺍ ﻝﻭ ﮑﺎﻥ ﻝﺩﻴﻙ ‪ access point‬ﻓﻲ ﺍﻝﻐﺭﻓﺔ ﺍﻷﺨﻴﺭﺓ ﻓﻲ ﺍﻝﺒﻴﺕ ﻭﺒﻘﻴﺔ‬ ‫ﺍﻷﺠﻬﺯﺓ ﺍﻝﻤﺘﺼﻠﺔ ﻓﻲ ﺍﻝﻐﺭﻑ ﺍﻝﻤﺠﺎﻭﺭﺓ ؟؟ ﻓﻲ ﻫﺫﻩ ﺍﻝﺤﺎﻝﺔ ﺴﻨﮑﻭﻥ ﺒﺤﺎﺠﺔ ﺇﻝﻰ ﻫـﻭﺍﺌﻲ‬

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‫‪Wireless Networks‬‬

‫ﺃﻭ ﻝﺼﺤﻥ ﻻﻗﻁ ﺨﺎﺭﺠﻲ ﺇﻻ ﺃﻨﻪ ﻴﺘﻌﺎﻤل ﻤﻊ ﺍﻹﺸﺎﺭﺓ ﺒﺸﮑل ﻤﻭﺠﻪ )ﻤﺨﺭﻭﻁﻲ( ﻭﻝـﻴﺱ‬ ‫ﺒﺸﮑل ﺩﺍﺌﺭﻱ‪.‬‬

‫• ﻤﮑﺭﺭ ﺇﺭﺴﺎل" ‪: " Wireless Repeater‬‬ ‫ﮑﻠﻤﺎ ﺯﺍﺩﺕ ﺍﻝﻤﺴﺎﻓﺔ ﺯﺍﺩﺕ ﻨﺴﺒﺔ ﺍﻝﺨﻁﺄ ﺒﺸﮑل ﻋﺎﻡ ﻭﻫﻭ ﻨﻔﺱ ﺍﻝﺤﺎل ﻤﻊ ﺍﻝـﺸﺒﮑﺎﺕ‬ ‫ﺍﻝﻼﺴﻠﮑﻴﺔ ﻓﺒﺩﻻﹰ ﻤﻥ ﺸﺭﺍﺀ ‪ Access Point‬ﺁﺨﺭ ﺴﻨﻘﻭﻡ ﺒﺸﺭﺍﺀ ‪Wireless Repeater‬‬ ‫ﻝﻠﻐﺭﻓﺔ ﺍﻝﺘﻲ ﻻ ﺘﺼﻠﻬﺎ ﺍﻹﺸﺎﺭﺓ ﺒﺸﮑل ﮑﺎﻓﻲ ﻭﺴﺘﻌﻭﺩ ﺍﻹﺸﺎﺭﺓ ﺇﻝﻰ ﻨﻔﺱ ﺍﻝﻘﻭﻩ ﺍﻝﺘﻲ ﮑﺎﻨﺕ‬ ‫ﻋﻠﻴﻪ‪.‬‬

‫• ﺘﻐﻴﻴﺭ ﻗﻨﺎﺓ ﺍﻹﺸﺎﺭﺓ‪:‬‬ ‫ﮑﻤﺎ ﻨﻌﻠﻡ ﻓﺈﻥ ﺍﻝـ ‪ Access Point‬ﻴﻌﻤل ﻤﺘﻭﺍﻓﻘ ﹰﺎ ﻤﻥ ‪ 11‬ﻗﻨﺎﺓ ﺍﺘـﺼﺎل ﻭﻴﻨـﺼﺢ‬ ‫ﺒﺎﺴﺘﺨﺩﺍﻡ ﻗﻨﻭﺍﺕ ﺭﺍﺩﻭﻴﻪ ﻗﻠﻴﻠﺔ ﺍﻻﺴﺘﺨﺩﺍﻡ ﻓﻲ ﺍﻝﻤﺤﻴﻁ ﻝﻠﺘﻘﻠﻴل ﻤﻥ ﻨﺴﺒﺔ ﺍﻝﺨﻁﺄ ﻓﻲ ﺍﻹﺸﺎﺭﺓ‬ ‫ﻭﺒﺈﻤﮑﺎﻨﻙ ﺍﻝﺩﺨﻭل ﺇﻝﻰ ﻝﻭﺤﺔ ﺍﻝﺘﺤﮑﻡ ﺍﻝﺨﺎﺹ ﺒﺎﻝـ ‪ Access Point‬ﻭﺘﻐﻴﻴﺭ ﺍﻝﻘﻨﺎﺓ ﺤﺘـﻰ‬ ‫ﺘﺼل ﺇﻝﻰ ﻗﻨﺎﺓ ﺘﻌﻁﻴﻙ ﺇﺸﺎﺭﺓ ﺍﻓﻀل ﻭﻻ ﺘﺤﺘﺎﺝ ﺇﻝﻰ ﺍﻝﺘﻌﺩﻴل ﻓﻲ ﺠﻬﺎﺯ ﺍﻝﮑﻤﺒﻴﻭﺘﺭ ﺤﻴـﺙ‬ ‫ﺃﻥ ﺍﻝﮑﺭﻭﺕ ﺘﻘﻭﻡ ﺒﻠﻘﻁ ﺍﻹﺸﺎﺭﺓ ﻭﻤﺤﻁﺘﻬﺎ ﺃﻭﺘﻭﻤﺎﺘﻴﮑﻴﹰﺎ‪.‬‬

‫• ﺃﺒﻌﺩ ﻫﺫﻩ ﺍﻷﺠﻬﺯﺓ ﻋﻨﻙ‪:‬‬ ‫ﻨﻌﻠﻡ ﺒﺄﻥ ﺍﻝـ ‪ Access Point‬ﺍﻝﺤﺩﻴﺜﺔ ﺘﻌﻤل ﻋﻠﻰ ﺒﺭﻭﺘﻭﮑﻭل ‪ b‬ﺃﻭ ‪ g‬ﻭﺍﻝﺘﻲ ﺘﻌﻤل‬ ‫ﻋﻠﻰ ﺇﺸﺎﺭﺓ ﻗﺩﺭﺘﻬﺎ ‪ 2400‬ﻤﻴﺠﺎ ﻫﻴﺭﺘﺯ ﺃﻤﺎ ﺒﺭﻭﺘﻭﮑﻭل ‪ a‬ﻓﻬﻭ ﻴﻌﻤل ﻋﻠﻰ ﺇﺸﺎﺭﺓ ﻗـﺩﺭﺘﻬﺎ‬ ‫‪ 5000‬ﻤﻴﺠﺎ ﻫﻴﺭﺘﺯ ﻭﻫﻨﺎﻙ ﺍﻝﻌﺩﻴﺩ ﻤﻥ ﺍﻷﺠﻬﺯﺓ ﮑﺎﻝﻤﺎﻴﮑﺭﻭﻭﻴﻑ ﻭﺍﻝﺘﻠﻔﻭﻨـﺎﺕ ﺍﻝﻼﺴـﻠﮑﻴﺔ‬ ‫ﻭﺒﻌﺽ ﺍﻷﺠﻬﺯﺓ ﺍﻷﺨﺭﻯ ﮑﺄﺠﻬﺯﺓ‬

‫ﺍﻝﺒﻠﻭﺘﻭﺙ ﻭﺍﻝﺠﻭﺍل ﻗﺩ ﺘﻘـﻭﻡ ﺒﻌﻤﻝـ ﺘـﺩﺍﺨل ﻤـﻊ‬

‫ﺍﻹﺸﺎﺭﺍﺕ ﺍﻝﻤﺭﺴﻠﺔ ﻤﻥ ﺍﻝـ ‪ Access Point‬ﻭﺘﻘﻭﻡ ﺒﺯﻴﺎﺩﺓ ﻨﺴﺒﺔ ﺍﻝﺘﺸﻭﻴﺵ " ‪" noise‬‬ ‫ﺤﺘﻰ ﻗﺩ ﺘﻘﻁﻊ ﺍﻻﺘﺼﺎل ﻓﻲ ﺒﻌﺽ ﺍﻷﺤﻴﺎﻥ ﺒﻴﻥ ﺍﻝﻤﺴﺘﺨﺩﻡ ﻭﺍﻝـ ‪ Access Point‬ﻭﻝﺫﻝﻙ‬ ‫ﻴﻔﻀل ﺃﻥ ﺘﺒﺤﺙ ﻋﻥ ﺃﺠﻬﺯﻩ ﻻ ﺘﻌﻤل ﻓﻲ ﺍﻝﻤﺠﺎل ﺍﻝﺨﺎﺹ ﺒﻙ‪.‬‬

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‫ري‬

‫‪Wireless Networks‬‬

‫• ﺘﺤﺩﻴﺙ ﺘﻌﺭﻴﻑ ﮑﺭﺕ ﺍﻝﺸﺒﮑﺔ ﺍﻝﻼﺴﻠﮑﻲ‪:‬‬ ‫ﺇﻥ ﺍﻝﺸﺭﮑﺎﺕ ﺍﻝﺘﻲ ﺘﻘﻭﻡ ﺒﺈﻨﺘﺎﺝ ﺘﻌﺭﻴﻔﺎﺕ ﻝﻸﺠﻬﺯﺓ‪ ،‬ﺘﻘﻭﻡ ﺃﻴﻀ ﹰﺎ ﺒﺈﺼﻼﺡ ﺃﺨﻁﺎﺀ ﺍﻝﺘﻌﺭﻴﻔﺎﺕ‬ ‫ﺍﻝﺴﺎﺒﻘﺔ ﺃﻭ ﺇﻀﺎﻓﺔ ﺨﺩﻤﺎﺕ ﺠﺩﻴﺩﻩ ﻗﺩ ﺘﻔﻴﺩ ﻓﻲ ﺘﻘﻭﻴﻪ ﺍﻹﺸﺎﺭﺓ ﺒﺸﮑل ﺍﻓﻀل‪.‬‬ ‫ﻝﺫﺍ ﻓﻤﻥ ﺍﻝﻀﺭﻭﺭﻱ ﻤﺘﺎﺒﻌﺔ ﻫﺫﻩ ﺍﻷﻤﻭﺭ ﻭﺇﺠﺭﺍﺀ ﺍﻝﺘﺤﺩﻴﺜﺎﺕ ﺍﻝﻤﻨﺎﺴﺒﺔ ﺒﺸﮑل ﺩﺍﺌﻡ‪.‬‬

‫• ﺘﻭﺤﻴﺩ ﺍﻝﺸﺭﮑﺔ ﺍﻝﻤﻨﺘﺠﺔ ﻋﻥ ﺍﻝﺘﺠﻬﻴﺯ‪:‬‬ ‫ﻻ ﻨﺴﺘﻁﻴﻊ ﺍﻝﻘﻭل ﺒﺄﻥ ﺍﻝﺘﺠﻴﺯﺍﺕ ﺘﮑﻭﻥ ﻏﻴﺭ ﻤﺘﻭﺍﻓﻘﺔ ﻓﻲ ﺤﺎل ﺍﺨﺘﻴﺎﺭﻨﺎ ﺇﻝﻰ ﻋﺩﺓ‬ ‫ﻤﺼﺎﺩﺭ ﻝﻬﺎ ﻭﻝﮑﻥ ﻤﻥ ﺍﻷﻓﻀل ﺩﻭﻤ ﹰﺎ ﻓﻲ ﺤﺎﻝﺔ ﺍﻝﺸﺒﮑﺎﺕ ﺒﺸﮑل ﻋﺎﻡ ﻤﺤﺎﻭﻝﺔ ﺘﻭﺤﻴﺩ‬ ‫ﺍﻝﻤﺼﺎﺩﺭ ﺍﻝﻤﻌﺘﻤﺩﺓ ﻝﻠﺘﺠﻬﻴﺯﺍﺕ ﻝﺘﺤﻘﻴﻕ ﺍﻝﺘﻭﺍﻓﻘﻴﺔ ﺍﻷﻤﺜل ﻭﮑﺫﻝﻙ ﻝﺴﻬﻭﻝﺔ ﺍﻝﺨﺩﻤﺎﺕ‬ ‫ﻭﺍﻝﺘﺤﺩﻴﺜﺎﺕ‪.‬‬

‫• ﻗﻡ ﺒﺘﺤﺩﻴﺙ ﺒﺭﻭﺘﻭﮑﻭل ‪ b 802.11‬ﺇﻝﻰ ‪802.11g‬‬ ‫ﻤﻥ ﺍﻝﻤﺘﻌﺎﺭﻑ ﻋﻠﻴﻪ ﺃﻥ ﺘﻘﻨﻴﺔ ‪b 802.11‬ﻫﻲ ﺍﻷﮑﺜﺭ ﺍﻨﺘﺸﺎﺭﺍﹰ ﻓﻲ ﺍﻝﻌﺎﻝﻡ ﺤﻴﺙ ﺃﻨﻬﺎ ﺠﺎﺀﺕ‬ ‫ﺒﻌﺩ ﺍﺴﺘﻘﺭﺍﺭ ﺘﻘﻨﻴﺔ ‪ Hi-Fi‬ﻭﻝﮑﻥ ﻓﻲ ﻨﻔﺱ ﺍﻝﻭﻗﺕ ﺘﻌﺘﺒﺭ ﻤﺘﺨﻠﻔﺔ ﻋـﻥ ﺘﻘﻨﻴـﺔ ‪g 802.11‬‬ ‫ﺍﻷﺤﺩﺙ ﻭﺍﻝﺘﻲ ﺘﻌﺩ ﺃﺴﺭﻉ ﺒﺨﻤﺱ ﺃﻀﻌﺎﻑ ﻤﻥ ﺘﻘﻨﻴﺔ ‪ b 802.11‬ﻓﺎﻥ ﻝﻡ ﺘﮑﻥ ﺴﻌﻴﺩﹰﺍ ﻤـﻊ‬ ‫ﺘﻘﻨﻴﺔ ‪ 802.11‬ﻗﻡ ﺒﺘﻐﻴﻴﺭ ﮑﺭﻭﺘﻙ ﻭﺍﻝـ ‪ Access Point‬ﺍﻝﺨﺎﺹ ﺒـﻙ ﺇﻝـﻰ ﺘﻘﻨﻴـﺔ‬ ‫‪b‬‬ ‫‪ g 802.11‬ﻤﻊ ﺍﻝﻌﻠﻡ ﺃﻥ ﻫﻨﺎﻙ ﺘﻭﺍﻓﻘﻴﻪ ﻋﺎﻝﻴﺔ ﺒﻴﻥ ﺍﻝﺘﻘﻨﻴﺘﻴﻥ ﻨﻅﺭﹰﺍ ﻷﻨﻬﻤﺎ ﻴﻌﻤﻼﻥ ﻓﻲ ﻨﻔﺱ‬ ‫ﺍﻝﻘﺩﺭﺓ ‪ 2400‬ﻤﻴﺠﺎ ﻫﻴﺭﺘﺯ ﻭﻝﮑﻥ ﻴﻨﺼﺢ ﺒﺎﻝﺘﺭﻗﻴﺔ ﻝﺯﻴﺎﺩﺓ ﺍﻝﻘﻭﻩ ﻓﻲ ﺍﻷﺩﺍﺀ‪.‬‬

‫‪23‬‬ ‫تو ا‬

‫ھ نا‬

‫ري‬

‫‪Wireless Networks‬‬

‫ا ‪ %‬ا * ﻧ&‪ :‬و!( ا'ر! ل ا ‪ & %‬وا ! &‬ ‫ﺘﻘﻊ ﻭﺴﺎﺌﻁ ﺍﻹﺭﺴﺎل ﺘﺤﺕ ﻓﺌﺘﻴﻥ ﺭﺌﻴﺴﻴﺘﻴﻥ ﻫﻤﺎ‪:‬‬ ‫‪ -1‬ﻭﺴﺎﺌﻁ ﺴﻠﮑﻴﺔ‪.‬‬ ‫‪ -2‬ﻭﺴﺎﺌﻁ ﻻﺴﻠﮑﻴﺔ‪.‬‬ ‫ﺍﻝﻭﺴﺎﺌﻁ ﺍﻝﺴﻠﮑﻴﺔ ﺘﮑﻭﻥ ﺇﻤﺎ ﻤﻥ ﺃﺴﻼﻙ ﻤﻌﺩﻨﻴﺔ ﺃﻭ ﺃﻝﻴﺎﻑ ﻭﺘﻭﺼل ﺍﻝﮑﻬﺭﺒﺎﺀ ﻭﺍﻝـﻀﻭﺀ‬ ‫ﻋﻠﻰ ﺍﻝﺘﻭﺍﻝﻲ‪.‬‬ ‫ﺃﻤﺎ ﺍﻹﺭﺴﺎل ﺍﻝﻼﺴﻠﮑﻲ ﻓﻴﺴﺘﺨﺩﻡ ﺍﻝﻐﻼﻑ ﺍﻝﺠﻭﻱ ﮑﻭﺴﻁ ﺇﺭﺴﺎل ﻝﻨﻘل ﺍﻹﺸﺎﺭﺓ‪.‬‬ ‫• ﺘﺘﻀﻤﻥ ﺍﻝﻭﺴﺎﺌﻁ ﺍﻝﻼﺴﻠﮑﻴﺔ‪:‬‬ ‫‪ -1‬ﻤﻭﺠﺎﺕ ﺍﻝﺭﺍﺩﻴﻭ‪.‬‬ ‫‪ -2‬ﻤﻭﺠﺎﺕ ﺍﻝﻤﻴﮑﺭﻭﻭﻴﻑ‪.‬‬ ‫‪ -3‬ﺍﻷﺸﻌﺔ ﺘﺤﺕ ﺍﻝﺤﻤﺭﺍﺀ‪.‬‬ ‫ﺘﺴﺘﺨﺩﻡ ﺍﻝﻭﺴﺎﺌﻁ ﺍﻝﺴﻠﮑﻴﺔ ﻋﺎﺩﺓ ﻓﻲ ﺍﻝﺸﺒﮑﺎﺕ ﺍﻝﻤﺤﻠﻴﺔ ﺍﻝﺼﻐﻴﺭﺓ ﺃﻤـﺎ ﻓـﻲ ﺍﻝـﺸﺒﮑﺎﺕ‬ ‫ﺍﻝﻭﺍﺴﻌﺔ ﻓﺘﺴﺘﺨﺩﻡ ﻤﺠﻤﻭﻋﺔ ﻤﻥ ﺍﻝﻭﺴﺎﺌﻁ ﺍﻝﺴﻠﮑﻴﺔ ﻭﺍﻝﻼﺴﻠﮑﻴﺔ‪.‬‬ ‫ﮑﻤﺎ ﻤﻥ ﺍﻝﻤﻤﮑﻥ ﺍﺴﺘﺨﺩﺍﻡ ﺍﻝﻭﺴﺎﺌﻁ ﺍﻝﻼﺴﻠﮑﻴﺔ ﻝﺘﺤﻘﻴﻕ ﺍﻻﺘـﺼﺎل ﺒـﻴﻥ ﺍﻝﮑﻤﺒﻴـﻭﺘﺭﺍﺕ‬ ‫ﺍﻝﻤﺤﻤﻭﻝﺔ ﻭﺍﻝﺸﺒﮑﺎﺕ ﺍﻝﻤﺤﻠﻴﺔ‪.‬‬

‫‪24‬‬ ‫تو ا‬

‫ھ نا‬

‫ري‬

‫‪Wireless Networks‬‬

‫ﻭﻗﺒل ﺃﻥ ﻨﺤﺩﺩ ﻭﺴﻁ ﺍﻹﺭﺴﺎل ﺍﻷﻨﺴﺏ ﻝﻠﺸﺒﮑﺔ ﻋﻠﻴﻨﺎ ﺍﻹﺠﺎﺒﺔ ﻋﻠﻰ ﻫﺫﻩ ﺍﻷﺴﺌﻠﺔ‪:‬‬ ‫‪ -1‬ﻤﺎ ﻫﻭ ﻤﻘﺩﺍﺭ ﺜﻘل ﺃﻭ ﺍﺯﺩﺤﺎﻡ ﺤﺭﮑﺔ ﺍﻝﻤﺭﻭﺭ ﺍﻝﻤﺘﻭﻗﻊ ﻋﻠﻰ ﺍﻝﺸﺒﮑﺔ؟‬ ‫‪ -2‬ﻤﺎ ﻫﻲ ﺍﻝﻤﺴﺎﻓﺔ ﺍﻝﺘﻲ ﻋﻠﻰ ﻭﺴﻁ ﺍﻻﺘﺼﺎل ﺘﻐﻁﻴﺘﻬﺎ ﺃﻭ ﺍﻝﻭﺼﻭل ﺇﻝﻴﻬﺎ؟‬ ‫‪ -3‬ﻤﺎ ﻫﻲ ﺍﻻﺤﺘﻴﺎﺠﺎﺕ ﺍﻷﻤﻨﻴﺔ ﻝﻠﺸﺒﮑﺔ؟‬ ‫‪ -4‬ﻤﺎ ﻫﻲ ﺍﻝﻤﻴﺯﺍﻨﻴﺔ ﺍﻝﻤﺨﺼﺼﺔ ﻝﻭﺴﻁ ﺍﻻﺘﺼﺎ؟ل‬ ‫ﺃﻤﺎ ﺍﻻﻋﺘﺒﺎﺭﺍﺕ ﺍﻝﺘﻲ ﺘﺅﺜﺭ ﻋﻠﻰ ﺴﻌﺭ ﻭﺃﺩﺍﺀ ﻭﺴﻁ ﺍﻹﺭﺴﺎل ﻓﺘﺘﻀﻤﻥ‪:‬‬ ‫‪ -1‬ﺴﻬﻭﻝﺔ ﺍﻹﻋﺩﺍﺩ ﻭﺍﻝﺘﺭﮑﻴﺏ‪.‬‬ ‫‪-1‬ﻤﺩﻯ ﺴﻌﺔ ﻨﻁﺎﻕ ﺍﻝﺒﺙ‪.‬‬ ‫ﺒﺸﮑل ﻋﺎﻡ ﻓﺈﻥ ﺘﮑﻠﻔﺔ ﻭﺴﻁ ﺍﻹﺭﺴﺎل ﺘﺭﺘﻔﻊ ﻤﻊ ﺍﺭﺘﻔـﺎﻉ ﺴـﺭﻋﺘﻪ ﻭﻨﻘﺎﻭﺘـﻪ‬ ‫ﻭﻤﺩﻯ ﻤﺴﺘﻭﻯ ﺃﻤﻨﻪ‪.‬‬ ‫ﻴﻌﺒﺭ ﻋﻥ ﻤﺩﻯ ﺍﻝﺘﺭﺩﺩﺍﺕ ﺍﻝﻤﻘﺎﺴﻪ ﺒﺎﻝﻬﻴﺭﺘﺯ ﻭﺍﻝﺘﻲ ﻴﺴﺘﻁﻴﻊ ﻭﺴﻁ ﺍﻹﺭﺴـﺎل‬ ‫ﻓﻴﺯﻴﺎﺌﻴﺎﹰ ﺍﺴﺘﻴﻌﺎﺒﻬﺎ ﺒﺴﻌﺔ ﻨﻁﺎﻕ ﺍﻝﺒﺙ ‪ .bandwidth‬ﻭﻫﻲ ﺘﻌﺭﻑ ﺒـﺎﻝﻔﺭﻕ ﺒـﻴﻥ‬ ‫ﺃﻋﻠﻰ ﺍﻝﺘﺭﺩﺩﺍﺕ ﻭﺃﺨﻔﻀﻬﺎ ﻭﺍﻝﺘﻲ ﻴﺴﺘﻁﻴﻊ ﻭﺴﻁ ﺍﻹﺭﺴﺎل ﺤﻤﻠﻬﺎ‪.‬‬ ‫ﻫﺫﻩ ﺍﻝﺴﻌﺔ ﻗﺩ ﺘﺘﻔﺎﻭﺕ ﻭﻓﻘ ﹰﺎ ﻝﻠﻤﺴﺎﻓﺔ ﻭﺘﻘﻨﻴﺔ ﺒﺙ ﺍﻹﺸﺎﺭﺓ ﺍﻝﻤﺴﺘﺨﺩﻤﺔ‪.‬‬ ‫‪-2‬ﻀﻌﻑ ﺍﻹﺸﺎﺭﺓ ‪. attenuation‬‬ ‫ﻴﻌﺭﻑ ﺍﻝـ ‪ attenuation‬ﺒﺄﻨﻪ ﻗﺎﺒﻠﻴﺔ ﺍﻝﻤﻭﺠﺎﺕ ﺍﻝﮑﻬﺭﻭﻤﻐﻨﺎﻁﻴﺴﻴﺔ ﻝﻠﻀﻌﻑ ﻭﺍﻝﺘﻼﺸﻲ‬ ‫ﺨﻼل ﺍﻹﺭﺴﺎل‪.‬‬

‫‪25‬‬ ‫تو ا‬

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‫ري‬

‫‪Wireless Networks‬‬

‫ﻭﺨﻼل ﻤﺭﻭﺭ ﺍﻝﻤﻭﺠﺎﺕ ﺍﻝﮑﻬﺭﻭﻤﻐﻨﺎﻁﻴﺴﻴﺔ ﻓﻲ ﻭﺴﻁ ﺍﻹﺭﺴﺎل ﻴﺘﻌﺭﺽ ﺠـﺯﺀ ﻤـﻥ‬ ‫ﻁﺎﻗﺘﻬﺎ ﻝﻼﻤﺘﺼﺎﺹ ﻭﺍﻝﺒﻌﺜﺭﺓ ﺒﺴﺒﺏ ﺍﻝﺨﻭﺍﺹ ﺍﻝﻔﻴﺯﻴﺎﺌﻴﺔ ﻝﻠﻭﺴﻁ‪.‬‬ ‫ﻴﺠﺏ ﺍﻻﻨﺘﺒﺎﻩ ﻝﻬﺫﺍ ﺍﻷﻤﺭ ﺨﺎﺼﺔ ﻋﻨﺩ ﺍﻝﺘﺨﻁﻴﻁ ﻻﺴﺘﺨﺩﺍﻡ ﻭﺴﻁ ﻤﺎ ﻤﻥ ﺍﻝﻤﻔـﺭﻭﺽ ﺃﻥ‬ ‫ﻴﻐﻁﻲ ﻤﺴﺎﺤﺔ ﺸﺎﺴﻌﺔ‪.‬‬ ‫ﻻ ﺘﺴﺘﻁﻴﻊ ﺃﻏﻠﺏ ﻭﺴﺎﺌﻁ ﺍﻹﺭﺴﺎل ﻋﺯل ﺍﻝﻤﻭﺠﺎﺕ ﺍﻝﮑﻬﺭﻭﻤﻐﻨﺎﻁﻴﺴﻴﺔ ﻋﻥ ﺍﻝﺘﺩﺍﺨل ﻤﻊ‬ ‫ﻤﻭﺠﺎﺕ ﺨﺎﺭﺠﻴﺔ‪.‬‬ ‫‪ -4‬ﺍﻝﻤﻨﺎﻋــــــﺔ ﻤــــــﻥ ﺍﻝﺘــــــﺩﺍﺨل ﺍﻝﮑﻬﺭﻭﻤﻐﻨﺎﻁﻴــــــﺴﻲ‬ ‫‪immunity from electromagnetic interference.‬‬ ‫ﻴﺤﺩﺙ ﺍﻝﺘﺩﺍﺨل ﺍﻝﮑﻬﺭﻭﻤﻐﻨﺎﻁﻴﺴﻲ ﻋﻨﺩﻤﺎ ﺘﻘﻭﻡ ﻤﻭﺠﺎﺕ ﮑﻬﺭﻭﻤﻐﻨﺎﻁﻴﺴﻴﺔ ﻏﻴﺭ ﻤﺭﻏﻭﺏ‬ ‫ﺒﻬﺎ ﺒﺎﻝﺘﺄﺜﻴﺭ ﻋﻠﻰ ﺍﻹﺸﺎﺭﺓ ﺍﻝﻤﻨﻘﻭﻝﺔ ﻋﺒﺭ ﻭﺴﻁ ﺍﻹﺭﺴﺎل‪.‬‬ ‫ﮑﻤﺎ ﺃﻨﻪ ﻤﻥ ﺍﻝﺴﻬل ﺍﻋﺘﺭﺍﺽ ﺍﻝﻤﻭﺠﺎﺕ ﺍﻝﮑﻬﺭﻭﻤﻐﻨﺎﻁﻴﺴﻴﺔ ﻭﺍﻝﺘﺼﻨﺕ ﻋﻠﻴﻬﺎ ﻭﻫـﺫﺍ ﺃﻤـﺭ‬ ‫ﺨﻁﻴﺭ ﺇﺫﺍ ﮑﺎﻨﺕ ﺸﺒﮑﺘﻙ ﺘﺤﺘﻭﻱ ﻋﻠﻰ ﻤﻌﻠﻭﻤﺎﺕ ﺤﺴﺎﺴﺔ‪.‬‬

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‫ري‬

‫‪Wireless Networks‬‬

‫ا ‪ %‬ا * ‪ :+‬ا "‬

‫ا ھ‬

‫‪VPN‬‬

‫ﺍﻝﺸﺒﮑﺔ ‪ VPN‬ﻤﻥ ﺍﻝﻨﺎﺤﻴﺔ ﺍﻝﻨﻅﺭﻴﺔ ﻫﻲ ﺭﺒﻁ ﻋﻤﻴل ﺒﻌﻴﺩ ﺒﻤﻠﻘﻡ ‪ VPN‬ﻋﻥ ﻁﺭﻴﻕ‬ ‫ﺍﻹﻨﺘﺭﻨﺕ‪ ،‬ﺸﺒﮑﺔ ﺍﻹﻨﺘﺭﻨﺕ ﺒﮑل ﺍﻝﺒﻨﻴﺔ ﺍﻝﺘﺤﺘﻴﺔ ﻫﻲ ﺍﻝﻭﺴﻴﻁ ﺒﻴﻥ ﺍﻝﻌﻤﻴل ﻭﻤﻠﻘـﻡ ‪. VPN‬‬ ‫ﻭﻴﮑﻭﻥ ﺍﻻﺭﺘﺒﺎﻁ ﺒﻴﻥ ﺍﻝﺤﺎﺴﺒﻴﻥ ﮑﻤﺎ ﻝﻭ ﮑﺎﻨﻭﺍ ﻓﻲ ﺸﺒﮑﺔ ﺨﺎﺼﺔ ﺤﻘﻴﻘﻴﺔ ﻤﻘﻔﻠﺔ‪ ،‬ﻭﻴﻤﮑﻥ ﺃﻥ‬ ‫ﻴﮑﻭﻥ ﻫﺫﺍ ﺍﻻﺘﺼﺎل ﺒﻴﻥ ﻓﺭﻋﻴﻥ ﺃﻭ ﺸﺭﮑﺎﺀ ﻋﻤل‪.‬‬ ‫ﺘﺘﻡ ﻤﺼﺎﺩﻗﺔ ﺍﺘﺼﺎﻻﺕ ﺍﻝﺸﺒﮑﺔ ﺍﻝﺨﺎﺼﺔ ﺍﻝﻅﺎﻫﺭﻴﺔ )‪ (VPN‬ﺍﻝﺘـﻲ ﺘـﻡ ﺘﻤﮑـﻴﻥ‬ ‫‪ PPTP‬ﻭ‪ L2TP‬ﻋﻠﻴﻬﺎ ﺒﺎﺴﺘﺨﺩﺍﻡ ﺃﺴﺎﻝﻴﺏ ‪PPP‬‬ ‫ﻴﺘﻀﻤﻥ ﺒﺭﻭﺘﻭﮑﻭل ﻤﺼﺎﺩﻗﺔ ﮑﻠﻤﺔ ﺍﻝﻤﺭﻭﺭ‬

‫ﻤـﺴﺘﻭﻯ ﺍﻝﻤـﺴﺘﺨﺩﻡ‪ .‬ﻫـﺫﺍ‬ ‫ﻝﻤﺼﺎﺩﻗﺔ‬ ‫ﻭﺒﺭﻭﺘﻭﮑـﻭل ﺍﻝﻤـﺼﺎﺩﻗﺔ ﻝﺘﻌـﺎﺭﻑ‬ ‫‪،PAP‬‬

‫ﺍﻻﺭﺘﻴـ ﺎﺏ ‪ ،CHAP‬ﻭﺒﺭﻭﺘﻭﮑـﻭل ‪ Shiva‬ﻝﻤـﺼﺎﺩﻗﺔ ﮑﻠﻤـﺔ ﺍﻝﻤـ ﺭﻭﺭ )‪،(SPAP‬‬ ‫ﻭﺒﺭﻭﺘﻭﮑـﻭل ﺍﻝﻤـﺼﺎﺩﻗﺔ ﻝﺘﻌـﺎﺭﻑ ﺍﻻﺭﺘﻴـﺎﺏ )‪ (MS CHAP‬ﻝــ ‪،Microsoft‬‬ ‫ﻭﺒﺭﻭﺘﻭﮑﻭل ﺍﻝﻤﺼﺎﺩﻗﺔ ﺍﻝﻘﺎﺒل ﻝﻺﻝﺤﺎﻕ ‪ EAP‬ﮑﺨﻴﺎﺭ ﺇﻀﺎﻓﻲ‪.‬‬

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‫ري‬

‫‪Wireless Networks‬‬

‫ﺒﺎﺴﺘﺨﺩﺍﻡ ﺨﻴﺎﺭﺍﺕ ﺃﻤﺎﻥ ﺒﺭﻭﺘﻭﮑﻭل ﺇﻨﺘﺭﻨﺕ ‪ IPSec‬ﻭﺒﺭﺘﻭﮑﻭل ﺍﻝﻤﺼﺎﺩﻗﺔ ﺍﻝﻘﺎﺒل‬ ‫ﻝﻺﻝﺤﺎﻕ )‪ (EAP‬ﺍﻝﺠﺩﻴﺩ‪ ،‬ﺘﻭﻓﺭ ﺸﺒﮑﺔ ﺍﻻﺘﺼﺎل ﺍﻝﺨﺎﺼـﺔ ﺍﻝﻅﺎﻫﺭﻴـﺔ ﺃﻤـﺎﻥ ﻤﺤـﺴﻥ‬ ‫ﻝﻠﻤﺴﺘﺨﺩﻤﻴﻥ ﺍﻝﺒﻌﻴﺩﻴﻥ‪ .‬ﻋﻠﻰ ﺴﺒﻴل ﺍﻝﻤﺜﺎ‪،‬ل ﺇﺫﺍ ﺘﻡ ﺘﮑﻭﻴﻥ ﻤﻠﻘﻡ ﺍﻝﻭﺼﻭل ﺍﻝﺒﻌﻴـﺩ ﻝﻁﻠـﺏ‬ ‫‪ EAP‬ﻝﻠﻤﺼﺎﺩﻗﺔ‪ ،‬ﻴﺘﻡ ﻓﺭﺽ ﺍﻝﻤﺴﺘﻭﻯ ﺍﻷﻋﻠﻰ ﻤﻥ ﺍﻝﻤﺼﺎﺩﻗﺔ ﻻﺘﺼﺎﻻﺕ ﺍﻝﻁﻠﺏ ﺍﻝﻬﺎﺘﻔﻲ‬ ‫ﻭﻻﺘﺼﺎﻻﺕ ﺸﺒﮑﺔ ﺍﻻﺘﺼﺎل ﺍﻝﻅﺎﻫﺭﻴﺔ ﻝﻤﻠﻘﻡ ﺍﻝﻭﺼﻭل ﺍﻝﺒﻌﻴﺩ‪ .‬ﺒﺎﻻﺴﺘﻔﺎﺩﺓ ﻤـﻥ ﺨﻴـﺎﺭﺍﺕ‬ ‫ﺍﻝﺘﺸﻔﻴﺭ ﻭﻤﺼﺎﺩﻗﺔ ﺒﺭﻭﺘﻭﮑﻭل ﻨﻘﻁﺔ ﺇﻝﻰ ﻨﻘﻁﺔ ‪ ،PPP‬ﻭﺘﻌﺭﻴﻑ ﺘـﺼﻔﻴﺔ ‪ PPTP‬ﻋﻠـﻰ‬ ‫ﻤﻠﻘﻡ ﺍﻝﻭﺼﻭل ﺍﻝﺒﻌﻴﺩ ﺍﻝﺨﺎﺹ ﺒﻙ‪ ،‬ﻭﺘﻘﻴﻴﺩ ﻤﻠﻘﻡ ﺍﻝﻭﺼﻭل ﺍﻝﺒﻌﻴﺩ ﻋﻠﻰ ﺇﻨﺘﺭﻨﺕ ﻝﻴﻘﺒل ﻓﻘـﻁ‬ ‫ﻋﻤﻼﺀ ‪ PPTP‬ﺍﻝ ﺼﺎﺩﻕ ﻋﻠﻴﻬﻡ ﺍﻝﺫﻴﻥ ﻗﺎﻤﻭﺍ ﺒﺘﺸﻔﻴﺭ ﺍﻝﺒﻴﺎﻨﺎﺕ‪ ،‬ﻴﻤﮑﻥ ﻝﻤـﺴﺅﻭل ﺍﻝﻨﻅـﺎﻡ‬ ‫ﺘﺤﺴﻴﻥ ﺃﻤﺎﻥ ﺍﻝﺒﻴﺎﻨﺎﺕ ﻭﺇﺩﺍﺭﺓ ﺍﻝﻤﺴﺘﺨﺩﻤﻴﻥ ﺍﻝﺒﻌﻴﺩﻴﻥ ﺒﺸﮑل ﺃﮑﺜﺭ ﻓﻌﺎﻝﻴﺔ‪.‬‬ ‫ﻴﻭﺠﺩ ﻓﻲ ﺒﻌﺽ ﺍﻝﺒﻴﺌﺎﺕ ﺒﻴﺎﻨﺎﺕ ﻫﺎﻤﺔ ﺠﺩﹰﺍ ﺒﺤﻴﺙ ﻴﺠﺏ ﻋﺯﻝﻬﺎ‪ ،‬ﻭﺇﺨﻔﺎﺅﻫﺎ‪ ،‬ﺒﺸﮑل‬ ‫ﻓﻌﻠﻲ ﻋﻥ ﺃﻏﻠﺒﻴﺔ ﺍﻝﻤﺴﺘﺨﺩﻤﻴﻥ ﻓﻲ ﺍﻝﺸﺭﮑﺔ‪ .‬ﻤﺜل ﺍﻝﺒﻴﺎﻨﺎﺕ ﺍﻝﻤﺎﻝﻴـﺔ ﺃﻭ ﺒﻴﺎﻨـﺎﺕ ﺍﻝﻤـﻭﺍﺭﺩ‬ ‫ﺍﻝﺒﺸﺭﻴﺔ‪ .‬ﻭﺘﺴﺘﻌﻤل ﺍﻝﺸﺭﮑﺎﺕ ﺍﺘﺼﺎﻻﺕ ‪ VPN‬ﻋﺒﺭ ﻤﻠﻘﻡ ‪ VPN‬ﻝﻔﺭﺯ ﺍﻝﺒﻴﺎﻨﺎﺕ ﺒﺎﻝﻐـﺔ‬ ‫ﺍﻷﻫﻤﻴﺔ ﺒﺸﮑل ﻓﻌﻠﻲ‪ ،‬ﻤﻊ ﺍﻝﺴﻤﺎﺡ ﺒﺎﻝﻭﺼﻭل ﺍﻵﻤﻥ ﺇﻝﻴﻬﺎ ﻤﻥ ﻗﺒل ﻤﺴﺘﺨﺩﻤﻴﻥ ﻤﺨﺘـﺎﺭﻴﻥ‪.‬‬ ‫ﻴﺴﺘﻁﻴﻊ ﺍﻝﻤﺴﺘﺨﺩﻤﻭﻥ ﺍﻝﻤﻭﺠﻭﺩﻭﻥ ﻋﻠﻰ ﺸﺒﮑﺔ ﺍﻨﺘﺭﺍﻨﺕ ﻝﻠﺸﺭﮑﺔ ﻭﺍﻝﺫﻴﻥ ﻨﺤﻭﺍ ﺍﻷﺫﻭﻨﺎﺕ‬ ‫ﺍﻝﻤﻨﺎﺴﺒﺔ‪ ،‬ﺘﺄﺴﻴﺱ ﺍﺘﺼﺎل ﻋﻤﻴل ‪ VPN‬ﺒﻌﻴﺩ ﻤﻊ ﻤﻠﻘﻡ ‪ VPN‬ﻭﻴﺴﺘﻁﻴﻌﻭﻥ ﺍﻝﻭﺼﻭل ﺇﻝﻰ‬ ‫ﺍﻝﻤﻭﺍﺭﺩ ﺍﻝﻤﺤﻤﻴﺔ ﻋﻠﻰ ﺸﺒﮑﺔ ﺍﻝﻘﺴﻡ ﺍﻝﺤ ﺎﺱ‪ .‬ﺒﺎﻹﻀﺎﻓﺔ ﺇﻝﻰ ﺫﻝﻙ‪ ،‬ﺘﮑﻭﻥ ﮑﺎﻓﺔ ﺍﻻﺘﺼﺎﻻﺕ‬ ‫ﻋﺒﺭ ‪ VPN‬ﻤﺸﻔﺭﺓ ﻤﻥ ﺃﺠل ﺴﺭﻴﺔ ﺍﻝﺒﻴﺎﻨﺎﺕ‪ .‬ﻭﺍﻝﻤﺴﺘﺨﺩﻤﻭﻥ ﺍﻝﺫﻴﻥ ﻻ ﻴﻤﻠﮑﻭﻥ ﺍﻷﺫﻭﻨﺎﺕ‬ ‫ﺍﻝﻤﻨﺎﺴﺒﺔ ﻝﺘﺄﺴﻴﺱ ﺍﺘﺼﺎل ‪ VPN‬ﻤﻊ ﻤﻠﻘﻡ ‪ VPN‬ﻻ ﻴﺴﺘﻁﻴﻌﻭﻥ ﺭﺅﻴﺔ ﺍﻝﻤﻠﻘﻡ ﺍﻝﻤﺨﻔﻲ‪.‬‬ ‫ﻭﻗﺩ ﺤﻠﺕ ﺍﻝﺸﺒﮑﺔ ﺍﻝﻅﺎﻫﺭﻴﺔ ﻤﺸﮑﻠﺔ ﺘﮑﻠﻔﺔ ﺍﻻﺘﺼﺎل ﺍﻝﺒﻌﻴﺩ ﺒﻴﻥ ﺍﻝـﺸﺒﮑﺎﺕ ﺴـﻭﺍﺀ‬ ‫ﻓﺭﻭﻉ ﺍﻝﺸﺒﮑﺎﺕ ﻓﻲ ﺍﻷﻤﺎﮑﻥ ﺍﻝﺒﻌﻴﺩﺓ ﺃﻭ ﺍﻝﺸﺭﮑﺎﺀ ﺍﻝﻤﺨﺘﻠﻔﻴﻥ‪ ،‬ﻭﮑﺎﻨﺕ ﺍﻝﺘﮑﻠﻔﺔ ﺍﻝﮑﺒﻴﺭﺓ ﻝﺭﺒﻁ‬ ‫ﺸﺒﮑﺘﻴﻥ ﺒﻌﻴﺩﺘﻴﻥ ﻋﺎﺌﻕ ﺤﻘﻴﻘﻲ ﺃﻤﺎﻡ ﺒﻌﺽ ﺍﻝﺸﺭﮑﺎﺕ ﺍﻝﺘﻲ ﺘﺭﻏﺏ ﻓﻲ ﺘﻭﺴﻴﻊ ﺩﺍﺌﺭﺓ ﺍﻹﺩﺍﺭﺓ‬ ‫ﻭﺍﻝﺘﺤﮑﻡ ﻭﻨﻘل ﺍﻝﻤﻌﻁﻴﺎﺕ ﺒﻴﻥ ﻓﺭﻭﻋﻬﺎ‪.‬‬

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‫ري‬

‫‪Wireless Networks‬‬

‫ﻭﺠﺎﺀﺕ ﺍﻝﺸﺒﮑﺔ ﺍﻝﺨﺼﻭﺼﻴﺔ ﺍﻝﻭﻫﻤﻴﺔ ﻝﺘﺤل ﻫﺫﻩ ﺍﻝﻤﺸﮑﻠﺔ ﺒﺘﺨﻔﻴﺽ ﮑﺒﻴﺭ ﻓﻲ ﮑﻠﻔﺔ‬ ‫ﺍﻻﺘﺼﺎل ﺍﻝﺒﻌﻴﺩ‪.‬‬

‫ﻤﻤﻴﺯﺍﺕ ﺸﺒﮑﺔ ‪VPN‬‬ ‫ﺭﺨﻴﺼـﺔ‪:‬‬ ‫ﻴﻌﺘﺒﺭ ﺭﺨﺹ ﺍﻝﺘﮑﻠﻔﺔ ﻓﻲ ﺸﺒﮑﺔ ‪ VPN‬ﻫﻲ ﺍﻝﻤﻴﺯﺓ ﺍﻷﮑﺒﺭ ﻓﻴﻬﺎ ﻤﻊ ﻤﻘﺎﺭﻨﺔ ﺍﻻﺘـﺼﺎل‬ ‫ﺒﺎﺴﺘﺨﺩﺍﻡ ﻁﺭﻴﻘﺔ ﺃﺨﺭﻯ ﻤﺜل ﺩﺍﺭﺓ ﻁﻭﻴﻠﺔ ﻤﺅﺠﺭﺓ ﻓﺎﻝﺭﺒﻁ ﻴﮑـﻭﻥ ﺒﺎﻻﺘـﺼﺎل ﺒـﺎﻝﻤﺯﻭﺩ‬ ‫ﻻ ﺒـﺸﺒﮑﺔ‬ ‫ﺍﻝﻤﺤﻠﻲ ﻝﻺﻨﺘﺭﻨﺕ ﺜﻡ ﺘﻨﺸﺎﺀ ﺸﺒﮑﺔ ‪ VPN‬ﻝﻠﻤﻠﻘﻡ ﺍﻝﻬﺩﻑ ﺍﻝﺫﻱ ﻴﮑﻭﻥ ﻤﻭﺼـﻭ ﹰ‬ ‫ﺍﻹﻨﺘﺭﻨﺕ ﺒﺨﻁ ‪ DSL‬ﻤﻊ ﻋﻨﻭﺍﻥ ‪ IP‬ﺜﺎﺒﺕ ‪. ،،‬‬ ‫ﺁﻤﻨﺔ‪:‬‬ ‫ﻭﻫﻲ ﺸﺒﮑﺔ ﺁﻤﻨﺔ ﺤﻴﺙ ﺘﺴﺘﺨﺩﻡ ﻓﻲ ﺍﻻﺘﺼﺎل ﺍﺘﻔﺎﻗﻴﺎﺕ ﺍﻻﺘﺼﺎل ﺍﻵﻤـﻥ‪ ،‬ﻭﻴـﺩﻋﻡ‬ ‫ﻭﻴﻨﺩﻭﺯ ‪ 2000‬ﺍﺘﻔﺎﻗﻴﺘﻴﻥ ﻭﻫﻲ ‪ PPTP‬ﻨﻘﻁﺔ ﺇﻝﻰ ﻨﻘﻁﺔ‪ ،‬ﻭﺍﺘﻔﺎﻗﻴﺔ ‪ L2TP‬ﻭﻫﺫﻩ ﺍﻻﺘﻔﺎﻗﺎﺕ‬ ‫ﻫﻲ ﻋﺒﺎﺭﺓ ﻋﻥ ﺒﺭﻭﺘﻭﮑﻭﻻﺕ ﺁﻤﻨﺔ ﺘﻨﻘل ﺍﻝﻤﻌﻁﻴﺎﺕ ﻋﺒﺭ ﺍﻹﻨﺘﺭﻨﺕ ﻓﻲ ﺸـﺒﮑﺔ ‪، VPN‬‬ ‫ﻭﺍﻝﺒﺭﻭﺘﻭﮑﻭل ‪ L2TP‬ﻫﻭ ﺍﻷﻗﻭﻯ ﺤﻴﺙ ﺃﻨﻪ ﻴﻌﺘﺒﺭ ﺨﻠﻴﻁ ﻤـﻥ ﺍﻝﺒﺭﻭﺘﻭﮑـﻭل ‪ PPTP‬ﻭ‬ ‫‪L2F‬‬

‫ﻤـﻭﺜـﻭﻗـﺔ‪:‬‬ ‫ﻭﻫﻲ ﻤﻭﺜﻭﻗﺔ ﺤﻴﺙ ﻤﻥ ﻭﺍﻗﻊ ﺘﺠﺭﺒﺔ ﮑﺜﻴﺭ ﻤﻥ ﺍﻝﺸﺭﮑﺎﺕ ﻭﺍﻝﻘﻁﺎﻋﺎﺕ ﺤﺘﻰ ﺍﻝﺴﺭﻴﺔ ﻤﻨﻬـﺎ‬ ‫ﺘﻌﺘﺒﺭ ﺘﺠﺎﺭﺏ ﻨﺎﺠﺤﺔ ﻭﻫﻲ ﺴﻬﻠﺔ ﻓﻲ ﺇﻋﺩﺍﺩ ﺨﺎﺩﻡ ‪ VPN‬ﻭﺴﻬﻠﺔ ﻓﻲ ﻭﺼل ﻋﻤﻴل ﺍﻝﺸﺒﮑﺔ‬ ‫ﺴﻭﺍﺀ ﮑﺎﻥ ﻋﻤﻴل ﻭﻴﻨﺩﻭﺯ ‪ 2000‬ﺃﻭ ﻋﻤﻴل ‪ XP‬ﺃﻭ ﺤﺘﻰ ﻭﻴﻨﺩﻭﺯ ‪. x9‬‬ ‫ﺴـﻬﻠﺔ‪:‬‬ ‫ﺍﻝﺘﺠﻬﻴﺯ ﺤﺘﻰ ﺘﮑﻭﻥ ﻤﺴﺘﻌﺩ ﻝﻌﻤل ﺍﻝﺸﺒﮑﺔ ﻴﻠﺯﻡ ﺍﻝﺘﺄﮑﺩ ﻤﻥ ﻋﺩﺩ ﻤﻥ ﺍﻷﻤﻭﺭ ﻤﻨﻬﺎ‪:‬‬

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‫ري‬

‫‪Wireless Networks‬‬

‫• ﺨﺎﺩﻡ ﺍﻝـ ‪ VPN‬ﻴﮑﻭﻥ ﻤﻭﺼﻭل ﺒﺸﺒﮑﺔ ﺍﻹﻨﺘﺭﻨﺕ ﺒﺨﻁ ‪ DSL‬ﻤﻊ ﻋﻨـﻭﺍﻥ ‪IP‬‬ ‫ﺜﺎﺒﺕ‪.‬‬ ‫• ﺨﺎﺩﻡ ﺍﻝـ ‪ VPN‬ﻴﮑﻭﻥ ﻤﺜﺒﺕ ﻋﻠﻴﻪ ﺃﻭ ﻋﻠﻰ ﺨﺎﺩﻡ ﺜﺎﻨﻲ ﻓﻲ ﻨﻔﺱ ﺍﻝﺸﺒﮑﺔ ﺨﺩﻤـﺔ‬ ‫‪DHCP‬‬ ‫• ﻋﻤﻼﺀ ﺍﻝﻭﺼﻭل ﺍﻝﺒﻌﻴﺩ ﻝﻬﻡ ﺤﺴﺎﺏ ﻓﻲ ﺍﻝﺸﺒﮑﺔ ﺒﺎﺴﻡ ﻭﮑﻠﻤﺔ ﻤﺭﻭﺭ‪.‬‬ ‫• ﺃﺠﻬﺯﺓ ﺍﻝﻌﻤﻼﺀ ﻗﺎﺩﺭﺓ ﻋﻠﻰ ﺘﺄﺴﻴﺱ ﺍﻻﺘﺼﺎل ﺒﺘﺩﺭﻴﺏ ﺃﺼﺤﺎﺒﻬﺎ ﺃﻭ ﺘﻘﻭﻡ ﺒﺘﺠﻬﻴﺯﻫﺎ‬ ‫ﺃﻨﺕ‪.‬‬ ‫ﺘﺘﻠﺨﺹ ﺍﻝﻔﮑﺭﺓ ﻓﻲ ﺍﺴﺘﺨﺩﺍﻡ ﺸﺒﮑﺔ ﺍﻹﻨﺘﺭﻨﺕ ﻝﺘﻤﮑﻴﻥ ﺭﺠـﺎل ﺍﻷﻋﻤـﺎل ﻭ ﮑﺒـﺎﺭ‬ ‫ﺍﻝﻤﻭﻅﻔﻴﻥ ﺃﻭ ﺃﻱ ﺸﺨﺹ ﻤﺼﺭﺡ ﻝﻪ ﺒﺫﻝﻙ ﻤﻥ ﺍﻝﺩﺨﻭل ﺇﻝﻰ ﺍﻝﺸﺒﮑﺔ ﺍﻝﻤﺤﻠﻴﺔ ﺍﻝﺨﺎﺼﺔ ﺒﻤﻘﺭ‬ ‫ﺍﻝﻌﻤل ﻝﻠﺩﺨﻭل ﺇﻝﻰ ﺠﻤﻴﻊ ﺍﻝﺒﺭﺍﻤﺞ ﻭ ﺍﻝﻤﻌﻠﻭﻤﺎﺕ ﻭ ﻷﺩﺍﺀ ﻭ ﺘﻨﻔﻴﺫ ﺒﻌﺽ ﺍﻝﻤﻬـﺎﻡ ﺃﺜﻨـﺎﺀ‬ ‫ﺘﻭﺍﺠﺩﻫﻡ ﺨﺎﺭﺝ ﺍﻝﻤﮑﺘﺏ ﺃﻭ ﺃﺜﻨﺎﺀ ﺍﻝﺴﻔﺭ ﺒﻌﻴﺩﺍ ﻋﻥ ﻤﻘﺭ ﺍﻝﻌﻤل‪.‬‬ ‫ﮑﻴﻔﻴﺔ ﻋﻤﻠﻬﺎ‬ ‫ﻴﺘﻡ ﺇﺭﺴﺎل ﻭﺍﺴﺘﻘﺒﺎل ﺍﻝﻤﻌﻠﻭﻤﺎﺕ ﻋﻠﻰ ﺸﮑل ﺠﻴﻭﺏ ﺼﻐﻴﺭﺓ ﻤـﻥ ﺍﻝﻤﻌﻠﻭﻤـﺎﺕ‪،‬‬ ‫ﺒﺤﻴﺙ ﻴﺘﻡ ﺘﻘﺴﻴﻡ ﺍﻝﻤﻌﻠﻭﻤﺎﺕ ﺇﻝﻰ ﻫﺫﻩ ﺍﻝﺠﻴﻭﺏ ﺍﻝﺼﻐﻴﺭﺓ ﻝﺘﺴﻬل ﻤﻥ ﻋﻤﻠﻴﺔ ﻨﻘﻠﻬـﺎ ﻋﻠـﻰ‬ ‫ﺸﺒﮑﺔ ﺍﻹﻨﺘﺭﻨﺕ ﻭﮑل ﺠﻴﺏ ﻴﺤﻤل ﻋﻨﻭﺍﻥ ﺍﻝﻤﺭﺴل ﻭﺍﻝﻤﺴﺘﻘﺒل ﻭﮑﺫﻝﻙ ﺒﻁﺎﻗﺔ ﻤﻤﻴﺯﺓ ﺘﺴﺎﻋﺩ‬ ‫ﻋﻠﻰ ﺘﻭﺠﻴﻪ ﺍﻝﺠﻴﺏ ﻋﻨﺩ ﺍﻝﻭﺼﻭل ﺇﻝﻰ ﺠﻬﺎﺯ ﺍﻝﻤﺴﺘﻘﺒل ﻨﻅﺭﹰﺍ ﻝﻠﻤﺨﺎﻁﺭ ﺍﻝﻤﻭﺠﻭﺩﺓ ﻋﻠـﻰ‬ ‫ﺸﺒﮑﺔ ﺍﻹﻨﺘﺭﻨﺕ ﻓﺈﻥ ﺠﻤﻴﻊ ﺍﻝﺠﻴﻭﺏ ﻴﺘﻡ ﺘﺸﻔﻴﺭﻫﺎ ﻭﻴﺘﻡ ﺇﻀﺎﻓﺔ ﺍﻝﺘﻭﻗﻴﻊ ﺍﻹﻝﮑﺘﺭﻭﻨﻲ ﻝﻠﻤﺭﺴل‬ ‫ﻝﻴﺘﻡ ﺍﻝﺘﺄﮑﺩ ﻤﻥ ﻫﻭﻴﺘﻪ ﻭﻴﺘﻡ ﺘﻐﻠﻴﻑ ﻫﺫﻩ ﺍﻝﺠﻴﻭﺏ ﺍﻝﻤﺸﻔﺭﺓ ﺒﻌﺩ ﺫﻝﻙ ﺒﻐﻼﻑ ﺨـﺎﺭﺠﻲ ﻭﻻ‬ ‫ﻴﻅﻬﺭ ﻤﻥ ﺍﻝﻤﻌﻠﻭﻤﺎﺕ ﺴﻭﻯ ﻋﻨﻭﺍﻥ ﺍﻝﻤﺭﺴل ﺇﻝﻴﻪ ﻭ ﺘﺴﻤﻰ ﻫﺫﻩ ﺍﻝﻌﻤﻠﻴﺔ ﺒﺈﻨﺸﺎﺀ ﺍﻷﻨﺒـﻭﺏ‬ ‫‪.Tunneling‬‬ ‫ﺒﻌﺩ ﻭﺼﻭل ﺍﻝﺠﻴﻭﺏ ﺇﻝﻰ ﺍﻝﺠﻬﺎﺯ ﺍﻝﻤﺴﺘﻘﺒل ﻴﺘﻡ ﺍﻝﺘﺄﮑﺩ ﻤﻥ ﺃﻨﻬﺎ ﻤﻥ ﻁﺭﻑ ﺸﺨﺹ‬ ‫ﻤﺨﻭل ﻝﻪ ﺒﺎﺴﺘﺨﺩﺍﻡ ﺍﻝﺸﺒﮑﺔ ﺍﻻﻓﺘﺭﺍﻀﻴﺔ ﻭﻴﺘﻡ ﻓﻙ ﺍﻝﺸﻔﺭﺓ ﻭﻴﺘﻡ ﺘﺠﻤﻴﻊ ﺍﻝﻤﻌﻠﻭﻤﺎﺕ ﻭﺘﺭﺘﻴﺒﻬﺎ‬ ‫ﻤﺭﺓ ﺃﺨﺭﻯ ﻭﺇﺭﺴﺎﻝﻬﺎ ﺇﻝﻰ ﺍﻝﺸﺨﺹ ﺃﻭ ﺍﻝﺠﻬﺎﺯ ﺍﻝﻤﺭﺴل ﺇﻝﻴﻪ ﺩﺍﺨل ﺍﻝﺸﺒﮑﺔ ﺍﻝﻤﺤﻠﻴﺔ‪.‬‬

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‫ھ نا‬

‫ري‬

‫‪Wireless Networks‬‬

‫ﺘﺠﻬﻴﺯ ﺸﺒﮑﺔ ‪:VPN‬‬ ‫ﻝﺘﺠﻬﻴﺯ ﺍﻝﺨﺎﺩﻡ ﻝﻘﺒﻭل ﺍﺘﺼﺎﻻﺕ ‪ VPN‬ﻨﺤﺘﺎﺝ ﺇﻝﻰ ﺘﺜﺒﻴﺕ ﺍﻝﺨﺩﻤﺔ ‪ RRAS‬ﻭﻫـﻲ‬ ‫ﺘﮑﻭﻥ ﻤﺜﺒﺘﻪ ﻤﻊ ﺘﺜﺒﻴﺕ ﺍﻝﻭﻴﻨﺩﻭﺯ ‪ 2000‬ﻭﻝﮑﻥ ﺘﮑﻭﻥ ﻏﻴﺭ ﻤﻤﮑﻨﺔ ﻭﺘﺤﺘﺎﺝ ﺇﻝـﻰ ﺘﻔﻌﻴ‪،‬ﻝـ‬ ‫ﻭﺴﻨﻘﻭﻡ ﺒﺘﻤﮑﻴﻥ ﺍﻝﺨﺩﻤﺔ ﻋﻠﻰ ﻤﻠﻘﻡ ﻭﻴﻨﺩﻭﺯ ‪ ،2000‬ﻭﻝﮑﻥ ﻨﻔﺘﺭﺽ ﻓﻲ ﻫﺫﺍ ﺍﻝﺸﺭﺡ ﻭﺠﻭﺩ‬ ‫ﺨﺩﻤﺔ ﺍﻝـ ‪ DHCP‬ﻋﻠﻰ ﻨﻔﺱ ﺍﻝﺨﺎﺩﻡ‪ ،‬ﻤﻊ ﺍﺘﺼﺎل ﺩﺍﺌﻡ ﺒﺎﻹﻨﺘﺭﻨﺕ ﻤﻊ ﻤﻌﺭﻓﺘﻙ ﺒﻌﻨـﻭﺍﻥ‬ ‫‪ IP‬ﺍﻝﺜﺎﺒﺕ‪ ،‬ﺴﻨﻘﻭﻡ ﻓﻲ ﻤﺜﺎﻝﻨﺎ ﻫﺫﺍ ﺒﺈﻋﺩﺍﺩ ﻤﺨﺩﻡ ‪ ، VPN PPTP‬ﻷﻥ ﻫﺫﺍ ﺍﻝﻤﺨﺩﻡ ﻴﻌﺘﺒﺭ‬ ‫ﺍﺴﻬل ﻓﻲ ﺍﻹﻋﺩﺍﺩ ﻭﺍﻝﻭﺼﻭل ﺇﻝﻴﻪ ﺒﺴﺒﺏ ﺍﺴﺘﺨﺩﺍﻤﻪ ﻝﻭﺜﺎﺌﻕ ‪ Logon‬ﻝﻠﻤﺴﺘﺜﻤﺭ ﻓﻘﻁ‪ ،‬ﺃﻤـﺎ‬ ‫ﻤﺨﺩﻡ ‪ VPN L2TP‬ﻓﻬﻭ ﻴﺴﺘﺨﺩﻡ ﻓﻲ ﮑﺜﻴﺭ ﻤﻥ ﺍﻝﺤﺎﻻﺕ ﺒﻴﻥ ﺍﻝﻤﺨﺩﻤﺎﺕ ﻝﻤﺎ ﻝـﻪ ﻤـﻥ‬ ‫ﻤﺯﺍﻴﺎ ﻓﻲ ﺍﻷﻤﻥ ﺍﮑﺒﺭ‪ .‬ﺍﺨﺘﺭ‬ ‫‪Programs < Administrative Tools < Routing and Remote Access‬‬

‫ﺜﻡ ﻤﻥ ﻋﻠﻰ ﺍﺴﻡ ﺍﻝﺨﺎﺩﻡ ﺒﺎﻝﺯﺭ ﺍﻷﻴﻤﻥ ﺍﺨﺘﺭ‬ ‫‪Configure And Enable Routing And Remote Access‬‬

‫ﻴﻔﺘﺢ ﻝﻙ ﻤﻌﺎﻝﺞ ﺍﻝﺘﺜﺒﻴﺕ ﺍﻨﻘﺭ ‪ Next‬ﻤﻥ ﻫﺫﻩ ﺍﻝﻨﺎﻓﺫﺓ ﺍﺨﺘﺭ ﺍﻝﺨﻴﺎﺭ ﺸﺒﮑﺔ ‪VPN‬‬ ‫ﻓﻲ ﺍﻝﻨﺎﻓﺫﺓ ﺍﻝﺘﺎﻝﻴﺔ ﺘﺄﮑﺩ ﻤﻥ ﻭﺠﻭﺩ ﺍﻝﺒﺭﻭﺘﻭﮑﻭل ‪ TCP/IP‬ﻭﺍﺘﺭﻙ ﺍﻝﺨﻴﺎﺭ ﺍﻝﻤﺨﺘـﺎﺭ‬ ‫ﮑﻤﺎ ﻫﻭ ﺜﻡ ‪ Next‬ﺴﺘﺸﺎﻫﺩ ﺍﻵﻥ ﺍﺘﺼﺎﻻﺕ ﺍﻝﺨﺎﺩﻡ ﻭﻤﻨﻬﺎ ﺍﺘﺼﺎل ﺍﻹﻨﺘﺭﻨﺕ ﺍﺨﺘﺭ ﺍﻻﺘﺼﺎل‬ ‫ﺍﻝﺩﺍﺌﻡ ﺜﻡ ‪ Next‬ﻓﻲ ﻫﺫﻩ ﺍﻝﻨﺎﻓﺫﺓ ﺘﺨﺘﺎﺭ ﺃﻤﺎ ﺇﺴﻨﺎﺩ ﻋﻨﺎﻭﻴﻥ ﻤﺤـﺩﺩﺓ ﻝﻠﻌﻤـﻼﺀ ﺃﻭ ﺇﺴـﻨﺎﺩ‬ ‫ﺍﻝﻌﻨﺎﻭﻴﻥ ﻤﻥ ‪ DHCP‬ﺍﻗﺒل ﺍﻝﺨﻴﺎﺭ ‪ Automatically‬ﻝﻘﺒﻭل ﺍﺴﺘﺨﺩﺍﻡ ‪ DHCP‬ﺍﻝﻤﺤﻠﻲ‬ ‫ﻝﻠﻌﻤﻼﺀ ﺍﻝﻤﺘﺼﻠﻴﻥ‪.‬‬ ‫ﻤﻥ ﺃﺨﺭ ﻨﺎﻓﺫﺓ ﺍﺨﺘﺭ ﺍﻝﺨﻴﺎﺭ ﺍﻝﺘﻠﻘﺎﺌﻲ ﻓﻴﻬﺎ ﻭﻫﻲ ﻋﺩﻡ ﺍﺴﺘﺨﺩﺍﻡ ﺍﻝﺨﺩﻤـﺔ ‪RADIUS‬‬ ‫ﻝﺘﺤﻘﻕ ﻤﻥ ﺼﺤﺔ ﺍﻝﻤﻌﻠﻭﻤﺎﺕ ﺍﻝﻤﻘﺩﻤﺔ ﻤﻥ ﺍﻝﻤﺘﺼﻠﻴﻥ ‪ ،‬ﻻﻥ ﺘﻭﺜﻴﻕ ﺍﻝﻭﻴﻨﺩﻭﺯ ﺍﻝﺘﻠﻘﺎﺌﻲ ﻴﻔﻲ‬ ‫ﺒﮑل ﻤﺘﻁﻠﺒﺎﺘﻙ ﺍﻷﻤﻨﻴﺔ ﻋﻨﺩﻤﺎ ﺘﮑﻭﻥ ﺘﻤﻠﻙ ﺨﺎﺩﻡ ‪ RAS‬ﻭﺤﻴﺩ ﻋﻠﻰ ﺍﻝﺸﺒﮑﺔ ﺍﻨﻘـﺭ ‪Next‬‬

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‫ھ نا‬

‫ري‬

‫‪Wireless Networks‬‬

‫ﻓﺘﻅﻬﺭ ﻝﻙ ﺭﺴﺎﻝﺔ ﺘﺤﺫﻴﺭ ﻤﻥ ‪ DHCP‬ﻭﻫﻲ ﻏﻴﺭ ﻀﺭﻭﺭﻴﺔ ﺇﻻ ﻓﻲ ﺤﺎﻝﺔ ﻭﺠﻭﺩ ﻤﺨـﺩﻡ‬ ‫‪ DHCP‬ﻋﻠﻰ ﺸﺒﮑﺔ ﻓﺭﻋﻴﺔ ﺃﺨﺭﻯ ﺍﻨﻘﺭ ‪ OK‬ﺘﻅﻬﺭ ﻝﻙ ﻨﺎﻓﺫﺓ ﺍﻝﺘﺠﻬﻴﺯ ﻝﻌﻤل ﺍﻝﺨﺩﻤﺔ‪.‬‬ ‫ﺍﻵﻥ ﺘﺸﺎﻫﺩ ﺍﻝﻌﻼﻤﺔ ﺍﻝﺤﻤﺭﺍﺀ ﺍﻝﺘﻲ ﮑﺎﻨﺕ ﻋﻠﻰ ﺍﺴﻡ ﺍﻝﺨﺎﺩﻡ ﺃﺼﺒﺤﺕ ﺒﻠﻭﻥ ﺍﺨـﻀﺭ‪،‬‬ ‫ﻭﺒﻬﺫﺍ ﺘﮑﻭﻥ ﻗﺩ ﻤﮑﻨﺕ ﺍﻝﻤﻠﻘﻡ ﻤﻥ ﺍﻻﺴﺘﻌﺩﺍﺩ ﻻﺴﺘﻘﺒﺎل ﺍﻝﻌﻤﻼﺀ ﻋﺒـﺭ ﺒﻭﺍﺒـﺔ ﺍﻹﻨﺘﺭﻨـﺕ‪،‬‬ ‫ﻭﻁﺒﻌ ﹰﺎ ﻤﻊ ﻫﺫﺍ ﺍﻝﺘﺜﺒﻴﺕ ﺍﻻﻓﺘﺭﺍﻀﻲ ﺘﻭﺠﺩ ﺒﻌﺽ ﺍﻝﺨﺼﺎﺌﺹ ﺍﻝﺘﻲ ﻤﻥ ﺍﻝﻤﻤﮑـﻥ ﺘﻐﻴﺭﻫـﺎ‬ ‫ﺤﺴﺏ ﺤﺎﺠﺘﻙ ﻤﺜل ﻋﺩﺩ ﺍﻝﻤﻨﺎﻓﺫ ﻝﮑل ﺒﺭﻭﺘﻭﮑﻭل ﻭﻝﮑل ﺒﺭﻭﺘﻭﮑﻭل ﻋﻨﺩ ﺍﻝﺘﺜﺒﻴﺕ ﻋﺩﺩ ‪128‬‬ ‫ﻤﻨﻔﺫ ﻴﻤﮑﻥ ﺘﺨﻔﻴﺽ ﻤﻨﺎﻓﺫ ﺍﻝﺒﺭﻭﺘﻭﮑﻭل ‪ PPTP‬ﺇﻝﻰ ‪ 1‬ﻤﻨﻔﺫ ﻭﻝﮑﻥ ﻫﺫﺍ ﻋﺩﺩ ﻗﻠﻴل ﺠﺩﹰﺍ ﺤﺩﺩ‬ ‫ﻋﺩﺩ ﻤﻌﻘﻭ‪،‬ل ﻭﺍﻝﺒﺭﻭﺘﻭﮑﻭل ‪ L2TP‬ﻴﻤﮑﻥ ﺃﻥ ﺘﺤﺩﺩ ﺍﻝﺭﻗﻡ ‪ 0‬ﻴﻌﻨﻲ ﻻ ﻴﻭﺠﺩ ﻤﻨﻔﺫ‪ ،‬ﻝﺘﺤﺩﻴﺩ‬ ‫ﺃﻭ ﺇﻝﻐﺎﺀ ﺍﻝﻤﻨﺎﻓﺫ ﻤﻥ ﻋﻼﻤﺔ ‪ +‬ﺒﺠﺎﻨﺏ ﺍﺴﻡ ﺨﺎﺩﻡ ‪ VPN‬ﺘﻅﻬﺭ ﻝﻙ ‪ Ports‬ﺒﺎﻝﺯﺭ ﺍﻷﻴﻤﻥ‬ ‫ﻝﻠﻤﺎﻭﺱ ﻨﺨﺘﺎﺭ ﺨﺼﺎﺌﺹ ﺜﻡ ﻤﻥ ﺍﻝﻨﺎﻓﺫﺓ ﻨﺨﺘﺎﺭ ﺃﺤـﺩ‬

‫ﺜـﻡ ﻤـﻥ ﺍﻝـﺯﺭ‬ ‫ﺍﻝﺒﺭﻭﺘﻭﮑـﻭﻝﻴﻥ‬

‫‪ Configure‬ﺜﻡ ﺃﻤﺎﻡ ‪ Maximum ports‬ﺍﮑﺘﺏ ﺍﻝﺭﻗﻡ ﺍﻝﻤﻁﻠﻭﺏ‪.‬‬ ‫ﻭﻝﻠﺘﻭﺴﻊ ﺃﮑﺜﺭ ﻓﻲ ﻫﺫﺍ ﺍﻝﻤﺠﺎل ﻴﻤﮑﻨﻙ ﺍﻝﺭﺠﻭﻉ ﺇﻝﻰ ﻤﻭﻗﻊ ﺸﺭﮑﺔ ‪Microsoft‬‬ ‫ﻤﻭﻗﻊ ﺠﻴﺩ ﮑﻤﺭﺠﻊ‪:‬‬ ‫‪http://www.windowsnetworking.com‬‬ ‫ﺨﻁﻭﺍﺕ ﺍﻝﺘﻁﺒﻴﻕ ﻭﺍﻝﻤﺭﺍﺤل‪:‬‬ ‫‪ .1‬ﺃﻭل ﻤﺎ ﺘﺤﺘﺎﺠﻪ ﻫﻭ ﻨﻅﺎﻡ ﺘﺸﻐﻴل ﻴﺩﻋﻡ ﻫﺫﻩ ﺍﻝﺸﺒﮑﺔ‬ ‫‪ .2‬ﺍﻝﺤﺼﻭل ﻋﻠﻰ ﻨﻅﺎﻡ ﺘﺸﻐﻴل ﻴﺩﻋﻡ ﺍﻝﺸﺒﮑﺔ ﺍﻻﻓﺘﺭﺍﻀﻴﺔ ﻤﺜل ﻭﻴﻨﺩﻭﺯ ‪ Xp‬ﺤﻴﺙ ﺍﻨﻪ‬ ‫ﻴﺩﻋﻡ ﺍﻝﺸﺒﮑﺔ ﺍﻻﻓﺘﺭﺍﻀﻴﺔ‪.‬‬ ‫‪ .3‬ﻴﺠﺏ ﺃﻥ ﺘﻤﻠﻙ ﺭﻗﻡ ﺃﻱ ﺒﻲ ﺨﺎﺹ ﺒﻙ ﺃﻭ ﺍﺴﻡ ﻨﻁﺎﻕ‪.‬‬ ‫ﻹﻨﺸﺎﺀ ﺸﺒﮑﺔ ‪ VPN‬ﻨﻘﻭﻡ ﺒﺎﻝﺨﻁﻭﺍﺕ ﺍﻝﺘﺎﻝﻴﺔ ‪:‬‬ ‫‪ 1‬ـ ﺍﻝﺩﺨﻭل ﺇﻝﻰ ﻝﻭﺤﺔ ﺍﻝﺘﺤﮑﻡ ﻭﺍﺨﺘﻴﺎﺭ ﺍﺘﺼﺎﻻﺕ ﺸﺒﮑﺔ ﺍﻻﺘﺼﺎل ﻭﺍﻹﻨﺘﺭﻨﺕ ﻨﺨﺘـﺎﺭ‬ ‫ﻤﻥ ﻫﺫﻩ ﺍﻝﻘﺎﺌﻤﺔ ﺇﻨﺸﺎﺀ ﺍﺘﺼﺎل ﻓﻲ ﻤﮑﺎﻥ ﺍﻝﻌﻤل ﻓﺘﻅﻬﺭ ﻝﻨﺎ ﻗﺎﺌﻤﺔ ﻤﻌﺎﻝﺞ ﺍﺘﺼﺎل ﺠﺩﻴﺩ‪.‬‬

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‫‪Wireless Networks‬‬

‫ﻨﺨﺘﺎﺭ ﺍﻝﺒﻨﺩ ﺍﻝﺜﺎﻨﻲ ﺍﺘﺼﺎل ﺸﺒﮑﺔ ﺨﺎﺼﺔ ﻅﺎﻫﺭﻴﺔ ‪ VPN‬ﻭﻨﻀﻐﻁ ﺍﻝﺘﺎﻝﻲ ﻓﺘﻅﻬﺭ ﻝﻨﺎ ﻗﺎﺌﻤﺔ‬ ‫ﺘﻁﻠﺏ ﺇﺩﺨﺎل ﺍﺴﻡ ﺍﻝﺸﺭﮑﺔ ﺃﻭ ﺍﻻﺴﻡ ﺍﻝﺫﻱ ﻨﺭﻴﺩ ﺘﺴﻤﻴﺔ ﺍﻻﺘﺼﺎل ﺒﻪ‪.‬‬ ‫ﺇﺩﺨﺎل ﺃﻱ ﺍﺴﻡ ﻨﺭﻴﺩﻩ ﺃﻭ ﺍﺴﻡ ﻤﻠﻘﻡ ﻤﺜﻼ‪ ،‬ﻋﻨﺩ ﺍﻝﻀﻐﻁ ﻋﻠﻰ ﺍﻝﺘﺎﻝﻲ ﺴـﺘﻅﻬﺭ ﻝﺘـﺎ‬ ‫ﻴﻤﮑﻥ‬ ‫ﺍﻝﻼﺌﺤﺔ ﺍﻝﺘﺎﻝﻴﺔ‪:‬‬

‫ﻤﻥ ﻫﻨﺎ ﻴﺘﻴﺢ ﻝﻨﺎ ﻨﻅﺎﻡ ﺍﻝﺘﺸﻐﻴل ﺇﻤﮑﺎﻨﻴﺔ ﺍﺨﺘﻴﺎﺭ ﻁﻠﺏ ﺍﻻﺘﺼﺎل ﺍﻷﻭﻝﻲ ﺇﻝﻰ ﺍﻹﻨﺘﺭﻨـﺕ ﺃﻭ‬ ‫ﺇﻝﻰ ﺸﺒﮑﺔ ﺍﻻﺘﺼﺎل ﻓﻲ ﺤﺎل ﮑﺎﻥ ﺍﻝﺠﻬﺎﺯ ﺍﻝﺫﻱ ﻨﺴﺘﺨﺩﻤﻪ ﻤﻭﺼـﻭل ﺇﻝـﻰ ﺸـﺒﮑﺔ‪،‬ﻋﻨﺩ‬ ‫‪33‬‬ ‫تو ا‬

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‫‪Wireless Networks‬‬

‫ﺍﻻﻨﺘﻘﺎل ﺇﻝﻰ ﺍﻝﻤﺭﺤﻠﺔ ﺍﻝﺘﺎﻝﻴﺔ ﻴﻁﻠﺏ ﻤﻌﺎﻝﺞ ﺍﺘﺼﺎل ﺠﺩﻴﺩ ﻤﻥ ﺍﻝﻤـﺴﺘﺨﺩﻡ ﺇﺩﺨـﺎل ﺍﺴـﻡ‬ ‫ﺍﻝﻤﻀﻴﻑ ﺃﻭ ﻋﻨﻭﺍﻥ ﺒﺭﻭﺘﻭﮑﻭل ﺇﻨﺘﺭﻨﺕ ﻝﺠﻬﺎﺯ ﺍﻝﮑﻤﺒﻴﻭﺘﺭ ﺍﻝﺫﻱ ﻨﺘﺼل ﺒﻪ‬ ‫ﻭ ﻫﻨﺎ ﻴﺠﺏ ﺍﻻﻨﺘﺒﺎﻩ ﺇﻝﻰ ﻋﻨـﻭﺍﻥ‬ ‫‪ IP‬ﺍﻝﺫﻱ ﻴﺠﺏ ﺇﺩﺨﺎﻝﻪ ‪,‬ﻴﺠﺏ ﺃﻥ‬ ‫ﻴﮑﻭﻥ ﻋﻨﻭﺍﻥ ‪IP‬‬ ‫ﺍﻹﻨﺘﺭﻨـﺕ ﻝﻠﺠﻬـﺎﺯ ﺍﻝﻤـﻀﻴﻑ‬ ‫ﻭﻝﻴﺱ ﻋﻨﻭﺍﻥ ﺍﻝﺸﺒﮑﺔ ﻓﻲ ﺤـﺎل‬ ‫ﮑﺎﻥ ﺍﻝﺠﻬﺎﺯ ﻤﻭﺼﻭل ﺇﻝﻰ ﺸﺒﮑﺔ‪.‬‬ ‫ﻭﻝﮑﻥ ﮑﻴﻑ ﻨﺤـﺼل ﻋﻠـﻰ ‪IP‬‬ ‫ﺍﻹﻨﺘﺭﻨﺕ ﺍﻝﺫﻱ ﻨﺭﻴﺩﻩ ؟‬ ‫ﺇﺫﺍ ﮑﺎﻥ ﺍﻝﺠﻬﺎﺯ ﻤﺘﺼل ﻋﻠﻰ ﺍﻹﻨﺘﺭﻨﺕ ﻴﻭﺠﺩ ﻤﻭﺍﻗﻊ ﺘﻌﻁﻴﻨﺎ ‪ IP‬ﻝﻠﺠﻬﺎﺯ ﺍﻝﺫﻱ ﻨـﺴﺘﺨﺩﻤﻪ‬ ‫‪,‬ﺃﻭ ﻨﺤﺼل ﻋﻠﻴﻪ ﻤﻥ ‪ MS-DOS‬ﻭﻫﻨﺎ ﺃﻭﺩ ﺍﻝﺘﻨﻭﻴﻪ ﺇﻝﻰ ﺃﻫﻤﻴﺔ ‪ MS-DOS‬ﻭﺍﻝﺤﺎﺠـﺔ‬ ‫ﺇﻝﻴﻪ ﻤﻊ ﺃﻱ ﻨﻅﺎﻡ ﺘﺸﻐﻴل ﻤﻥ ﺇﺼﺩﺍﺭﺍﺕ ﻭﻴﻨﺩﻭﺯ ﺍﻝﻤﺨﺘﻠﻔﺔ ‪.‬‬ ‫ﻨﺩﺨل ﺇﻝﻰ‬

‫‪ MS-DOS‬ﻭ ﻨﮑﺘﺏ ﺍﻷﻤﺭ ﺍﻝﺘﺎﻝﻲ ‪ IPCONFIG‬ﺴﻴﻌﻁﻴﻨﺎ ‪ IP‬ﺍﻹﻨﺘﺭﻨـﺕ‬

‫ﻭﺍﻝﺸﺒﮑﺔ ﻓﻲ ﺤﺎل ﻭﺠﻭﺩﻫﺎ‪.‬‬

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‫‪Wireless Networks‬‬

‫ﺒﻌﺩ ﺍﻝﺘﺄﮑﺩ ﻤﻥ ﺇﺩﺨﺎل ﺍﻝـ ‪ IP‬ﻨﻀﻐﻁ ﺍﻝﺘﺎﻝﻲ ﻓﻅﻬﺭ ﺍﻝﻘﺎﺌﻤﺔ ﺍﻝﺘﺎﻝﻴﺔ ﻭﺍﻝﺘﻲ ﺘﺸﻴﺭ ﺇﻝﻰ ﻨﻬﺎﻴﺔ‬ ‫ﻋﻤل ﻤﻌﺎﻝﺞ ﺍﺘﺼﺎل ﺠﺩﻴﺩ ﻭﺘﻌﻁﻴﻨﺎ ﺇﻤﮑﺎﻨﻴﺔ ﺇﻀﺎﻓﺔ ﺍﺨﺘﺼﺎﺭ ﻝﻠﺸﺒﮑﺔ ﺇﻝﻰ ﺴﻁﺢ ﺍﻝﻤﮑﺘﺏ ﻤﻊ‬ ‫ﻤﻼﺤﻅﺔ ﺃﻥ ﺍﻻﺨﺘﺼﺎﺭ ﻴﮑﻭﻥ ﺸﻔﺎﻑ ﺇﻝﻰ ﺃﻥ‬ ‫ﻴﺘﻡ ﺘﻔﻌﻴل ﺍﻻﺘﺼﺎل ‪.‬‬ ‫ﻋﻨﺩ ﺍﻝﻀﻐﻁ ﻋﻠﻰ ﺍﻻﺨﺘﺼﺎﺭ ﺍﻝﻤﻭﺠﻭﺩ ﻋﻠﻰ‬ ‫ﺴﻁﺢ ﺍﻝﻤﮑﺘﺏ ﺴﺘﻅﻬﺭ ﻝﺘﺎ ﻗﺎﺌﻤﺔ ﺘﺘﻁﻠﺏ ﺍﺴﻡ‬ ‫ﺍﻝﻤﺴﺘﺨﺩﻡ ﻭﮑﻠﻤﺔ ﺍﻝﻤـﺭﻭﺭ ﻝﻠـﺩﺨﻭل ﺇﻝـﻰ‬ ‫ﺍﻹﻨﺘﺭﻨﺕ ﻭﺍﺘﻤﺎﻡ ﺍﻻﺘﺼﺎل ﺒﻴﻥ ﺍﻝﺠﻬﺎﺯﻴﻥ‪.‬‬

‫ﻫل ﻴﻤﮑﻨﻙ ﺍﻝﺤﺼﻭل ﻋﻠﻰ ‪ IP‬ﺩﺍﺌﻡ؟؟؟!!!‬ ‫ﻫﺫﻩ ﺍﻝﺨﻁﻭﺓ ﻤﻬﻤﺔ ﺠﺩﹰﺍ ﻓﻔﻲ ﺤﺎل ﻭﺠﻭﺩ‬ ‫ﺃﻱ ﺨﻁﺄ ﻓﻲ ﺍﻝﻤﺭﺍﺤل ﺍﻝﺴﺎﺒﻘﺔ ﺃﻭ ﺇﺩﺨﺎل‬ ‫ﺨﺎﻁﺊ ﻝﻠﻌﻨﻭﺍﻥ ﻝﻥ ﺘﺘﻡ ﻋﻤﻠﻴﺔ ﺍﻝﺘﻭﺼﻴل‬ ‫ﺒﻴﻥ ﺍﻝﺠﻬﺎﺯﻴﻥ ﻭﺴﻴﮑﻭﻥ ﻋﻠﻴﻨـﺎ ﺇﻋـﺎﺩﺓ‬ ‫ﺍﻝﺨﻁﻭﺍﺕ ﺍﻝﺴﺎﺒﻘﺔ ﻤﻥ ﺠﺩﻴﺩ ‪ .‬ﻭﻓﻲ ﺤﺎل‬ ‫ﻋﺩﻡ ﻭﺠﻭﺩ ﺃﺨﻁﺎﺀ ﺃﻭ ﻤﺸﺎﮑل ﺴـﺘﻅﻬﺭ‬ ‫ﻝﻨﺎ ﻗﺎﺌﻤﺔ ﻤﻨﺒﺜﻘﺔ ﺘﻅﻬﺭ ﻤﺤﺎﻭﻝﺔ ﺍﻻﺘﺼﺎل‬ ‫ﺒﻴﻥ ﺍﻝﺠﻬﺎﺯﻴﻥ ﻭﻨﺠﺎﺡ ﻫـﺫﺍ ﺍﻻﺘـﺼﺎل‬ ‫ﻭﻫﻨﺎ ﻴﺼﺒﺢ ﺍﻻﺨﺘﺼﺎﺭ ﺍﻝﺫﻱ ﻭﻀﻌﻨﺎﻩ ﻋﻠﻰ ﺴﻁﺢ ﺍﻝﻤﮑﺘﺏ ﻤﻔﻌﻼﹰ‪.‬ﻨﺴﺘﻁﻴﻊ ﺍﻝﺘﺄﮑـﺩ ﻤـﻥ‬ ‫ﺍﻝﺩﺨﻭل ﺇﻝﻰ ﺍﻝﺠﻬﺎﺯ ﺍﻝﻤﻀﻴﻑ ﺒﺎﻝﺩﺨﻭل ﺇﻝﻰ ﻝﻭﺤﺔ ﺍﻝﺘﺤﮑﻡ ﻭﺍﺨﺘﻴـﺎﺭ ﺍﺘـﺼﺎﻻﺕ ﺸـﺒﮑﺔ‬ ‫ﺍﻻﺘﺼﺎل ﻭﺍﻹﻨﺘﺭﻨﺕ ﻓﻴﻅﻬﺭ ﺇﻀﺎﻓﺔ ﻝﺸﺒﮑﺔ ﺍﻹﻨﺘﺭﻨﺕ ﺍﻝﺘﻲ ﻨﺴﺘﺨﺩﻤﻬﺎ ﺍﺨﺘﺼﺎﺭ ﺇﻝﻰ ﺍﻝﺸﺒﮑﺔ‬ ‫ﺍﻝﻭﻫﻤﻴﺔ ﺍﻝﺘﻲ ﺃﻨﺸﺄﻨﺎﻫﺎ‪ .‬ﻤﻥ ﺨﻼل ﺍﻝﺸﺒﮑﺔ ﺍﻝﻭﻫﻤﻴﺔ ﻨﺴﺘﻁﻴﻊ ﺍﻝﻭﺼﻭل ﺇﻝﻰ ﺒﻴﺎﻨﺎﺕ ﺍﻝﺠﻬﺎﺯ‬ ‫ﺍﻝﻤﻀﻴﻑ ﺍﻝﻤﺼﺭﺡ ﺒﺎﻝﻭﺼﻭل ﺇﻝﻴﻬﺎ ﻓﻼ ﻨﺴﺘﻁﻴﻊ ﺍﻝﻌﺒﺙ ﺒﺎﻝﺒﻴﺎﻨﺎﺕ ﺍﻝﻤﺤﻤﻴﺔ ﻓﻲ ﺠﻬـﺎﺯﻩ‪،‬‬ ‫ﻭﺇﻤﮑﺎﻨﻴﺔ ﺍﻝﻭﺼﻭل ﻭﺍﻝﻨﻘل ﺃﻭ ﺍﻝﻨﺴﺦ ﺘﮑﻭﻥ ﻤﺤﺩﺩﺓ ﻤﻥ ﻗﺒل ﺒﺭﺘﻭﮑﻭﻻﺕ ﺍﻝﺸﺒﮑﺔ ﺍﻝﻭﻫﻤﻴﺔ‪.‬‬

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‫ﺘﮑﻭﻴﻥ ﻤﺼﺎﺩﻗﺔ ﺍﻝﻬﻭﻴﺔ ﻭﺍﻋﺩﺍﺩﺍﺕ ﺘﺸﻔﻴﺭ ﺍﻝﺒﻴﺎﻨﺎﺕ ﻻﺘﺼﺎل ﻁﻠﺏ ﻫﺎﺘﻔﻲ‪:‬‬ ‫ﻝﺘﮑﻭﻴﻥ ﻤﺼﺎﺩﻗﺔ ﺍﻝﻬﻭﻴﺔ ﻭﺇﻋﺩﺍﺩﺍﺕ ﺘﺸﻔﻴﺭ ﺍﻝﺒﻴﺎﻨﺎﺕ ﻻﺘﺼﺎل ﺍﻝﻁﻠﺏ ﺍﻝﻬﺎﺘﻔﻲ‬ ‫• ﺍﻓﺘﺢ ﺍﺘﺼﺎﻻﺕ ﺸﺒﮑﺔ ﺍﻻﺘﺼﺎل‪.‬‬ ‫• ﺍﻨﻘﺭ ﻓﻭﻕ ﺍﺘﺼﺎل ﺍﻝﻁﻠﺏ ﺍﻝﻬﺎﺘﻔﻲ ﺍﻝﺫﻱ ﺘﺭﻴﺩ ﺘﮑﻭﻴﻨﻪ‪ ،‬ﺜـﻡ ﺘﺤـﺕ ﻤﻬـﺎﻡ ﺸـﺒﮑﺔ‬ ‫ﺍﻻﺘﺼﺎ‪،‬ل ﺍﻨﻘﺭ ﻓﻭﻕ ﺘﻐﻴﻴﺭ ﺇﻋﺩﺍﺩﺍﺕ ﻫﺫﺍ ﺍﻻﺘﺼﺎل‪.‬‬ ‫• ﻓﻲ ﺍﻝﺘﺒﻭﻴﺏ ﺍﻷﻤﺎﻥ‪ ،‬ﻗﻡ ﺒﺈﺠﺭﺍﺀ ﻭﺍﺤﺩ ﻤﻤﺎ ﻴﻠﻲ‪:‬‬ ‫• ﻝﺘﺤﺩﻴﺩ ﻤﺠﻤﻭﻋﺔ ﺃﺴﺎﻝﻴﺏ ﻤﺼﺎﺩﻗﺔ ﺍﻝﻬﻭﻴﺔ ﻭﻤﺘﻁﻠﺒﺎﺕ ﺘﺸﻔﻴﺭ ﺍﻝﺒﻴﺎﻨـﺎﺕ ﺍﻝﻤﮑﻭﻨـﺔ‬ ‫ﻤﺴﺒﻘﹰﺎ‪ ،‬ﺍﻨﻘﺭ ﻓﻭﻕ ﻨﻤﻭﺫﺠﻲ )ﺍﻹﻋﺩﺍﺩﺍﺕ ﺍﻝﻤﻭﺼﻰ ﺒﻬﺎ(‪ ،‬ﻭﻓﻲ ﺍﻝﺘﺤﻘﻕ ﻤﻥ ﺼـﺤﺔ‬ ‫ﻫﻭﻴﺘﻲ ﮑﺎﻝﺘﺎﻝﻲ‪ ،‬ﺍﻨﻘﺭ ﻓﻭﻕ ﺍﻷﺴﻠﻭﺏ ﺍﻝﺫﻱ ﺘﺭﻴﺩ ﺍﺴﺘﺨﺩﺍﻤﻪ ﻝﻠﺘﺤﻘﻕ‪.‬‬ ‫• ﺍﺴﺘﻨﺎﺩﹰﺍ ﺇﻝﻰ ﺘﺤﺩﻴﺩ ﺍﻝﺘﺤﻘﻕ ﻤﻥ ﺼﺤﺔ ﻫﻭﻴﺘﻲ‪ ،‬ﻴﻤﮑﻨﻙ ﺘﺤﺩﻴﺩ )ﺘﻤﮑـﻴﻥ( ﺃﻭ ﻤـﺴﺢ‬ ‫)ﺘﻌﻁﻴل( ﺨﺎﻨﺎﺕ ﺍﻻﺨﺘﻴﺎﺭ ﺍﺴﺘﺨﺩﺍﻡ ﺍﺴﻡ ﺘﺴﺠﻴل ﺍﻝﺩﺨﻭل ﺇﻝﻰ ‪ Windows‬ﻭﮑﻠﻤﺔ‬ ‫ﺍﻝﻤﺭﻭﺭ )ﻭﺍﻝﻤﺠﺎل ﺇﺫﺍ ﻭﺠﺩ( ﺘﻠﻘﺎﺌﻴﺎﹰ ﺃﻭ ﻤﻁﻠﻭﺏ ﺘﺸﻔﻴﺭ ﺍﻝﺒﻴﺎﻨﺎﺕ )ﻗﻁﻊ ﺍﻻﺘﺼﺎل ﺇﺫﺍ‬ ‫ﻝﻡ ﻴﺘﻡ ﺫﻝﻙ(‪.‬‬

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‫ﺇﻥ ﻝﻠﺸﺒﮑﺔ ﺍﻝﻼﺴﻠﮑﻴﺔ ﺃﺨﻁﺎﺭﺍﹰ ﺘﻬﺩﺩ ﺃﻤﻨﻬﺎ ﮑﻐﻴﺭﻫﺎ ﻤﻥ ﺍﻝﺸﺒﮑﺎﺕ‪ ،‬ﺴﻭﺍﺀ ﮑﺎﻨﺕ ﻫـﺫﻩ‬ ‫ﺍﻝﻤﺨﺎﻁﺭ ﻤﺸﺘﺭﮑﺔ ﺒﻴﻥ ﺍﻝﺸﺒﮑﺎﺕ ﺍﻝﺴﻠﮑﻴﺔ ﻭﺍﻝﻼﺴﻠﮑﻴﺔ ﺃﻭ ﮑﺎﻨﺕ ﻤﺨـﺎﻁﺭ ﻤﺨﺼـﺼﺔ ﺃﻭ‬ ‫ﻤﻭﺠﻭﺩﺓ ﻓﻘﻁ ﻓﻲ ﺍﻝﺸﺒﮑﺎﺕ ﺍﻝﻼﺴﻠﮑﻴﺔ ﻭﻤﺎ ﺘﺤﺘﻭﻴﻪ ﻤﻥ ﻤﻌﺎﻴﻴﺭ ﻭﻏﻴﺭﻫﺎ‪.‬‬ ‫ﻭﻫﻨﺎ ﺴﻨﺤﺎﻭل ﻗﺩﺭ ﺍﻹﻤﮑﺎﻥ ﺍﻝﺘﺭﮑﻴﺯ ﻋﻠﻰ ﺘﺄﻤﻴﻥ ﺍﻝﺒﻴﺌﺔ ﺍﻝﺸﺒﮑﻴﺔ ﺍﻝﻼﺴﻠﮑﻴﺔ ﻤﻥ ﺃﻏﻠﺏ‬ ‫ﺍﻝﻤﺨﺎﻁﺭ ﺍﻝﺘﻲ ﻗﺩ ﺘﻬﺩﺩﻫﺎ‪ .‬ﻓﻼ ﻴﻭﺠﺩ ﺃﻤﻥ ‪ %100‬ﻭﻝﮑﻥ ﻋﻠﻴﻨﺎ ﻗﺩﺭ ﺍﻹﻤﮑﺎﻥ ﺃﻥ ﻨﻘﺘـﺭﺏ‬ ‫ﻤﻥ ﻫﺫﻩ ﺍﻝﻨﺴﺒﺔ ﺒﺘﻨﻔﻴﺫ ﺒﻌﺽ ﺍﻷﻤﻭﺭ ﺍﻝﺘﻲ ﺴﺘﺴﺎﻋﺩ ﻋﻠﻰ ﺠﻌل ﺍﻝﺸﺒﮑﺔ ﺁﻤﻨﺔ ﻗﺩﺭ ﺍﻹﻤﮑﺎﻥ‪.‬‬ ‫ﻤﻥ ﺍﻝﻤﻌﺭﻭﻑ ﺃﻥ ﻤﻥ ﺃﺨﻁﺭ ﻤﺎ ﻴﻬﺩﺩ ﺍﻝﺸﺒﮑﺎﺕ ﻫﺫﻩ ﺍﻷﻴﺎﻡ ﻫـﻲ ﻫﺠﻤـﺎﺕ ﺤﺠـﺏ‬ ‫ﺍﻝﺨﺩﻤﺔ ﺍﻝﺘﻲ ﻗﺩ ﺘﺘﻌﺭﺽ ﻝﻬﺎ ﻭﻓﻲ ﮑﺜﻴﺭ ﻤﻥ ﺍﻷﺤﻴﺎﻥ ﻴﺼﻌﺏ ﺘﻔﺎﺩﻴﻬﺎ ﺇﻥ ﺘﻤﺕ ﺒـﺼﻭﺭﺓ‬ ‫ﺩﻗﻴﻘﺔ ﻭﻤﺭﮑﺯﺓ‪ .‬ﺇﻥ ﻤﻨﻔﺫﻱ ﻫﺠﻤﺎﺕ ﺤﺠﺏ ﺍﻝﺨﺩﻤﺔ ﺍﻝﻤﻭﺯﻋﺔ ‪ DDoS‬ﺃﻭ ‪Distributed‬‬ ‫‪ Service Denial of‬ﻴﺤﺘﺎﺠﻭﻥ ﺇﻝﻰ ﻋﺩﺩ ﮑﺒﻴﺭ ﻤﻥ ﺍﻷﺠﻬﺯﺓ ﻝﮑﻲ ﻴﻨﻔـﺫﻭﺍ ﻫﺠﻤـﺎﺘﻬﻡ‬ ‫ﻓﺘﺭﺍﻫﻡ ﻴﺒﺭﻤﺠﻭﻥ ﺒﺭﻤﺠﻴﺎﺕ ﺘﻌﻤل ﻋﻠﻰ ﺃﺘﻤﺘﺔ ﺍﻝﻬﺠﻭﻡ ﻭﺍﻻﺴﺘﻴﻼﺀ ﻋﻠﻰ ﺃﺠﻬﺯﺓ ﺍﻝﺤﺎﺴـﺏ‬ ‫ﻭﻤﻥ ﺜﻡ ﺍﻻﻨﺘﻘﺎل ﺇﻝﻰ ﺍﻷﺠﻬﺯﺓ ﺍﻝﻤﺠﺎﻭﺭﺓ ﻭﻏﻴﺭﻫﺎ ﺒﺼﻭﺭﺓ ﺘﻠﻘﺎﺌﻴﺔ ﺴﺭﻴﻌﺔ ﻭﺇﺫﺍ ﮑﺎﻥ ﺠﻬﺎﺯ‬ ‫ﺍﻝﺤﺎﺴﺏ ﻏﻴﺭ ﻤﺤﻤﻲ ﺒﺼﻭﺭﺓ ﮑﺎﻓﻴﺔ ﻓﺎﻨﻪ ﺴﻴﻘﻊ ﻀﻤﻥ ﻗﺎﺌﻤﺔ ﺍﻷﺠﻬﺯﺓ ﺍﻝﺘﻲ ﺘﻨﺘﻅﺭ ﺍﻷﻭﺍﻤﺭ‬ ‫ﻤﻥ ﺍﻝﻤﻬﺎﺠﻤﻴﻥ ﻝﺘﻨﻔﺫ ﺍﻝﻬﺠﻭﻡ‪ .‬ﻓﻲ ﺍﻝﻌﺎﺩﺓ ﻓﺎﻥ ﺍﻷﺠﻬﺯﺓ ﺍﻝﻤﺼﺎﺒﺔ ﻻ ﻴﺘﻡ ﺤﺫﻑ ﺍﻝﻤﻠﻔﺎﺕ ﻤﻨﻬﺎ‬ ‫ﻝﮑﻥ ﻴﺘﻡ ﺍﺴﺘﻌﻤﺎﻝﻬﺎ ﺠﻤﻴﻌﺎﹰ ﻓﻲ ﻭﻗﺕ ﻭﺍﺤﺩ ﻓﻲ ﺍﻝﻬﺠﻭﻡ ﻋﻠﻰ ﺸﺒﮑﺔ ﻤﻌﻴﻨﺔ ﺃﻭ ﻤﻭﻗﻊ ﻤﻌـﻴﻥ‬ ‫ﻭﺘﻠﻙ ﺍﻷﺠﻬﺯﺓ ﺘﺴﻤﻰ ﺒﺎل‪.zombies‬‬ ‫ﻤﻥ ﺃﮑﺜﺭ ﺍﻝﺠﻬﺎﺕ ﺍﻝﺘﻲ ﻴﻨﺼﺏ ﺍﻫﺘﻤﺎﻡ ﺍﻝﻤﻬﺎﺠﻤﻴﻥ ﻋﻠﻰ ﺍﻻﺴﺘﻴﻼﺀ ﻋﻠﻰ ﺃﺠﻬﺯﺘﻬﺎ ﻫﻲ‬ ‫ﺍﻝﺸﺭﮑﺎﺕ ﺍﻝﮑﺒﻴﺭﺓ ﻭﺍﻝﺠﺎﻤﻌﺎﺕ ﻭﺍﻝﮑﻠﻴﺎﺕ ﺍﻝﺘﻲ ﺘﺤﻤل ﻋﺩﺩ ﮑﺒﻴﺭ ﻤـﻥ ﺃﺠﻬـﺯﺓ ﺍﻝﺤﺎﺴـﺏ‬ ‫ﺍﻝﻤﺘﺼﻠﺔ ﺒﺎﻹﻨﺘﺭﻨﺕ ﺒﺸﮑل ﻤﺘﻭﺍﺼل ﻭﺇﻥ ﻝﻡ ﻴﺘﺨﺫ ﺍﻝﻤﺴﺅﻭﻝﻴﻥ ﻋﻥ ﻫﺫﻩ ﺍﻝﺸﺒﮑﺎﺕ ﺍﻝﺤـﺫﺭ‬ ‫ﻤﻥ ﺃﻤﻭﺭ ﻋﺩﻴﺩﺓ ﻓﺎﻥ ﻨﺴﺒﺔ ﺘﻌﺭﺽ ﺃﺠﻬﺯﺓ ﺸﺒﮑﺘﻬﻡ ﻝﻼﺸﺘﺭﺍﻙ ﻓﻲ ﻫﺠﻭﻡ ﺃﻤﺭ ﻭﺍﺭﺩ‪.‬‬

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‫ري‬

‫‪Wireless Networks‬‬

‫ﻭ ﺒﻤﺎ ﺃﻥ ﺍﻏﻠﺏ ﺍﻝﺸﺭﮑﺎﺕ ﻭﺍﻝﺠﺎﻤﻌﺎﺕ ﺒﺩﺃﺕ ﺒﺎﻝﺘﻭﺠﻪ ﺇﻝـﻰ ﺍﺴـﺘﻌﻤﺎل ﺍﻝـﺸﺒﮑﺎﺕ‬ ‫ﺍﻝﻼﺴﻠﮑﻴﺔ ﻓﺎﻥ ﻨﺴﺒﺔ ﺍﻝﺨﻁﺭ ﻓﻲ ﻀﻠﻭﻉ ﺃﺠﻬﺯﺘﻬﺎ ﺒﻁﺒﻴﻌﺔ ﺍﻝﺤﺎل ﺘﺭﺘﻔﻊ ﻷﺴـﺒﺎﺏ ﻋﺩﻴـﺩﺓ‬ ‫ﺃﻭﻝﻬﺎ ﺃﻥ ﺍﻷﺠﻬﺯﺓ ﻝﻥ ﺘﮑﻭﻥ ﻓﻲ ﺍﻝﻌﺎﺩﺓ ﻤﻭﺠﻭﺩﺓ ﻓﻲ ﻤﮑﺎﻥ ﺜﺎﺒﺕ ﺒل ﺘﺘﺤﺭﻙ ﻭﺭﺒﻤﺎ ﺘﺨﺭﺝ‬ ‫ﻤﻥ ﻤﺒﻨﻰ ﺍﻝﺸﺭﮑﺔ ﻨﻔﺴﻬﺎ! ﻝﺫﺍ ﻭﺠﺏ ﺍﻝﺤﺫﺭ ﻤﻥ ﺍﺘﺨﺎﺫ ﮑﺎﻓﺔ ﺍﻝﻭﺴﺎﺌل ﺍﻝﻤﻤﮑﻨﺔ ﻤـﻥ ﺠﻌﻝـ‬ ‫ﺍﻝﺸﺒﮑﺔ ﺍﻝﻼﺴﻠﮑﻴﺔ ﺁﻤﻨﺔ ﻗﺩﺭ ﺍﻝﻤﺴﺘﻁﺎﻉ‪.‬‬ ‫ﺇﻥ ﺍﻷﺠﻬﺯﺓ ﺍﻝﻤﺤﻤﻭﻝﺔ ﺍﻝﺘﻲ ﺘﻤﻠﻙ ﮑﺭﺕ ﺸﺒﮑﺔ ﻻﺴﻠﮑﻲ ﻤﻭﺼل ﺒﻤﻘﻭﻱ ﻝﻺﺭﺴـﺎل‪,‬‬ ‫ﺒﺈﻤﮑﺎﻨﻬﺎ ﺃﻥ‬

‫ﻓﻲ ﻨﻘل ﺍﻝﻤﻠﻔﺎﺕ ﻭﺍﻝﺘﻌﺎﻤل ﮑﻤﺎ ﻝﻭ ﮑﺎﻨﺕ ﻓـﻲ ﻤﺒﻨـﻰ ﺍﻝﺠﺎﻤﻌـﺔ ﺃﻭ‬ ‫ﺘﺸﺎﺭﻙ‬

‫ﺍﻝﺸﺭﮑﺔ ﺃﻭ ﺍﻝﮑﻠﻴﺔ ﻭﻓﻲ ﺍﻝﺤﻘﻴﻘﺔ ﻤﻥ ﺍﻝﻤﻤﮑﻥ ﺃﻥ ﺘﺒﻌﺩ ﮑﻴﻠﻭﻤﺘﺭﺍﺕ ﻋﻨﻬﺎ! ﻭﺇﺫﺍ ﮑﺎﻨﺕ ﻨﻘـﺎﻁ‬ ‫ﺍﻻﺘﺼﺎل ﺍﻝﻤﻭﺠﻭﺩﺓ ﻓﻲ ﺍﻝﻤﺅﺴﺴﺔ ﺃﻭ ﺍﻝﺠﺎﻤﻌﺔ ﻝﻡ ﻴﺘﻡ ﺘﻀﺒﻴﻁ ﺇﻋﺩﺍﺩﺍﺘﻬﺎ ﺒﻁﺭﻴﻘﺔ ﺴﻠﻴﻤﺔ ﻭﻝﻡ‬ ‫ﻴﺘﻡ ﺘﻌﺩﻴل ﺍﻹﻋﺩﺍﺩﺍﺕ ﺍﻻﻓﺘﺭﺍﻀﻴﺔ ﺍﻝﻤﻌﺭﻭﻓﺔ ﻝﺩﻯ ﮑل ﺒﺎﺤﺙ‪ ,‬ﻓﺎﻥ ﺃﻱ ﺸﺨﺹ ﻋﻠﻰ ﺒﻌـﺩ‬ ‫ﺃﻤﻴﺎل )ﺒﺎﺴﺘﺨﺩﺍﻡ ﻤﻘﻭﻱ ﻝﻺﺭﺴﺎل( ﻴﺴﺘﻁﻴﻊ ﺍﻝﺩﺨﻭل ﺒﮑل ﺴﻬﻭﻝﺔ ﻋﻠﻰ ﺍﻝﺸﺒﮑﺔ‪.‬‬ ‫ﺇﻥ ﺃﻏﻠﺏ ﺍﻷﻤﻭﺭ ﺍﻝﺘﻲ ﻤﻥ ﺍﻝﻤﻤﮑﻥ ﺃﻥ ﻴﺘﻡ ﺍﺴﺘﻐﻼﻝﻬﺎ ﻫﻲ ﺍﻹﻋﺩﺍﺩﺍﺕ ﺍﻻﻓﺘﺭﺍﻀـﻴﺔ‬ ‫ﻝﻨﻘﺎﻁ ﺍﻻﺘﺼﺎل ‪ ,Points Access‬ﻭﻓﻲ ﻤﺎ ﻴﻠﻲ ﺒﻌﺽ ﺍﻷﻤﻭﺭ ﺍﻝﺘﻲ ﺴﺘﺴﺎﻋﺩ ﻓﻲ ﺘﻘﻠﻴل‬ ‫ﻤﺨﺎﻁﺭ ﺍﻹﻋﺩﺍﺩﺍﺕ ﺍﻻﻓﺘﺭﺍﻀﻴﺔ‪:‬‬ ‫ﻤ‪‬ﻌﺭﻑ ﺍﻝﺨﺩﻤﺔ ﺃﻭ ﺍﻝـ ‪SSID‬‬ ‫ﺍﻝـ ‪ SSID‬ﺃﻭ ﺍﻝـ ‪IDentifier Set Service‬‬

‫ﻤﻌّ◌ﺭﻑ ﺍﻝﺨﺩﻤﺔ‪ .‬ﺃﻥ ﮑﻝـ‬ ‫ﺘﻌﻨﻲ‬

‫ﻨﻘﻁﺔ ﺍﺘﺼﺎل ﺘﻤﻠﻙ ﻤﻌﺭﻑ ﻴﮑﻭﻥ ﻋﺒﺎﺭﺓ ﻋﻥ ﮑﻠﻤﺔ ﺃﻭ ﺭﻗﻡ ﺃﻭ ﺨﻠﻴﻁ ﺒﻴﻥ ﺤﺭﻭﻑ ﻭﺃﺭﻗﺎﻡ‪.‬‬ ‫ﻴﻘﻭﻡ ﻫﺫﺍ ﺍﻝﻤﻌﺭﻑ ﺒﺎﻝﺘﻌﺭﻴﻑ ﻋﻥ ﻨﻘﻁﺔ ﺍﻻﺘﺼﺎل ﻭﻝﻨﻔﺭﺽ ﺃﻥ ﻨﻘﻁﺔ ﺍﺘﺼﺎل ﻤﻌﻴﻨﺔ ﺘﻤﻠﻙ‬ ‫‪ SSID‬ﻤﻌﻴﻥ ﻋﻠﻰ ﺴﺒﻴل ﺍﻝﻤﺜﺎل ﻫﻭ ﺍﻷﮑﺎﺩﻴﻤﻴﺔ‪ .‬ﺇﻥ ﺃﻱ ﺸﺨﺹ ﻤﻭﺠـﻭﺩ ﻓـﻲ ﻤـﺩﻯ‬ ‫ﺍﻝﺘﻐﻁﻴﺔ ﺍﻝﺘﻲ ﺘﻐﻁﻴﻬﺎ ﻨﻘﻁﺔ ﺍﻻﺘﺼﺎل )ﺍﻝﻤﺩﻯ ﻴﻌﺘﻤﺩ ﻋﻠﻰ ﺃﻤﻭﺭ ﻋﺩﻴﺩﺓ ﻗﺩ ﺘﺼل ﺇﻝﻰ ﮑﻴﻠﻭ‬ ‫ﻤﺘﺭﺍﺕ ﺴﻭﺍﺀ ﮑﺎﻥ ﻓﻲ ﻨﻔﺱ ﺍﻝﺒﻴﺕ ﺃﻭ ﺍﻝﻤﺒﻨﻰ ﺃﻭ ﮑﺎﻥ ﻓﻲ ﺍﻝـﺸﺎﺭﻉ ﺍﻝﻤﺠـﺎﻭﺭ ﻝﻠﺒﻴـﺕ(‬ ‫ﻴﺴﺘﻁﻴﻊ ﺃﻥ ﻴﺩﺨل ﺇﻝﻰ ﺍﻝﺸﺒﮑﺔ ﺍﻝﺨﺎﺼﺔ ﺒﻨﻘﻁﺔ ﺍﻻﺘﺼﺎل ﺫﺍﺕ ﺍﻝﻤﻌﺭﻑ )ﺍﻷﮑﺎﺩﻴﻤﻴـﺔ( ﺇﺫﺍ‬ ‫ﻋﺭﻑ ﺃﻥ ﮑﻠﻤﺔ )ﺍﻷﮑﺎﺩﻴﻤﻴﺔ( ﻫﻲ ﺍﻝـ ‪ SSID‬ﺍﻝﺨﺎﺹ ﺒﻬﺎ‪ .‬ﺃﻏﻠﺏ ﻨﻘﺎﻁ ﺍﻻﺘﺼﺎل ﺘﺤﻤﻝـ‬ ‫‪38‬‬ ‫تو ا‬

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‫ري‬

‫‪Wireless Networks‬‬

‫ﺇﻋﺩﺍﺩﺍﺕ ﺍﻓﺘﺭﺍﻀﻴﺔ ﻭﻴﮑﻭﻥ ﺍﻝﻤﻌﺭﻑ ﻝﻬﺎ ﻤﻌﺭﻭﻓ ﹰﺎ ﻭﻓﻲ ﺍﻝﻐﺎﻝﺏ ﻴﮑﻭﻥ ﮑﻠﻤﺔ ‪ .default‬ﺇﺫﺍ‬ ‫ﻝﻡ ﻴﺘﻡ ﺘﻐﻴﻴﺭ ﻫﺫﺍ ﺍﻝﻤﻌﺭﻑ ﺇﻝﻰ ﺃﻱ ﺸﻲ ﺁﺨﺭ‪ ,‬ﻓﺎﻥ ﺃﻱ ﺸﺨﺹ ﻴﻘﻊ ﻓﻲ ﻀﻤﻥ ﻤﺩﻯ ﻨﻘﻁﺔ‬ ‫ﺍﻻﺘﺼﺎل ﻴﺴﺘﻁﻴﻊ ﺍﻝﺩﺨﻭل ﻝﻠﺸﺒﮑﺔ ﺍﻝﺨﺎﺼﺔ ﺒﻬﺎ ﺒﺩﻭﻥ ﻋﻭﺍﺌﻕ!‬ ‫ﻤﻥ ﺍﻷﻤﻭﺭ ﺍﻝﻤﻭﺠﻭﺩﺓ ﻓﻲ ﺍﻹﻋﺩﺍﺩﺍﺕ ﺍﻻﻓﺘﺭﺍﻀﻴﺔ ﺍﻝﺨﺎﺼﺔ ﺒﺎﻝـ ‪ SSID‬ﻫﻭ ﺍﻝــ‬ ‫‪ .Broadcasting SSID‬ﺘﻘﻭﻡ ﻨﻘﺎﻁ ﺍﻻﺘﺼﺎل ﺒﺎﻝﺘﻌﺭﻴﻑ ﻋﻥ ﻨﻔﺴﻬﺎ ﺒﺸﮑل ﻤﺴﺘﻤﺭ ﻋﻠﻰ‬ ‫ﻤﺩﻯ ﺍﻝﺘﻐﻁﻴﺔ ﺍﻝﺘﻲ ﺘﻐﻁﻴﻪ ﻓﺘﻘﻭﻡ ﺒﺼﻭﺭﺓ ﻤﺴﺘﻤﺭﺓ ﺒﺈﺭﺴﺎل ﺇﺸﺎﺭﺍﺕ ﺘﻘﻭﻡ ﺒﺎﻝﺘﻌﺭﻴﻑ ﻋـﻥ‬ ‫ﻨﻔﺴﻬﺎ ﻭﺒﻤﻌ ّ◌ﺭﻓﻬﺎ ﺍﻝﺨﺎﺹ‪ .‬ﺒﻬﺫﻩ ﺍﻝﻁﺭﻴﻘﺔ ﻴﻤﮑﻥ ﻷﻱ ﺸﺨﺹ ﻴﻤﻠـﻙ ﺠﻬـﺎﺯ ﺨـﺎﺹ ﺃﻭ‬ ‫ﮑﻤﺒﻴﻭﺘﺭ ﻤﺤﻤﻭل ﺒﻪ ﮑﺭﺕ ﺸﺒﮑﺔ ﻻﺴﻠﮑﻴﺔ ﺃﻥ ﻴﺘﺠﻪ ﺇﻝﻰ ﺍﻝﻤﻨﻁﻘﺔ ﺍﻝﺘـﻲ ﺘﻐﻁﻴﻬـﺎ ﻨﻘﻁـﺔ‬ ‫ﺍﻻﺘﺼﺎل ﻓﻴﺤﺼل ﺒﺸﮑل ﺘﻠﻘﺎﺌﻲ ﻋﻠﻰ ﺍﻹﺸﺎﺭﺓ ﻤﻊ ﺭﻗﻡ ﺍﻝﻤﻌﺭﻑ ﻓﻴﻌﺭﻑ ﺍﻨﻪ ﺍﻵﻥ ﻴﻤﮑﻨـﻪ‬ ‫ﺍﻻﺘﺼﺎل ﺒﺸﺒﮑﺔ ﻨﻘﻁﺔ ﺍﻻﺘﺼﺎل )ﺍﻷﮑﺎﺩﻴﻤﻴﺔ( ﻤﻥ ﻤﻭﻗﻌﻪ‪ .‬ﻴﺠﺏ ﺘﻌﻁﻴل ﻫـﺫﻩ ﺍﻝﺨﺎﺼـﻴﺔ‬ ‫ﺍﻝﺘﻲ ﺘﺄﺘﻲ ﺒﺼﻭﺭﺓ ﺍﻓﺘﺭﺍﻀﻴﺔ ﻓﻲ ﺍﻝﻌﺎﺩﺓ ﺤﺘﻰ ﻻ ﻴﺘﻤﮑﻥ ﻀﻌﺎﻑ ﺍﻝﻨﻔـﻭﺱ ﻤـﻥ ﺍﻝـﺫﻴﻥ‬ ‫ﻴﻤﻠﮑﻭﻥ ﺃﺠﻬﺯﺓ ﻤﺤﻤﻭﻝﺔ ﺫﺍﺕ ﮑﺭﻭﺕ ﺸﺒﮑﺔ ﻻﺴﻠﮑﻴﺔ ﻤﻥ ﺍﻻﻗﺘـﺭﺍﺏ ﻭﻤﻌﺭﻓـﺔ ﺍﻷﻤـﺎﮑﻥ‬ ‫)ﺍﻝﻘﺭﻴﺒﺔ( ﻤﻥ ﺍﻝﻤﻨﺯل ﺍﻭ ﺍﻝﻤﺒﻨﻰ ﻭﺍﻝﺘﻲ ﻤﻥ ﺨﻼﻝﻬﺎ ﻴﺴﺘﻁﻴﻌﻭﻥ ﺍﻝـﺩﺨﻭل ﻋﻠـﻰ ﺍﻝـﺸﺒﮑﺔ‬ ‫ﺍﻝﻼﺴﻠﮑﻴﺔ‪ .‬ﻴﻔﻀل ﻗﺩﺭ ﺍﻹﻤﮑﺎﻥ ﺘﻐﻴﻴﺭ ﺍﻝﻤﻌﺭﻑ ﺒﺼﻭﺭﺓ ﻤﺴﺘﻤﺭﺓ ﺒﻴﻥ ﺤﻴﻥ ﻭﺁﺨﺭ ﺤﺘﻰ ﺇﻥ‬ ‫ﺤﺼل ﺃﺤﺩ ﺍﻝﺫﻴﻥ ﻴﺤﺎﻭﻝﻭﻥ ﺍﺨﺘﺭﺍﻕ ﺍﻝﺸﺒﮑﺔ ﻋﻠﻰ ﺍﻝﻤﻌﺭﻑ ﺍﻝﺨﺎﺹ ﺒﻨﻘﻁﺔ ﺍﻻﺘﺼﺎل ﻓـﻲ‬ ‫ﻭﻗﺕ ﻤﻌﻴﻥ ﻓﺎﻨﻪ ﻋﻨﺩ ﺘﻐﻴﻴﺭﻩ ﺒﺼﻭﺭﺓ ﻤﺴﺘﻤﺭﺓ ﺴﺘﺼﻌﺏ ﻤﻬﻤﺘﻪ ﺍﮑﺜﺭ‪.‬‬ ‫ﻤﻥ ﺍﻝﻤﻤﮑﻥ ﺃﻴﻀﺎ ﺘﻘﻠﻴل ﻨﺴﺒﺔ ﺍﻹﺭﺴﺎل ﻝﻨﻘﻁﺔ ﺍﻻﺘﺼﺎل ﺒﺤﻴﺙ ﺃﻥ ﻴﮑﻭﻥ ﻤﺩﺍﻫﺎ ﻗﺩﺭ‬ ‫ﺍﻹﻤﮑﺎﻥ ﻋﻠﻰ ﺍﻝﻤﺤﺩﻭﺩ ﺍﻝﻤﻁﻠﻭﺒﺔ ﻭﺍﻝﻤﺴﻤﻭﺡ ﺒﻬﺎ ﻻ ﺃﻥ ﺘﺘﺨﻁﻰ ﻫﺫﻩ ﺍﻝﺤـﺩﻭﺩ ﻭﺘﻐﻁـﻲ‬ ‫ﻤﺴﺎﺤﺎﺕ ﺨﺎﺭﺝ ﻨﻁﺎﻕ ﺍﻝﻤﻨﺯل ﺃﻭ ﺍﻝﺸﺭﮑﺔ ﻭﺍﻝﺘﻲ ﻗﺩ ﻴﺴﺘﻐﻠﻬﺎ ﺍﻝﺒﻌﺽ ﻓﻲ ﺍﻝﺩﺨﻭل ﻝﻠﺸﺒﮑﺔ‬ ‫ﺍﻝﺨﺎﺼﺔ‪.‬‬ ‫ﻨﺴﺘﻁﻴﻊ ﺘﻤﺜﻴل ﻤﺴﺄﻝﺔ ﺨﺭﻭﺝ ﻤﺩﻯ ﺍﻝﺘﻐﻁﻴﺔ ﻋﻥ ﺤﺩﻭﺩ ﺍﻝﻤﺅﺴﺴﺔ ﺃﻭ ﺍﻝﻤﻨـﺯل ﺇﻝـﻰ‬ ‫ﻤﺴﺎﻓﺎﺕ ﻻ ﺩﺍﻋﻲ ﻝﻬﺎ ﮑﻭﺼﻭل ﺍﻝﻤﺩﻯ ﺇﻝﻰ ﺍﻝﺸﺎﺭﻉ ﺍﻝﻤﺠﺎﻭﺭ ﺒﺘﻭﺯﻴﻊ ﺃﺴـﻼﻙ ﻭﮑـﺒﻼﺕ‬ ‫ﺨﺎﺼﺔ ﺒﺎﻝﺸﺒﮑﺔ ﺍﻝﺩﺍﺨﻠﻴﺔ ﻤﺎ ﻋﻠﻰ ﺍﻝﻨﺎﺱ ﺇﻻ ﺃﻥ ﻴﺤﻀﺭﻭﺍ ﺃﺠﻬﺯﺘﻬﻡ ﻭﻴﻭﺼـﻠﻭﻥ ﮑـﺭﻭﺕ‬

‫‪39‬‬ ‫تو ا‬

‫ھ نا‬

‫ري‬

‫‪Wireless Networks‬‬

‫ﺍﻝﺸﺒﮑﺔ ﺒﺎﻝﮑﺒﻼﺕ ﻭﺍﻷﺴﻼﻙ ﻭﻴﺩﺨﻠﻭﻥ ﻋﻠﻰ ﺍﻝﺸﺒﮑﺔ ﺍﻝﺩﺍﺨﻠﻴﺔ ﻭﻫﻡ ﺠﺎﻝﺴﻭﻥ ﻓﻲ ﺍﻝـﺸﺎﺭﻉ‬ ‫ﺍﻝﻤﺠﺎﻭﺭ!‬

‫ﻓﻠﺘﺭﺓ ﺍﻝـ ‪MAC Address‬‬ ‫ﺍﻝـ ‪ MAC Address‬ﺃﻭ ﺍﻝــ ‪ Media Access Control Address‬ﻫـﻭ‬ ‫ﺍﻝﻌﻨﻭﺍﻥ ﺍﻝﻔﻴﺯﻴﺎﺌﻲ ﻝﮑﺭﻭﺕ ﺍﻝﺸﺒﮑﺔ‪ .‬ﮑل ﮑﺭﺕ ﺸﺒﮑﺔ ﻓﻲ ﺍﻝﻌﺎﻝﻡ ﻴﺤﻤل ﺭﻗﻡ ﻴﻤﻴـﺯﻩ ﻋـﻥ‬ ‫ﻏﻴﺭﻩ‪ ,‬ﺘﻘﻭﻡ ﺍﻝﺸﺭﮑﺎﺕ ﺍﻝﻤﻨﺘﺠﺔ ﺒﻭﻀﻊ ﺃﺭﻗﺎﻡ ﺨﺎﺼﺔ ﻋﻠﻰ ﺃﺴﺎﺱ ﻨﻅﺎﻡ ﺍﻝﻬﮑـﺱ ﻝﺘﻤﻴـﺯ‬ ‫ﮑﺭﻭﺕ ﺍﻝﺸﺒﮑﺔ ﻋﻥ ﺒﻌﻀﻬﺎ ﻭﻤﻥ ﺍﻝﻤﻔﺘﺭﺽ ﺃﻥ ﻻ ﺘﮑﻭﻥ ﻫﺫﻩ ﺍﻷﺭﻗﺎﻡ ﻤﮑﺭﺭﺓ ﺃﺒﺩﺍﹰ‪ .‬ﺒﻁﺒﻴﻌﺔ‬ ‫ﺍﻝﺤﺎل ﻨﻘﻁﺔ ﺍﻻﺘﺼﺎل ﺘﻌﺘﺒﺭ ﻤﻥ ﺍﻝﻁﺒﻘﺔ ﺍﻝﺜﺎﻨﻴﺔ ﻓﻲ ﺍﻝـ ‪ OSI Model‬ﺃﻭ ﺍﻝــ ‪Open‬‬ ‫‪ System Interconnect‬ﻴﻌﻨﻲ ﻓﻲ ﻁﺒﻘﺔ ﺍﻝـ ‪ Data Link‬ﮑﺎﻝﺴﻭﻴﺘﺸﺎﺕ ﻓﺎﻥ ﺘﻌﺎﻤﻠﻬﺎ‬ ‫ﻴﮑﻭﻥ ﻤﻊ ﺍﻝـ ‪ MAC Address‬ﻭﻝﻴﺱ ﻤـﻊ ﺍﻝــ ‪ .IP Address‬ﻭﻫﻨـﺎ ﻴـﺴﺘﻁﻴﻊ‬ ‫ﻴﺴﻤﺢ ﻝﻬـﺎ ﺒﺎﺴـﺘﺨﺩﺍﻡ ﻨﻘﻁـﺔ‬ ‫ﺍﻝﻤﺴﺅﻭل ﻋﻥ ﺍﻝﺸﺒﮑﺔ ﺍﻝﻼﺴﻠﮑﻴﺔ ﺃﻥ ﻴﺤﺩﺩ ﺍﻷﺠﻬﺯﺓ‬ ‫ﺍﻝﺘﻲ‬ ‫ﺍﻻﺘﺼﺎل ﺍﻝﺨﺎﺼﺔ ﺒﻪ‪.‬‬ ‫ﮑﻤﺎ ﻨﻌﺭﻑ ﻓﺎﻥ ﮑل ﺠﻬﺎﺯ ﺤﺘﻰ ﻴﺘﺼل ﺒﺎﻝﺸﺒﮑﺔ ﺍﻝﻼﺴﻠﮑﻴﺔ ﻴﺠﺏ ﺃﻥ ﻴﺤﺘﻭﻱ ﻋﻠـﻰ‬ ‫ﮑﺭﺕ ﺸﺒﮑﺔ ﻻﺴﻠﮑﻴﺔ ﻭﮑل ﮑﺭﺕ ﺸﺒﮑﺔ ﻻﺴﻠﮑﻴﺔ ﺘﻤﻠﻙ ﺭﻗﻡ ﺨﺎﺹ ﻤﻤﻴﺯ ﻭﻫﻭ ﺍﻝـ ‪MAC‬‬ ‫‪ Address‬ﻭﻤﻥ ﺍﻝﻤﻔﺘﺭﺽ ﺃﻥ ﺍﻝﻤﺴﺅﻭل ﻋﻥ ﺍﻝﺸﺒﮑﺔ ﻴﻌﻲ ﻭﻴﻌﻠﻡ ﻋﺩﺩ ﺍﻷﺠﻬﺯﺓ ﺍﻝﻤﻭﺠﻭﺩﺓ‬ ‫ﻝﺩﻴﻪ ﺃﻭ ﻝﺩﻯ ﺸﺭﮑﺘﻪ ﻭﺍﻝﺘﻲ ﻴﺭﻴﺩﻫﺎ ﺃﻥ ﺘﺴﺘﺨﺩﻡ ﺸﺒﮑﺘﻪ ﺍﻝﻼﺴﻠﮑﻴﺔ‪ .‬ﻋﻨﺩﻫﺎ ﻴﺴﺘﻁﻴﻊ ﻓﻠﺘـﺭﺓ‬ ‫ﺍﺴﺘﺨﺩﺍﻡ ﻨﻘﻁ ﺍﻻﺘﺼﺎل ﻝﺩﻴﻪ ﻭﻴﺤﺩﺩ ﺍﻷﺠﻬﺯﺓ ﺒﻭﺍﺴﻁﺔ ﺇﻀﺎﻓﺔ ﺃﺭﻗﺎﻡ ﺍﻝـ‪ MAC‬ﺍﻝﺨﺎﺼـﺔ‬ ‫ﺒﻬﺫﻩ ﺍﻷﺠﻬﺯﺓ ﻓﻲ ﻗﺎﺌﻤﺔ ﺍﻷﺠﻬﺯﺓ ﺍﻝﻤﺴﻤﻭﺡ ﻝﻬﺎ ﺒﺎﺴـﺘﺨﺩﺍﻡ ﺍﻝـﺸﺒﮑﺔ ﺃﻭ‬

‫ﻨﻘـﻁ‬ ‫ﺍﺴـﺘﺨﺩﺍﻡ‬

‫ﺍﻻﺘﺼﺎل ﻭﻻ ﻴﺴﻤﺢ ﺒﻐﻴﺭ ﻫﺫﻩ ﺍﻷﺠﻬﺯﺓ ﻤﻬﻤﺎ ﮑﺎﻨﺕ ﺒﺎﺴﺘﺨﺩﺍﻡ ﻨﻘﺎﻁ ﺍﻻﺘـﺼﺎل ﺍﻝﺨﺎﺼـﺔ‬ ‫ﺒﺸﺒﮑﺘﻪ‪.‬‬ ‫ﺘﺸﻔﻴﺭ ﺍﻝﺒﻴﺎﻨﺎﺕ ﺒﺎﺴﺘﺨﺩﺍﻡ ﺍﻝـ ‪WEP‬‬

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‫‪Wireless Networks‬‬

‫ﺃﻏﻠﺏ ﻨﻘﻁ ﺍﻻﺘﺼﺎل ﺘﻤﻠﻙ ﺇﻤﮑﺎﻨﻴﺔ ﺍﻝﺘﻌﺎﻤل ﻤﻊ ﺍﻝﺒﻴﺎﻨﺎﺕ ﺍﻝﻤﺸﻔﺭﺓ‪ .‬ﺒﺎﺴﺘﺨﺩﺍﻡ ﺘﻘﻨﻴـﺔ‬ ‫ﺍﻝـ‪ WEP‬ﺃﻭ ‪ Wired Equivalent Privacy‬ﻓﺎﻥ ﺘﻔﻌﻴﻠﻬﺎ ﻓﻲ ﻨﻘﻁﺔ ﺍﻻﺘﺼﺎل ﻴﻤﮑـﻥ‬ ‫ﺘﺸﻔﻴﺭ ﺍﺴﺘﻼﻡ ﻭﺘﻤﺭﻴﺭ ﺍﻝﺒﻴﺎﻨﺎﺕ ﺍﻝﻤﺸﻔﺭﺓ ﻓﻘﻁ‪ .‬ﻝﺫﺍ ﻴﺠﺏ ﻋﻠﻰ ﮑل ﻤﺴﺘﺨﺩﻡ ﻴﺭﻴﺩ ﺍﺴﺘﺨﺩﺍﻡ‬ ‫ﺍﻝﺸﺒﮑﺔ ﺍﻝﻼﺴﻠﮑﻴﺔ ﺃﻥ ﻴﻔﻌل ﺨﺎﺼﻴﺔ ﺍﻝـ ‪ WEP‬ﺃﻱ ﺍﻝﺘﺸﻔﻴﺭ ﻓﻲ ﺠﻬﺎﺯﻩ ﮑﻲ ﻴـﺘﻡ ﺘﺒـﺎﺩل‬ ‫ﺍﻝﺒﻴﺎﻨﺎﺕ ﺒﺼﻭﺭﺓ ﻤﺸﻔﺭﺓ ﺘﺼﻌﺏ ﻓﻲ ﻤﻌﻅﻡ ﺍﻷﺤﻴﺎﻥ ﻤﻌﺭﻓﺔ ﻤﺤﺘﻭﺍﻫﺎ ﺇﻥ ﺘﻡ ﻨﺴﺦ ﻫـﺫﻩ‬ ‫ﺍﻝﺒﻴﺎﻨﺎﺕ ﺃﺜﻨﺎﺀ ﻤﺭﻭﺭﻫﺎ ﺒﻴﻥ ﺍﻷﺠﻬﺯﺓ‪.‬‬ ‫ﻭ ﮑﺨﻁ ﺩﻓﺎﻉ ﺜﺎﻨﻲ ﻋﻨﺩ ﺍﺴﺘﺨﺩﺍﻡ ﻤﻴﺯﺓ ﺍﻝﺘﺸﻔﻴﺭ ﻴﺠﺏ ﺘﺒﺎﺩل ﻤﻔﺘﺎﺡ ﺍﻝﺘﺸﻔﻴﺭ ﺍﻝﻤﺴﻤﻰ‬ ‫ﺒـ ‪ WEP Key‬ﻓﻬﻭ ﻋﺒﺎﺭﺓ ﻋﻥ ﺃﺭﻗﺎﻡ ﻋﻠﻰ ﺃﺴﺎﺱ ‪ Hex‬ﺘﺤﺩﺩ ﺩﺭﺠﺔ ﺍﻝﺘﺸﻔﻴﺭ ﻭﮑﻠﻤـﺎ‬ ‫ﺯﺍﺩ ﺤﺠﻡ ﺍﻝﺭﻗﻡ ﺯﺍﺩﺕ ﺼﻌﻭﺒﺔ ﮑﺴﺭ ﺍﻝﺘﺸﻔﻴﺭ ﻭﺃﻴﻀ ﹰﺎ ﺯﺍﺩﺕ ﺍﻝﻤﺩﺓ ﺍﻝﺘﻲ ﻴﺘﻡ ﻨﻘل ﺍﻝﺒﻴﺎﻨـﺎﺕ‬ ‫ﺒﻌﺩ ﺘﺸﻔﻴﺭﻫﺎ ﻭﺍﺴﺘﻼﻤﻬﺎ ﻭﻤﻥ ﺜﻡ ﻓﻙ ﺘﺸﻔﻴﺭﻫﺎ‪ .‬ﻭﻴﻌﺘﺒﺭ ﺍﻝﻤﻔﺘﺎﺡ ﺨﻁ ﺩﻓﺎﻉ ﺜﺎﻨﻲ ﻷﻨﻪ ﻴﺠﺏ‬ ‫ﻋﻠﻰ ﺍﻷﻁﺭﺍﻑ ﺍﻝﻤﺴﺘﺨﺩﻤﺔ ﻝﻠﺸﺒﮑﺔ ﻤﻌﺭﻓﺔ ﻫﺫﺍ ﺍﻝﻤﻔﺘﺎﺡ ﮑﻲ ﻴﺘﻡ ﺘﺸﻔﻴﺭ ﺍﻝﺒﻴﺎﻨـﺎﺕ ﻋﻠـﻰ‬ ‫ﺃﺴﺎﺴﻪ ﻭﻴﻔﻀل ﺘﻐﻴﻴﺭﻩ ﺒﻴﻥ ﻓﺘﺭﺓ ﻭﺃﺨﺭﻯ ﺤﺘﻰ ﺇﻥ ﻭﻗﻊ ﻓﻲ ﻴﺩ ﺃﺤﺩ ﺍﻝﻤﺘﻁﻔﻠﻴﻥ ﻓﺎﻨـﻪ ﻝـﻥ‬ ‫ﻴﺴﺘﺨﺩﻤﻪ ﻝﻔﺘﺭﺓ ﻁﻭﻴﻠﺔ‪.‬‬ ‫ﺍﻝﮑﻠﻤﺔ ﺍﻝﺴﺭﻴﺔ ﺍﻻﻓﺘﺭﺍﻀﻴﺔ ‪Default Password‬‬ ‫ﺘﺄﺘﻲ ﻨﻘﻁ ﺍﻻﺘﺼﺎل ﻤﻥ ﺍﻝﺸﺭﮑﺎﺕ ﺍﻝﻤﻨﺘﺠﺔ ﻝﻬﺎ ﺒﮑﻠﻤﺔ ﺴﺭﻴﺔ ﻤﻌﻴﻨﺔ ﻤﻭﺤﺩﺓ ﻭﻤﻌﺭﻭﻓﺔ‬ ‫ﻴﺠﺩﻫﺎ ﺍﻝﻤﺴﺘﺨﺩﻡ ﻓﻲ ﺍﻝﺩﻝﻴل ﺍﻝﺨﺎﺹ ﺒﺎل ‪ Access Point‬ﻭﻓﻲ ﺒﻌﺽ ﺍﻷﺤﻴـﺎﻥ ﺘﮑـﻭﻥ‬ ‫ﺍﻝﮑﻠﻤﺔ ﺍﻝﺴﺭﻴﺔ ﺨﺎﻝﻴﺔ ﻴﻌﻨﻲ ﺃﻥ ﻋﻨﺩ ﺘﺴﺠﻴل ﺍﻝﺩﺨﻭل ﻝﻨﻘﻁﺔ ﺍﻻﺘﺼﺎل ﻝﺘﻐﻴﻴـﺭ ﺍﻹﻋـﺩﺍﺩﺍﺕ‬ ‫ﻴﮑﻭﻥ ﺍﺴﻡ ﺍﻝﻤﺴﺘﺨﺩﻡ ﻫﻭ ﻤﺜﻼ ‪ admin‬ﻭﺍﻝﮑﻠﻤﺔ ﺍﻝﺴﺭﻴﺔ ﻏﻴﺭ ﻤﻭﺠﻭﺩﺓ! ﻤﻥ ﺍﻝﻭﺍﻀﺢ ﺍﻨـﻪ‬ ‫ﻴﺠﺏ ﺘﻐﻴﻴﺭﻫﺎ ﺇﻝﻰ ﮑﻠﻤﺔ ﺴﺭﻴﺔ ﺼﻌﺒﺔ ﻤﮑﻭﻨﺔ ﻤﻥ ﺃﺭﻗﺎﻡ ﻭﺤﺭﻭﻑ ‪.‬ﻫﺫﻩ ﻫﻲ ﺍﻹﻋـﺩﺍﺩﺍﺕ‬ ‫ﺍﻻﻓﺘﺭﺍﻀﻴﺔ ﺍﻝﺘﻲ ﻭﺠﺩﺕ ﻝﺘﺴﻬل ﺍﻝﻌﻤﻠﻴﺔ ﻋﻠﻰ ﺍﻝﻤﺴﺘﺨﺩﻤﻴﻥ ﻝﮑﻥ ﺇﻥ ﺒﻘﻴﺕ ﻫﮑﺫﺍ ﻓﺈﻨﻬﺎ ﻗـﺩ‬ ‫ﺘﺅﺩﻱ ﺇﻝﻰ ﻤﺼﺎﺌﺏ ﮑﺒﻴﺭﺓ ﻴﻤﮑﻥ ﺍﻝﺤﺩ ﻤﻨﻬﺎ ﻭﻗـﺩ ﻴﻤﮑـﻥ ﺘﻼﻓﻴﻬـﺎ ﺒﺎﺘﺒـﺎﻉ ﺍﻝﺘﻌﻠﻴﻤـﺎﺕ‬ ‫ﻭﺍﻝﻨﺼﺎﺌﺢ‪.‬‬

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‫‪Wireless Networks‬‬

‫ﻫﺫﻩ ﺒﻌﺽ ﺍﻷﻤﻭﺭ ﺍﻝﺘﻲ ﺴﺘﺴﺎﻋﺩ ﻓﻲ ﺘﻘﻭﻴﺔ ﺃﻤﻥ ﺍﻝـﺸﺒﮑﺎﺕ ﺍﻝﻼﺴـﻠﮑﻴﺔ ﺭﻏـﻡ ﺃﻥ‬ ‫ﺍﻝﺤﺩﻴﺙ ﻋﻥ ﺃﻤﻥ ﺍﻝﺸﺒﮑﺎﺕ ﺃﻤﺭ ﻭﺍﺴﻊ ﺠﺩﹰﺍ ﻭﻻ ﻴﻤﮑﻥ ﺤﺼﺭﻩ ﻓـﻲ ﺩﺭﺱ ﺇﻻ ﺃﻥ ﻭﻀـﻊ‬ ‫ﺍﻝﻨﻘﺎﻁ ﻋﻠﻰ ﺍﻝﺤﺭﻭﻑ ﺃﻤﺭ ﻤﻁﻠﻭﺏ ﻝﻤﻌﺭﻓﺔ ﺃﻫﻡ ﺍﻷﻤﻭﺭ ﺍﻝﺘﻲ ﻴﺠﺏ ﺍﻝﺘﺭﮑﻴﺯ ﻋﻠﻴﻬﺎ ﻝﺘﻘﻠﻴل‬ ‫ﺍﻝﻤﺨﺎﻁﺭ ﺍﻝﺘﻲ ﻗﺩ ﻴﻭﺍﺠﻬﻬﺎ ﺃﻱ ﻤﺴﺅﻭل ﻋﻥ ﺍﻝﺸﺒﮑﺎﺕ‪.‬‬

‫ﻣﻊ ﲤﻨﻴﺎﺗﻨﺎ ﻟﻜﻢ ﺑﺎﻟﺘﻮﻓﻴﻖ ﻭﺍﻟﻨﺠﺎﺡ‬ ‫ﺍﻟﺪﺍﺋﻤﲔ‬ ‫‪42‬‬ ‫تو ا‬

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Wireless Networks

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