DIY your Wifi AP

1. -Maker-
DIY your Tools
cmj
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2. Disclaimer
ALL CONTENT, WHETHER EXPRESS OR IMPLIED, ARE
OPEN INFORMATION. AUTHOR IN THE LEGAL IS
IRRESPONSIBLE FOR YOU.
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3. • Ba a maker, you can
• Learn more what you need
• Enjoy more what you like
• Understand more what you used
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4. Mission - Wifi AP
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5. • I want to design a popular WiFi AP
• Everyone want to access
• Everyone like to access
• Also, I’m happy everyone access my Wifi AP
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6. Design Flow
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7. 7
I want access WiFi

8. 8
I want access WiFi
Your Wifi AP

9. 9
I want access WiFi
Your Wifi AP
Expose Your Device - hostapd

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I want access WiFi
Your Wifi AP
Expose Your Device - hostapd
Assign A IP address - dnsmasq

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I want access WiFi
Your Wifi AP
Expose Your Device - hostapd
Assign A IP address - dnsmasq
Access WLAN - iptable

12. • hostapd
• A userspace daemon for wireless AP
• dnsmasq
• Lightweight DNS / DHCP server
• iptable
• Redirect WiFi packet into WLAN
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13. So Easy ~
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14. • Now we have a basic WiFi AP
• But not sweet enough~
• Who ?
• Why ??
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15. • Now we have a basic WiFi AP
• But not sweet enough~
• Who ?
• Why ?
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16. • If possible
• Everyone on the World is my custom…
• But only the 100m at most, limit by
• frequency band
• radio power
• … etc
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17. • If possible
• Everyone on the World is my custom…
• But only the 100m at most, limit by
• frequency band
• radio power
• … etc
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18. • If possible
• I want only one (of course, mine) WiFi AP
• But WiFI AP is located on everywhere
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19. • If possible
• I want only one (of course, mine) WiFi AP
• But WiFI AP is located on everywhere
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20. So …
The Trivial solution is Best solution
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21. If it looks like a duck, sounds
like a duck, and walks like a
duck, then it probably is a duck
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22. • In real scenario
• School, the total scope is larger than 100m
• You DO NOT want to repeat login.
• Did you realize that you switch to other AP
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23. WiFI Roaming
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24. • Limitation
• Same SSID
• Same Authentication method
• Same Password
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25. • But the real flow are
1. Client send probe request (with SSID)
2. Server response
3. Client authentication
4. Server check and pass the authentication
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26. • But the real flow are
1. Client send probe request (with SSID)
2. Server response
3. Client authentication
4. Server check and pass the authentication
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27. You are the Super Star
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28. • Be the popular, what can we get?
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29. You No Pain I No Gain
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30. You No Pain I No Gain
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31. Who get the router, they own the network!
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32. • Every packets through router
• From, To and Data
• Name, address, and everything you talk on the
network.
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34. Thanks for your attention ~
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