wireless networking - Can two devices with the same MAC address be on the same network?

What happens if there is a device already connected to a wifi network, and subsequently another device tries to join the wifi network using the exact same MAC address as the original?

Answer

A MAC address is supposed to be unique. If someone sabotages that then two devices on the network will claim to be the same unique NIC. That simply does not work.

Just how it breaks depends on the card and possibly on the driver.

Imagine two people in the same building. Both claiming to be employee number 1.
The left employee #1 shouts 'may I have some coffee?'
Someone fetches coffee and shouts 'Coffee for employee #1 is ready'.
That person now gets two replies, one 'thanks!' and 'Hey, I did not order coffee'.

And just which of the Employee #1's answers first might depend on how busy that person is, adding some more chaos to it.

So briefly: things break.

Comments

Use Google instead of Bing with Windows 10 search

I want to use Google Chrome and Google search instead of Bing when I search in Windows 10. Google Chrome is launched when I click on web, but it's Bing search. (My default search engine on Google and Edge is http://www.google.com ) I haven't found how to configure that. Someone can help me ? Answer There is no way to change the default in Cortana itself but you can redirect it in Chrome. You said that it opens the results in the Chrome browser but it used Bing search right? There's a Chrome extension now that will redirect Bing to Google, DuckDuckGo, or Yahoo , whichever you prefer. More information on that in the second link.

linux - Using an index to make grep faster?

I find myself grepping the same codebase over and over. While it works great, each command takes about 10 seconds, so I am thinking about ways to make it faster. So can grep use some sort of index? I understand an index probably won't help for complicated regexps, but I use mostly very simple patters. Does an indexer exist for this case? EDIT: I know about ctags and the like, but I would like to do full-text search. Answer what about cscope , does this match your shoes? Allows searching code for: all references to a symbol global definitions functions called by a function functions calling a function text string regular expression pattern a file files including a file

How do I transmit a single hexadecimal value serial data in PuTTY using an Alt code?

I am trying to sent a specific hexadecimal value across a serial COM port using PuTTY. Specifically, I want to send the hex codes 9C, B6, FC, and 8B. I have looked up the Alt codes for these and they are 156, 182, 252, and 139 respectively. However, whenever I input the Alt codes, a preceding hex value of C2 is sent before 9C, B6, and 8B so the values that are sent are C2 9C, C2 B6, and C2 8B. The value for FC is changed to C3 FC. Why are these values being placed before the hex value and why is FC being changed altogether? To me, it seems like there is a problem internally converting the Alt code to hex. Is there a way to directly input hex values without using Alt codes in PuTTY? Answer What you're seeing is just ordinary text character set conversion. As far as PuTTY is concerned, you are typing (and reading) text , not raw binary data, therefore it has to convert the text to bytes in whatever configured character set before sending it over the wire. In other words, when y...

linux - CentOs 7.1 - Install Tomcat 8

I am using this tutorial as a setup reference to getting a Tomcat 8 running on CentOs 7.1 , but after typing: [root@localhost tomcat]# sudo systemctl start tomcat I get the error: Job for tomcat.service failed. See 'systemctl status tomcat.service' and 'journalctl -xn' for details. systemctl status tomcat.service prints the following: [root@localhost tomcat]# systemctl status tomcat.service tomcat.service - Apache Tomcat Web Application Container Loaded: loaded (/etc/systemd/system/tomcat.service; disabled) Active: failed (Result: exit-code) since Wed 2015-11-25 16:54:33 CET; 1min 19s ago Process: 45873 ExecStart=/opt/tomcat/bin/startup.sh (code=exited, status=203/EXEC) Nov 25 16:54:33 localhost.localdomain systemd[1]: Starting Apache Tomcat Web Application Container... Nov 25 16:54:33 localhost.localdomain systemd[1]: tomcat.service: control process exited, code=exited status=203 Nov 25 16:54:33 localhost.localdomain systemd[1]: Failed to start Apache Tomcat Web App...

Notes

Search This Blog