blog:Network_Attributes_of_your_computer_1

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# Network Attributes of your computer␍␊### Contents    ␍␊␍␊1 MAC Address␍␊1.1 Linux␍␊1.2 Windows␍␊1.3 Mac OS␍␊2 802.11 "nickname"␍␊2.1 Linux␍␊2.2 Mac OS␍␊2.3 Windows␍␊3 DHCP Properties␍␊3.1 Linux␍␊3.2 Windows␍␊3.3 Mac OS␍␊␍␊# MAC Address␍␊Every 802.x network card (wireless, ethernet, token ring) has a unique 48 bit identifier known as a MAC address. This address is burned into the EEPROM on the card, and oftentimes is used by networking equipment to track users as they come and go, frequently associating MAC address to hotel or dorm room #, credit card number, login info, etc. This means hopping on a network that has authenticated your hardware before and expecting to be anonymous this time around is pure idiocy.In fact, even most consumer wireless gear will record the MAC addresses of all computers that have ever issued DHCP requests to them, and these logs usually cannot be purged, even by the owner! When you combine this with the fact that most Cable/DSL service providers will also record your MAC address and bind it to your billing information, and the fact that some of them don't even seem to wait for a court order to turn your info over, it becomes apparent that your MAC address essentially is your name. This isn't even counting the possibility of databases maintained by the major laptop manufactures.One particularly useful hack I have discovered is that if you change your MAC address, cable and DSL providers typically will give you a new IP address via DHCP. This can be useful if you are a heavy user of P2P networks, since changing your IP regularly can help keep you off the RIAA/MPAA's "big fish" watchlists, since without access to the ISPs internal databases they will be unable to correlate your identity across IP address changes. That is, unless you keep the same "nickname" in whatever P2P app you use...Thus, changing your MAC address is highly desirable for a number of reasons. However, note that you really only have to concern yourself with your MAC address if you do not wish the local network administrator to be able to identify you. MAC addresses do not cross router boundaries, so anything outside of your LAN will never see it. If your adversary is not internal to the LAN or cannot trace your FIXME IP address back to the LAN, don't worry about your MAC.␍␊Here are the commands to change your MAC for the three major platforms:␍␊LinuxIn Linux, you just need to issue two commands, and then re-run dhcp or reconfigure the interface. ␍␊This works for both wired and wireless cards.    ␍␊```␍␊[root@machine ~/dir]# ifconfig eth0 down ␍␊[root@machine ~/dir]# ifconfig eth0 hw ether de:ad:be:ef:f0:0d␍␊[root@machine ~/dir]# ifconfig eth0 up␍␊```␍␊You can also use the tool 'macchanger' which is available in most of the repositories. It also allows you to set a random mac address.    ␍␊```␍␊[root@machine ~/dir]# ifconfig eth0 down ␍␊[root@machine ~/dir]# macchanger -r eth0␍␊[root@machine ~/dir]# ifconfig eth0 upUse --help ␍␊```␍␊to view many more options available.␍␊WindowsUnder Windows, however, things are a bit more involved.. There are a few ways to do it. One involves wading through your registry, and will not be discussed here. If you're lucky, you might be able to do it right from control panel. If this is not an option, you can try this ntsecurity.nu utility or this utility.␍␊Mac OSIn Mac OS, for some reason it is easy to change the MAC address of your wired interface. One of the following two commands should work:    ␍␊```␍␊[user@machine ~/dir]$  sudo ifconfig en0 ether aa:bb:cc:dd:ee:ff␍␊[user@machine ~/dir]$  sudo ifconfig en0 lladdr 00:01:02:03:04:05␍␊```␍␊However, to change the MAC of a wireless interface, you will need to patch your kernel, and then recompile it.Some OS X users have informed me that USB wireless adapters often allow you to change the MAC address via the command line just like a wired interface. The one most commonly mentioned is the Belkin F5D7050.I should also note that many routers will allow you to clone or specify a MAC address from their web interface...␍␊802.11 "nickname"The 802.11 Nickname field is a little-known feature of the wireless spec that sends your hostname to the AP. This is obviously bad.␍␊Linux   [root@machine ~/dir]#  iwconfig ath0 nickname "Fucko The Clown"Mac OSUnder Mac OS, your Computer name is your hostname. You can change it with sudo hostname -s "Fucko The Clown". However, your hostname resets every time you restart your computer. To permanently change your hostname, go to SystemPreferences-Sharing. From here you can change your computer name. Your default hostname will then be Example.local␍␊WindowsI think your only option is to choose an obscure machine name. If you wish to change your hostname, you can either edit these registry keys or run the NewSID utility␍␊DHCP PropertiesUpon obtaining an IP address, your DHCP client will sometimes send information about you in DHCP requests. In many cases, this includes your hostname and possibly your MAC address, but can include your operating system and DHCP version, which can potentially be very damaging to your anonymity set on your local network. Once again, much like MAC address, if you are unconcerned about your local network discovering your identity, then you probably needn't worry too much about this. However, in many cases it is necessary to obscure this information.Also, as part of the DHCP standard, all operating systems will provide their most recent IP address to the DHCP server. Usually this is harmless, since it is typically just an internal IP address, but if you use your laptop to DHCP directly to your ISP, it is possible it may then hand this IP to an open access point you associate to. If you are changing your MAC address to minimize risk for P2P activity, you may want to wipe previous IP leases on your router machine every time you obtain a new lease. Typically router devices have a 'release DHCP' button somewhere on the web interface. If you need to change these settings on your computer itself, follow the appropriate instructions below:␍␊# Linux␍␊Unfortunately under Linux, the details of DHCP client properties vary from distribution to distribution. In the general case for dhclient, the values are read from /etc/dhclient-interface.conf, but this is typically created at runtime. In Fedora, for example, only the hostname is transmitted, and this value is read from /etc/sysconfig/networks/ifcfg-ethN where N is the relevant interface number.Gentoo (and likely any other distro that uses dhcpcd), however, will transmit the entire OS and kernel version. One contributor suggested changing your /etc/init.d/net.eth0 (or equivalent) file to include     ␍␊```␍␊VID=`fortune -o|head -c 30|tr "\"'\n" ' ' 2>/dev/null`␍␊/sbin/dhcpcd -i ${VID} ${dhcpcd_IFACE} ${IFACE}Previous IP/␍␊```␍␊Lease information is typically found under /var/lib/dhcp/. ␍␊Blowing these files away between interface restarts (/sbin/ifdown ethN ; [change mac addr] ; [change hostname] ; rm /var/lib/dhcp/* ; /sbin/ifup ethN) should do the trick.␍␊␉␉ ␍␊# Windows␍␊Windows sends your MAC address and an OS and version string (though the version is something nonsensical, like "MSFT 5.0", which means it might not map to exact Windows versions, but some DHCP implementation version). Unfortunately, Windows also transmits hostname. I don't believe there is any way to stop this, but you should not have picked a hostname that easily identifies you anyways. Unfortunately, it can be used to correlate successive connections, which makes it easier to track you down eventually. It seems as though the utility NewSID can be used to change your hostname on the fly. Alternatively, you can edit a few registry keys.To kill a previous lease, usually all you have to do is go to Control Panel->Network Connections and right click on the interface, and go to Disable, and then Enable. This will blow away any previous lease state and IP address information. If you prefer the command line, ipconfig /release followed by ipconfig /renew does the trick.␍␊␍␊# Mac OS␍␊Mac OS sends just the MAC address and hostname, but you should be aware that it also has some option codes that can serve to identify the OS type as well. Again, to change the hostname, issue something like `sudo hostname -s` "Fucko The Clown", and don't forget to change your FIXME mac address.As far as leasing/IP information, go to System Preferences->Network and select Network Port Configurations under Show:. Then, click the checkbox next to the relevant connection to disable the interface, and then click it again to enable it, and the lease will be blown away and renewed. From the command line,` sudo ipconfig` set en0 BOOTP followed by sudo ipconfig set en0 DHCP will essentially the same thing (of course, substitute the appropriate interface name for en0).If you want to be absolutely sure you have set everything properly, you can download Ethereal to monitor your network traffic. Set the filter line to bootp while a capture is running. This will display only dhcp requests and responses, which you can then inspect for information to make sure everything is OK. @title="Network Attributes of your computer 1"  @lang="en"  @keywords="matrix,security,internet_security,freedom"  @reply="how_to_exit_the_matrix" 

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