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MAC address as random input?MAC address as random input?Posted Jul 23, 2012 19:14 UTC (Mon) by BenHutchings (subscriber, #37955)In reply to: MAC address as random input? by Max.Hyre Parent article: Random numbers for embedded devices By default, the local part of the IPv6 address is the MAC address with 16 constant bits in the middle. There is an option to use 'privacy extensions' which means the local part is randomised (sysctl net.ipv6.conf.all.use_tempaddr; Documentation/networking/ip-sysctl.txt).
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MAC address as random input? Posted Jul 25, 2012 18:45 UTC (Wed) by kleptog (subscriber, #1183) [Link]
Note that the default varies by implementation. Various versions of windows default to privacy extensions.
Privacy extensions means your IP changes regularly, usually once a day. For servers you don't want that, but for client PCs the tradeoff is different. If it bugs you you can set the IP address yourself.
Note the link-local address always includes your MAC address, but that address never leaves the LAN, and everyone on your LAN needs your MAC address anyway to talk to you.
MAC address as random input? Posted Jul 26, 2012 12:18 UTC (Thu) by farnz (guest, #17727) [Link] More accurately, it adds an extra IP that changes regularly; you still have the permanent IP that you would have if you didn't enable privacy extensions, but you also have a temporary IP that changes, and that is used in preference to your permanent IP for outgoing connections. The idea is that if you give me your permanent IP, I can connect to you. If you don't, the only IP of yours I know about is your temporary IP, which changes regularly - so while it's fine for the duration of communication you initiated, it's not useful in a few days time.
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