On Fri, 03 Jan 2014 20:52:25 -0500, Owen DeLong <owen@delong.com> wrote:
Not entirely true, actually… If you’re willing to work hard enough at it, most hosts can be “encouraged” to renew early.
Short of commandline access, no there isn't. (crashing or otherwise triggering a reboot, isn't a "renew"; that's a full broadcast restart) And RENEW isn't at issue as that's a unicast request directly with the original DHCP server. Simply turning up your own instance will do nothing there. (attempting to impersonate the real server isn't what were talking about.) For IPv6, you can become a/the router for a segment with the origination of a single packet. Instantly. That's something you can never do with DHCPv4.
Well… Sure, 15 years after DHCP attacks first started being a serious problem… I doubt it will take anywhere near 15 years for RA guard on by default to be the norm in switches, etc.
It'll **NEVER** be a default because it breaks too many clueless people's networks. Just like, surprise, DHCP "guard" isn't on by default in any gear I'm aware of.