From: "Perry E. Metzger" <perry@imsi.com> Eric Hughes says:
Perry advocates IPSP as an almost-panacea for Internet security. I disagree.
Well, no; it doesn't fix things like mail for which the data needs to be protected but not the link. In the case of email, there's the same discrepancy I pointed out earlier -- the machine or filesystem boundary is not the same as the trust boundary. This will happen for email as well as more live and online communications needs. TIA is sort of a short term hack people are using to get around having to have their administrators manage SLIP or PPP properly; I suspect this difficulty will vanish with time. I agree with you that this particular example may be short lived, but you appear to have ignored the more fundamental point I was making. Namely, the existence of communications proxies which _change_ the level of abstraction will be with us forever. The TIA unix end switches from TCP-to-the-world to IP-to-the-PC. That's a level switch. IP is ultimately designed to be a proxy protocol that will work over anything -- stuff like TIA simply gets around temporary mental difficulties among providers in seeing things that way...< I'm not saying that IP proxies won't exist. What I am saying is that other forms of proxying will also exist. Not all policies will be able to be enforced at the IP level. As soon as you want security policy to apply to non-IP abstractions, IPSP is no longer primary, even if it's still involved. Firewall policies are a prime example of security policy enforced at the TCP and UDP levels, with access control by port number. External firewalls, a class that includes packet laundries, web proxies, and IRC anonymizers, will not for the most part operate at the IP level. It's certain that IP security will greatly increase the overall security of the Internet. I'm not advocating its removal but rather the acknowledgement that higher (and lower) level abstractions will require their own cryptography. Eric