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Vista's TCP/IP Promises and Perils

boyko.at.netqos tips us to a new writeup on Vista's TCP/IP stack, which is called Compound TCP/IP (CTCP). From the article: "...security policy will come from a centralized source. When you get your DHCP lease, your computer will report to the stack what OS you're using, what version level, what patches, what anti-virus software that's active — all that kind of stuff. It will have the ability to restrict your network access if you have a down-level machine... We could see a lot of our customers with much higher WAN network utilization because of this new TCP/IP stack... CTCP can be enabled/disabled from the command prompt but there has been no mention of tuning parameters which leads us to ask the question: How are you supposed to configure this setting in Vista?... What worries us... is that Microsoft is basing this on packet round trip time. The round-trip time from the client-side will have the server processing time in it; but the clients aren't likely going to be the running the CTCP at first. If you have a server-to-server backup running, for example, CTCP may think its part of the round-trip time and it'll throw the delay window through the roof..."

4 of 183 comments (clear)

  1. Article summary by ledow · · Score: 5, Informative

    Article summary:

    We haven't used Vista.
    We haven't tested the features we're talking about.
    We think they're actually probably very good.
    We don't know (and nor does anyone) because we haven't tested them.
    They could be bad.
    They could do nasty stuff to your networks.
    But we don't know because we haven't tested anything.
    Sounds good in theory though.
    And all the MS guys that have ever wrote about it say it works.
    We don't think it'll work perfectly first time.
    But we don't know because we haven't tested anything at all in any way.
    We advise others to test before they make any decision.

    Good article. (That was sarcasm. At least I think it was but I haven't tested it myself yet).

  2. Promising... by Mr_Icon · · Score: 5, Funny

    But, alas, falls short of implementing the "Evil Bit."

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  3. Why build it into the stack? by Kadin2048 · · Score: 5, Informative

    I don't get it. If you're just going to be querying the OS for information about its configuration (antivirus, patch state, version level, etc.) why don't you just implement it at a higher level? I don't see any reason to bury this sort of stuff down in the network stack. It could just as easily run as an application-level service rather than being built in down on the transport level. (And in fact I know of systems which do this sort of thing running as userspace tools.)

    The goal here seems to just be a way to allow corporate networks like WANs to restrict access based on the version of Windows that's running and the security software being implemented on the client. Setting aside how a rootkit would just fake the responses (and I don't believe for a second that there won't be rootkits for Vista once it gets mainstream), why does this have to be in the network stack? It could be easily implemented as part of the higher-level networking services like WINS or Active Directory, as a requirement before the user is allowed access to particular network resources.

    This whole concept seems rather flawed, unless there's some large part of it that I'm missing, and it just seems like it's going to require other OSes to rewrite their perfectly good TCP/IP stacks in order to inter-operate with Windows networks. Maybe that's the whole point?

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  4. Asking the Google for more info... by NullProg · · Score: 5, Informative

    I discover NAC/NAP. Network Admission Control and Network Access Protection. While the idea is noble, its going to be costly (for customers) to implement in mixed networks. They also don't discuss non PC network clients (Printers, Scanners, hand held etc). Even worse (see below), your going to have to pay for a 3rd party network stack for Windows 2000.

    White paper here: http://download.microsoft.com/download/d/0/8/d08df 717-d752-4fa2-a77a-ab29f0b29266/NAC-NAP_Whitepaper .pdf

    Interesting chat transcript here: http://www.microsoft.com/technet/community/chats/t rans/network/06_0914_tn_network.mspx

    From the transcript:

    Q: NAP seems to fulfill the pre-admission health/integrity check very well. Can customers use the same NAP infrastructure to support post-admission NAC? e.g. with NAP today I can check a desktop PC is healthy when it joins, but what about 24 hours later?
    A: Post-admission enforcement depends on the enforcement mechanism you're using. For instance, health will be re-evaluated when a client attempts to renew their IP address when using DHCP as the enforcement mechanism. For IPSec, it will happen when health certs expire. For 802.1x, it will happen when re-authentication occurs. For VPN, it will happen when clients reconnect. Any health change on the client will trigger re-evaluation of the health state, too.

    Q: What is the likelihood of a NAP agent for Windows 2000 clients in the network?
    A: We are not planning to implement a Windows 2000 NAP client. However, we are licensing our protocols to 3rd party companies so that they can offer NAP clients on Windows 2000 (and other OS's like Mac, Linux, etc.)


    Enjoy,

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