Finding a proxy servers address for a new computer - TCP-IP

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Thread: Finding a proxy servers address for a new computer

  1. Finding a proxy servers address for a new computer

    Question: Say I have a bought a new personal computer, and have
    connected it to the local area network at work. The local area network
    uses Ethernet. How would the newly connected computer find the IP
    address of the proxy server?

    Is it something to do with an ICMP broadcast? Any help or links to
    useful resources would be greatly appreciated.

    Thanks.

  2. Re: Finding a proxy servers address for a new computer

    |Question: Say I have a bought a new personal computer, and have
    |connected it to the local area network at work. The local area network
    |uses Ethernet. How would the newly connected computer find the IP
    |address of the proxy server?

    By proxy I take it you mean HTTP proxy and not a gateway. Probably by
    probing the most commonly used HTTP proxy ports: 3128 8080 and maybe
    others.
    --

  3. Re: Finding a proxy servers address for a new computer

    Aaron B wrote:
    > Question: Say I have a bought a new personal computer, and have
    > connected it to the local area network at work. The local area network
    > uses Ethernet. How would the newly connected computer find the IP
    > address of the proxy server?
    >
    > Is it something to do with an ICMP broadcast? Any help or links to
    > useful resources would be greatly appreciated.
    >
    > Thanks.



    Hello
    Your question is unclear. Tell us, for what purpose you are using a proxy
    server. If it is for internet, you can check the proxy server in Internet
    Explorer
    options(assuming windows) , in connections tab of any other computer on LAN.

    --
    Winners dont do different things, they do things differently.

    Madhur Ahuja
    India

    Homepage : http://madhur.netfirms.com
    Email : madhurahujayahoocom






  4. Re: Finding a proxy servers address for a new computer

    aaron100@gmail.com (Aaron B) wrote in message news:<3e83c091.0408260546.2d27f45e@posting.google.com>...
    > Question: Say I have a bought a new personal computer, and have
    > connected it to the local area network at work. The local area network
    > uses Ethernet. How would the newly connected computer find the IP
    > address of the proxy server?
    >
    > Is it something to do with an ICMP broadcast? Any help or links to
    > useful resources would be greatly appreciated.
    >
    > Thanks.


    ICMP, um, no. Though it might be involved in finding your nearest
    routers - google for "icmp redirect".

    I think http://nscsysop.hypermart.net/setproxy.html answers your
    question pretty well. They may be talking about a specific product
    (Novell?) but their comments are generally applicable. I have nothing
    to do with them, the page just turned up in a google search.

    Summary: some browsers (MS?) can pick it up via DHCP, or via the
    network login script (windows or novell networking), if your network
    admins have set either of these appropriately. But if this were the
    case, it would have worked for you by now. More commonly (and my own
    experience verifies this) you ask the guy in the next cube and he
    examines his browser settings and writes it on a sticky.

    Chip C

  5. Re: Finding a proxy servers address for a new computer

    In article <3e83c091.0408260546.2d27f45e@posting.google.com>,
    aaron100@gmail.com (Aaron B) wrote:

    > Question: Say I have a bought a new personal computer, and have
    > connected it to the local area network at work. The local area network
    > uses Ethernet. How would the newly connected computer find the IP
    > address of the proxy server?


    The network administrator should tell you what it is if you need to know
    it.

    If the office network uses DHCP to configure client PC's, this might be
    included in the information sent to the PC, but I don't know how common
    that is. DHCP is mostly used to configure the client IP address, the
    default router, and the DNS server. However, it's an extensible
    protocol, and it may have an option to set the HTTP proxy.

    --
    Barry Margolin, barmar@alum.mit.edu
    Arlington, MA
    *** PLEASE post questions in newsgroups, not directly to me ***

  6. Re: Finding a proxy servers address for a new computer

    aaron100@gmail.com (Aaron B) wrote in message news:<3e83c091.0408260546.2d27f45e@posting.google.com>...
    > Question: Say I have a bought a new personal computer, and have
    > connected it to the local area network at work. The local area network
    > uses Ethernet. How would the newly connected computer find the IP
    > address of the proxy server?
    >
    > Is it something to do with an ICMP broadcast? Any help or links to
    > useful resources would be greatly appreciated.



    It's not a single method, unfortunately. Overall, the process is
    called "Web Proxy Auto Discovery" (Google on that). In most cases the
    relevant data comes back from the DHCP server at the same time the
    workstation gets the other network settings. Not everyone uses DHCP,
    nor do all DHCP servers support the required data strings, so there
    are a couple of alternative methods.

  7. Re: Finding a proxy servers address for a new computer

    AB> How would the newly connected computer find the IP
    AB> address of the proxy server?

    _Which_ proxy server, for _what_ protocol ?

    For proxy _DNS_ servers:

    Computers (strictly: the DNS clients running on those computers) "find"
    the IP addresses of proxy DNS servers by being explicitly told what they
    are, either directly or indirectly via the DHCP lease.




    For proxy _HTTP_ servers:

    Computers (strictly: one particular vendor's web browser running on
    those computers) find proxy _HTTP_ servers using a well-known protocol,
    WPAD, to find a PAC script, that is then run to find the proxy HTTP
    server. In the cases of other web browsers, proxy HTTP servers are
    either "found" by the web browsers being told explicitly where they are,
    or are found by running a PAC script whose location they are explicitly
    told.



    For proxy servers for other protocols:

    Proxy servers for other protocols are, in general, "found" by the
    applications concerned with those protocols being explicitly told where
    they are.

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