Can not access Certain sites

Discussion in 'Cisco' started by Jeremy McMasters, Sep 22, 2004.

  1. I am curious to whether anyone on this board has ever ran into a problem
    where if you have a .0 or a .255 as an ip address (last octet) that you
    can't access websites like www.ebay.com or www.microsoft.com. I have a /21
    that I have handling otu ip address's to subscribers using Cisco Network
    Registrar. I am wondering if there is something I need to do on Layer 3 or
    this needs to be escalated to my upstream-provider
    Jeremy McMasters, Sep 22, 2004
    #1
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  2. Jeremy McMasters

    Rod Dorman Guest

    In article <>,
    Jeremy McMasters <> wrote:
    > I am curious to whether anyone on this board has ever ran into a
    >problem where if you have a .0 or a .255 as an ip address (last
    >octet) that you can't access websites like www.ebay.com or
    >www.microsoft.com. I have a /21 that I have handling otu ip
    >address's to subscribers using Cisco Network Registrar. I am
    >wondering if there is something I need to do on Layer 3 or this needs
    >to be escalated to my upstream-provider


    I've got a SMC7004VWBR at home that has an issue with .0 or .255 when
    I enabled the more aggressive firewall features. It would start
    complaining about "smurf" attacks even though it knew the netmask and
    should have realized the IP address wasn't the broadcast address.

    It didn't affect just a couple of websites though, it was unusable
    until I disabled the anti-DOS option.

    --
    -- Rod --
    rodd(at)polylogics(dot)com
    Rod Dorman, Sep 22, 2004
    #2
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  3. Jeremy McMasters

    S. Gione Guest

    ..0 is reserved (network address)
    ..255 is reserved - broadcast.

    "Jeremy McMasters" <> wrote in message
    news:...
    > I am curious to whether anyone on this board has ever ran into a

    problem
    > where if you have a .0 or a .255 as an ip address (last octet) that you
    > can't access websites like www.ebay.com or www.microsoft.com. I have a

    /21
    > that I have handling otu ip address's to subscribers using Cisco Network
    > Registrar. I am wondering if there is something I need to do on Layer 3

    or
    > this needs to be escalated to my upstream-provider
    >
    >
    S. Gione, Sep 22, 2004
    #3
  4. Jeremy McMasters

    S. Gione Guest

    Cancel my prior statement ... I did not initially notice the 21 bit network
    notation.

    Network would include zeros in the 3 low-order bits of the 3rd octet and
    broadcast 1s in those bit positions.

    This is assuming the network mask is set for 248 in the third octet.

    "S. Gione" <> wrote in message
    news:O6k4d.16769$...
    > .0 is reserved (network address)
    > .255 is reserved - broadcast.
    >
    > "Jeremy McMasters" <> wrote in message
    > news:...
    > > I am curious to whether anyone on this board has ever ran into a

    > problem
    > > where if you have a .0 or a .255 as an ip address (last octet) that you
    > > can't access websites like www.ebay.com or www.microsoft.com. I have a

    > /21
    > > that I have handling otu ip address's to subscribers using Cisco Network
    > > Registrar. I am wondering if there is something I need to do on Layer 3

    > or
    > > this needs to be escalated to my upstream-provider
    > >
    > >

    >
    >
    S. Gione, Sep 22, 2004
    #4
  5. In article <O6k4d.16769$>,
    S. Gione <> wrote:
    :.0 is reserved (network address)
    :.255 is reserved - broadcast.

    Incorrect. The all-zero "host" portion of an IP address is reserved,
    and the all-ones "host" portion of an IP address is reserved, but
    even in the old Class A/B/C/D days, that didn't automatically mean
    that .0 and .255 were reserved.

    For example, the class B address 132.133.0.0 is reserved and
    132.133.255.255 would be reserved too for Class B, but (say)
    132.133.18.255 would not be reserved. For Class B, the "network"
    portion of the address is "132.133" and the host portion is the
    remaining 16 bits, and the address is reserved only if all 16 of those
    remaining bits are pure 0's or pure 1's.

    Of course, with CIDR, pretty much any IP can end up being reserved
    as being either the network base or the broadcast for some sufficiently
    small network.

    There is an RFC for using /31's on point-to-point links, that removes
    the reserved status from the two addresses.
    --
    I've been working on a kernel
    All the livelong night.
    I've been working on a kernel
    And it still won't work quite right. -- J. Benson & J. Doll
    Walter Roberson, Sep 22, 2004
    #5
  6. What I am thinking, of what Rod wrote about his firewall filtering out .0
    and .255 ip address's even though I have another /21 that can access the
    same site I will have to rule this out. Its an odd occurance and I am
    actually quiet stumped on this. lets say I have 207.255.136.0 /21, this
    block with any ip address .0 or .255 is blocked at microsoft or ebay. But I
    have 24.197.56.0 /21 that can go to any site with out incident. All my
    reverse's are in order. .0 and .255 should be viable /21 ip addresses as
    long as it is not the beginning and ending ip address of the /21.

    Jeremy





    "Jeremy McMasters" <> wrote in message
    news:...
    > I am curious to whether anyone on this board has ever ran into a

    problem
    > where if you have a .0 or a .255 as an ip address (last octet) that you
    > can't access websites like www.ebay.com or www.microsoft.com. I have a

    /21
    > that I have handling otu ip address's to subscribers using Cisco Network
    > Registrar. I am wondering if there is something I need to do on Layer 3

    or
    > this needs to be escalated to my upstream-provider
    >
    >
    Jeremy McMasters, Sep 22, 2004
    #6
  7. Jeremy McMasters

    S. Gione Guest

    Just my opinion, but I don't think that either of these addresses should be
    used. For a 21-bit mask, they are both network addresses (last 11 bits
    zero).

    I don't know where in your (or outside on the route) it's happening, but it
    appears that some classful constraints are being applied. This might be why
    the 207 fails (class C in classful) and the 24.197.56.0 gets thru (because
    it would be valid for a mask of 20 bits or less).

    "Jeremy McMasters" <> wrote in message
    news:...
    > What I am thinking, of what Rod wrote about his firewall filtering out .0
    > and .255 ip address's even though I have another /21 that can access the
    > same site I will have to rule this out. Its an odd occurance and I am
    > actually quiet stumped on this. lets say I have 207.255.136.0 /21, this
    > block with any ip address .0 or .255 is blocked at microsoft or ebay. But

    I
    > have 24.197.56.0 /21 that can go to any site with out incident. All my
    > reverse's are in order. .0 and .255 should be viable /21 ip addresses as
    > long as it is not the beginning and ending ip address of the /21.
    >
    > Jeremy
    >
    >
    >
    >
    >
    > "Jeremy McMasters" <> wrote in message
    > news:...
    > > I am curious to whether anyone on this board has ever ran into a

    > problem
    > > where if you have a .0 or a .255 as an ip address (last octet) that you
    > > can't access websites like www.ebay.com or www.microsoft.com. I have a

    > /21
    > > that I have handling otu ip address's to subscribers using Cisco Network
    > > Registrar. I am wondering if there is something I need to do on Layer 3

    > or
    > > this needs to be escalated to my upstream-provider
    > >
    > >

    >
    >
    S. Gione, Sep 23, 2004
    #7
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