Do NAT-routers block UDP packets?

Discussion in 'Network Routers' started by Router Man, Jul 20, 2007.

  1. Router Man

    Router Man Guest

    Given a standard residential NAT router that has all ports closed or
    blocked, and does not have a DMZ configured - would such a router
    pass, or block, unsolicited UDP packets to PC's connected to it's LAN
    ports?
     
    Router Man, Jul 20, 2007
    #1
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  2. Router Man

    Lenny_Nero Guest

    Router Man said
    Say this line to youeself again ...and then think what it will do with
    unsolicited traffic.

    L.
     
    Lenny_Nero, Jul 21, 2007
    #2
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  3. Router Man

    Router Man Guest

    Just answer the question.

    Is there something *different* about UDP packets (vs TCP) that would
    allow a router to pass them even if the owner thinks the router is
    properly set up to block all unsolicited packets?

    Should be an easy question for this newsgroup to answer...
     
    Router Man, Jul 21, 2007
    #3
  4. Router Man

    Nethawg Guest

    You stated all ports are Blocked or Closed so NOTHING is getting through.
    Restate your question.
     
    Nethawg, Jul 21, 2007
    #4
  5. Router Man

    Router Man Guest

    In another newsgroup, person A mentioned seeing this:
     
    Router Man, Jul 22, 2007
    #5
  6. Router Man

    Router Man Guest

    It's a simple question people.

    Do symetric (One-to-Many) NAT-Routers block/drop all unsolicited
    external/in-bound packets, regardless of the type of packet?

    Or are unsolicited UDP packets allowed to get through?
     
    Router Man, Jul 23, 2007
    #6
  7. Router Man

    Router Man Guest

    Sorry.

    I thought there were router "Experts" here who could answer a simple
    question.
     
    Router Man, Jul 26, 2007
    #7
  8. I'm not an expert, I'm going to take NA classes at the local JC in the
    fall, so - while this is interesting - I apologize if my answers aren't
    applicable.

    http://help.soft32.com/questions/31/NAT-(Network-Address-Translation)

    With symmetric NAT all requests from the same internal IP address and
    port to a specific destination IP address and port are mapped to a
    unique external source IP address and port. If the same internal host
    sends a packet with the same source address and port to a different
    destination, a different mapping is used. Only an external host that
    receives a packet can send a UDP packet back to the internal host.

    http://en.wikipedia.org/wiki/Network_address_translation

    Symmetric NAT

    * Each request from the same internal IP address and port to a
    specific destination IP address and port is mapped to a unique external
    source IP address and port. If the same internal host sends a packet
    even with the same source address and port but to a different
    destination, a different mapping is used.

    * Only an external host that receives a packet from an internal
    host can send a packet back.

    Mike
     
    Mike Scirocco, Jul 28, 2007
    #8
  9. Router Man

    rcp Guest

    Well, I guess it depends on the router. I have used Netgear, Linksys, and
    D-Link. If memory serves, they generally block all ports (UDP and TCP),
    allow specific ports to be forwarded to specific systems and allow one
    to specify UDP, TCP, or both.

    Bob
     
    rcp, Sep 3, 2007
    #9
  10. Router Man

    catwalker63 Guest

    This is Usenet. There is no test to take to be allowed to read or post
    to a Usenet public newsgroup. Your question was answered. The ports are
    blocked and the packets are dropped. The difference between UDP and TCP
    is packet size and error correction. Not sneakiness.
     
    catwalker63, Sep 4, 2007
    #10
  11. Router Man

    catwalker63 Guest

     
    catwalker63, Sep 4, 2007
    #11
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