port-being blocked

Discussion in 'Cisco' started by cconnell_1, Jun 28, 2005.

  1. cconnell_1

    cconnell_1 Guest

    Does anyone know a utility to show you at what point (perhaps a router
    hop) a port is being blocked? A customer of ours has said they have
    opened their firewall to allow port 11000, I cant see any drops on our
    router/firewall, but would like to trace somehow at which point or
    router/firewall is dropping the packet. We cannot get to their network
    on this port.
    cconnell_1, Jun 28, 2005
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  2. cconnell_1

    RobO Guest


    Are you able to do a port scan on the specific IP address to see if the
    port is really open (possibly the ISP has blocked the port)?

    If its a TCP port there is a Unix based tcp traceroute tool called
    "tcptraceroute" available at
    You can specify destination ports.

    I dont know of any Windows tools that do this, anybody else know?

    Hope this helps,

    RobO, Jun 28, 2005
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  3. Unless they've configured "no ip unreachable", the router should send an
    ICMP Unreachable -- Administratively Prohibited when it drops a packet
    due to a filter.
    Barry Margolin, Jun 29, 2005
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