Uses the IPv6 protocol hop limit field to elicit an ICMPv6 TIME_EXCEEDED response from each gateway along the path to some host.

      traceroute6 [-dIlnNrvU] [-f firsthop] [-g gateway] [-m hoplimit]
         [-p port] [-q probes] [-s src] [-w waittime] target [datalen]

   -d          Debug mode.

   -f firsthop Specify how many hops to skip in trace.

   -g gateway  Specify intermediate gateway (traceroute6 uses routing header).

   -I          Use ICMP6 ECHO instead of UDP datagrams.

   -l          Print both host hostnames and numeric addresses.
               Normally traceroute6 prints only hostnames if -n is not specified,
               and only numeric addresses if -n is specified.

   -m hoplimit Specify maximum hoplimit, up to 255.  The default is 30 hops.

   -n          Do not resolve numeric address to hostname.

   -N          Use a packet with no upper layer header for the probes, instead of UDP datagrams.

   -p port     Set UDP port number to port.

   -q probes   Set the number of probe per hop count to probes.

   -r          Bypass the normal routing tables and send directly to a host on an attached network.
               If the host is not on a directly-connected network, an error is returned.
               This option corresponds to the SO_DONTROUTE socket option; it can be used to ping a local host
               through an interface that has no route through it
               (e.g., after the interface was dropped by a routing daemon).

   -s src      Src specifies the source IPv6 address to be used.

   -U          Use UDP datagrams for the probes.  This is the default.

   -v          Be verbose.

   -w waittime Specify the delay time between probes.

The only mandatory parameter is the destination host name or IPv6 address. The default probe datagram carries 12 bytes of pay- load, in addition to the IPv6 header. The size of the payload can be specified by giving a length (in bytes) after the destination host name.

This program prints the route to the given destination and the round-trip time to each gateway, in the same manner as tracer- oute. Here is a list of possible annotations after the round-trip time for each gateway:

   !N      Destination Unreachable - No Route to Host.

   !P      Destination Unreachable - Administratively Prohibited.

   !S      Destination Unreachable - Not a Neighbour.

   !A      Destination Unreachable - Address Unreachable.

   !       This is printed if the hop limit is <= 1 on a port unreachable message.  This means that the packet got to the
           destination, but that the reply had a hop limit that was just large enough to allow it to get back to the source
           of the traceroute6.  This was more interesting in the IPv4 case, where some IP stack bugs could be identified by
           this behaviour.

Return Values

The traceroute6 utility will exit with 0 on success, and non-zero on errors.

“2. The tendency to worry about things that cannot be changed or corrected.” ~ Marcus Tullius Cicero (The Six Mistakes of Man)

Related macOS commands

netstat - Show network status.
traceroute - Trace Route to Host
ping - Test a network connection.

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