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Let's say I traceroute to address A:

Here's what the start of the traceroute looks like:

$ traceroute -d
traceroute to (, 64 hops max, 52 byte packets
 1 (  4.799 ms  12.566 ms  0.766 ms
 2 (  8.915 ms  7.186 ms  8.070 ms
 3 (  8.810 ms  9.118 ms  14.246 ms
 4 (  7.578 ms  7.420 ms  7.702 ms

But then I try traceroute to address B: and I get just * * * :

 $ traceroute -d
 traceroute to (, 64 hops max, 52 byte packets
 1  * * *
 2  * * *

This is despite the fact that address B is on the way to address A.

How can A be reachable on the way to B, but not reachable directly?


This is the traceroute version I am using:

$ traceroute -v
Version 1.4a12+Darwin
Usage: traceroute [-adDeFInrSvx] [-A as_server] [-f first_ttl] [-g gateway] [-i iface]
[-M first_ttl] [-m max_ttl] [-p port] [-P proto] [-q nqueries] [-s src_addr]
[-t tos] [-w waittime] [-z pausemsecs] host [packetlen]
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up vote 2 down vote accepted

It will depend on the device that is your default gateway / first hop, I expect. Use traceroute -I and use ICMP instead of default UDP. Then it will probably work.

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