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Old 03-02-2016, 10:34 AM   #1
postcd
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Why is traceroute failing at 172.16.7.2


I tried to traceroute from my home PC to my server which is located on another continent and it timed out. Also i was unable to use that server as my web browser proxy, it timeouts.

But i also tried traceroute to google IP and it worked.

My question is what is the cause and why it timeouted at IP 172.16.7.2?

screenshot:
https://s20.postimg.org/3tif0ko3x/tr..._server_ip.gif

Thank you
 
Old 03-02-2016, 10:51 AM   #2
lazydog
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RFC1918

That IP Address is non-rotatable over the internet.
 
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Old 03-02-2016, 06:05 PM   #3
amiba
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Smile its not timing out at 172.16.7.2

The IP is a private IP of your provider and you have not the problem that it is timing out. What you see is that there is not any information about the IP of the point in the ethernet where your packet is dieing. But it could be that if you wait long enough, it will find the way. Some how it could be that your connection is blocked somewhere in the net or from your provider, by not giving permission to take that answer back in.

If there more than 30 points between, traceroute will stop searching.
Could it be that in your area google is not allowed?

best regards

Andreas
 
Old 03-03-2016, 03:10 AM   #4
postcd
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Lightbulb

Quote:
Originally Posted by amiba View Post
Could it be that in your area google is not allowed?
google IP 8.8.8.8 "never" timeout

Quote:
Originally Posted by amiba View Post
wait long enough, it will find the way.
indeed on the hop 22 there was no longer "timeout". It is IP 23.92.82.6
next hops are ok (no timeout)
What it means in regards to discover where is the issue?
Update: i did another traceroute, but this time all timeouted after IP 172.16.7.2 (last one is no 30)

Quote:
Originally Posted by amiba View Post
somewhere in the net or from your provider, by not giving permission to take that answer back in.
Any way please to discover where?

Last edited by postcd; 03-04-2016 at 03:24 AM.
 
Old 03-03-2016, 08:25 AM   #5
amiba
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Sorry did not read precise your problem

I think that your problem is the way back to you.

Traceroute might find the other Server but to get a communication working you must be allowed to be answered and if traceroute ist going true, you need to understand how traceroute is working. It sends the parcel out with a short value for (don't know how it is named - hops) so first one hop, the unit that is reached after one hop will answer, that the parcel is canceled because of its hop limit. Next you send out them with the limit of hops set to two .... until 30. If some of them get stars it is most that the station that has canceled the parcel is not allowed to send you an answer. But if you get through to the endpoint, this tells you that there is a way to it. Mostly if you can't get a connection working to that point, there is no way back to you as maybe your firewall is blocking it or the firewall of the Server is blocking it. Do you get any other connetion to this server.
 
Old 03-03-2016, 09:01 AM   #6
TB0ne
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Quote:
Originally Posted by postcd View Post
google IP 8.8.8.8 "never" timeout

indeed on the hop 22 there was no longer "timeout". It is IP 23.92.82.6 next hops are ok (no timeout) What it means in regards to discover where is the issue? Any way please to discover where?
You could do basic research on how traceroute works, and learn, if you tried.

Traceroute is based on ICMP or UDP packets. It effectively pings each router on the path between you and the target. It increases TTL for each subsequent packet it sends, expecting that as each packet is sent with an increased TTL from the last, the next router in the path will return an error code.

If the next hop isn't responding, it's probably specifically blocking ICMP/UDP messages. Ping'ing your remote target works, because the routers between you and it are just passing the ICMP/UDP packets through to it rather than responding to them, as they do with a traceroute. Again, try reading a man page, such as "man traceroute"...pay particular attention to the methods you can use, such as I and T, instead of the default of UDP.
 
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