ping - Tracert behaviour explanation
2014-02
blended
Sorry if my question is trivial, I tried to tracert to an ip address, and after first 12 hops I got request timed out for the rest, until reach a maximum of 30 hops.
I assume that the machine is up and running since the list is refreshed (in the list , even though ping gives request time out). I know basic things from firewalls and gateways and how they can turn ping reply's off etc.
Question: what is the following behavior , if the host is not reachable why the TTL are increasing ? is this a packet loop for some reason ? Any chance the real location of the server is somewhere else and is passing through myriad proxies and thus 30+ hops?
Tracert will keep going until it reaches 30 hop counts. Your screenshot shows that it entered the blocked area where ICMP request packets are ignored.
You might see another situation where some packets in the middle are timedout, and it replies after that. It depends on the device that receives the ICMP request packet from your client. Tracert command increases TTL by one unit to reach further device on the path, if that device blocks or doesn't answer your ICMP Request, you got the timedout message. Next step, your tracert command will try another router behind the previous one. At each steps, it totally depends on the destination router.
David Schwartz
The TTL is increasing because the traceroute tool is trying to reach machines further away. There might be three machines in a row that don't permit traceroute replies and then one that does. Unless it checks, traceroute doesn't know.
Robert Atkins
Possible Duplicate:
Mac OS X traceroute not even reaching router gateway
I am on M1 Cable (residential) broadband in Singapore.
I have an intermittent problem routing to some sites from my MacBook Pro—often Google-related sites (arduino.googlecode.com and ajax.googleapis.com right now, but sometimes even gmail.com.) This prevents StackExchange chat from working, for instance. Funny thing is, my iPad can route to those sites and they're on the same wireless network! I can ping the sites, but not traceroute to them which I find odd.
That I can get through via the iPad implies the problem is with the MBP. In any case, calling M1 support is... not helpful.
I get the same behaviour when I bypass the Airport Express entirely and plug the MBP directly into the cable modem. Can anybody explain a) how this is even possible and b) how to fix it?
mella:~ ratkins$ ping ajax.googleapis.com
PING googleapis.l.google.com (209.85.132.95): 56 data bytes
64 bytes from 209.85.132.95: icmp_seq=0 ttl=50 time=11.488 ms
64 bytes from 209.85.132.95: icmp_seq=1 ttl=53 time=13.012 ms
64 bytes from 209.85.132.95: icmp_seq=2 ttl=53 time=13.048 ms
^C
--- googleapis.l.google.com ping statistics ---
3 packets transmitted, 3 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 11.488/12.516/13.048/0.727 ms
mella:~ ratkins$ traceroute ajax.googleapis.com
traceroute to googleapis.l.google.com (209.85.132.95), 64 hops max, 52 byte packets
traceroute: sendto: No route to host
1 traceroute: wrote googleapis.l.google.com 52 chars, ret=-1
*traceroute: sendto: No route to host
traceroute: wrote googleapis.l.google.com 52 chars, ret=-1
^C
mella:~ ratkins$
The traceroute from the iPad goes (and I'm copying this by hand):
10.0.1.1
119.56.34.1
172.20.8.222
172.31.253.11
202.65.245.1
202.65.245.142
209.85.243.156
72.14.233.145
209.85.132.82
From the MBP, I can't traceroute to any of the IPs from 172.20.8.222 onwards.
RedGrittyBrick
Firstly, the traceroute: sendto: No route to host message is your primary clue. Your MacBook Pro's network configuration isn't fully functional. Perhaps the MacBook is configured with some static settings that overide the settings that are obtainable by DHCP from your cable broadband modem or router?
Secondly MacBooks and iPads run different operating systems. It is possible that this has some bearing on the problem. Either in the way these devices pick up wireless settings or in the way tracert/traceroute work (normally they use ICMP protocol but some variants use TCP - it is possible that ICMP is blocked at some router/firewall)
On the Macbook Pro, can you get it to display it's network settings - chiefly default gateway and DNS servers? E.g. ifconfig -a
If you can see the equivalent informatio on the iPad - look for differences.
Robert Atkins
Turns out this was the answer (tl;dr, nuke Peerguardian from orbit.)