Traceroute

Traceroute is a computer program that determines which routers and Internet access via node IP data packets to the requested computer.

Operation

Traceroute sends multiple IP data packets of type ICMP echo request to the target host, starting with a Time to Live (TTL) of 1 The first router to forward the data packet counts the value of the TTL by one down to 0, whereupon he will not pass it, but discards. He sends the ICMP reply type 11: Time exceeded with code 0: Time to live exceeded in transit to the sender. This data package contains the source address, the IP address of your router. This information is recorded by the Traceroute program along with the entire transmission duration. Then the program repeats this step with an increased TTL by 1 to determine in the same way the next router on the path through the network. This is repeated until the destination host or the maximum used by the respective traceroute program of hops has been reached. If the destination host is reached, it sends ICMP -based traceroute ICMP response type ICMP echo reply 0 or Unreachable for UDP -based traceroute Destination Code 3 Port Unreachable.

The sequence of addresses thus collected identifies the path to the destination through the network. The return journey is usually the same, but may have been different in asymmetric routing. In general, three packets are sent to each host. The three values ​​shown in milliseconds give the response time of these three tests again.

The result of traceroute does not always show the actual path. It is affected by firewalls, faulty implementations of the IP stack, network address translation, IP tunnels or choosing a different path in network congestion and other factors.

Under Unix exist on IPv6 -enabled systems next traceroute usually also traceroute6. On Windows Traceroute can be called as tracert.exe. In addition, there since Windows 2000 still pathping actually to review a complete network path is intended, but can also be used as faster Traceroute. The advantage of pathping is that the packages are not sequential, they sent concurrently and shorter waiting times. The disadvantage is that it can not cope with some faulty networks. Under Linux mtr has similar functionality.

Windows traceroute sends ICMP packets by default, Unix traceroute uses UDP packets. Only special programs eg tcptraceroute or LFT Work with TCP packets (Layer Four Traceroute ). All of these traceroute implementations, however, are dependent on the returning ICMP packets. Testing different protocols and ports is useful if a firewall is blocking traceroute. In particular, the use of UDP is often problematic. Some Unix traceroutes can change with the parameter "- I" on ICMP or with " T " on TCP.

Examples

Traceroute on Unix and Linux:

C: \> tracert www.t- online.de Tracing route to www.t- online.de [ 217.6.164.162 ] over a maximum of 30 hops:    1 < 1 ms < 1 ms < 1 ms 137 250 124 250    2 < 1 ms < 1 ms < 1 ms csc72.Net.Uni - Augsburg.DE [ 137.250.90.250 ]    3 < 1 ms < 1 ms < 1 ms ar - augsburg1 - ge3 1.x win.dfn.de [ 188.1.37.137 ]    4 3 ms 3 ms 3 ms cr - Stuttgart1 - po4 2.x win.dfn.de [ 188.1.18.126 ]    5 3 ms 3 ms 3 ms 62,156,138,237    6 6 ms 6 ms 6 ms f eb1.F.DE.net.DTAG.DE [ 62.154.17.138 ]    7 6 ms 6 ms 6 ms rincewind.sfm.t - online.de [ 62.159.199.6 ]    8 6 ms 6 ms 6 ms 217.6.167.198    9 7 ms 6 ms 6 ms 217.6.164.162 Trace complete. Pathping in Windows XP:

C: \ qemu > pathping -p 1-w 1000 -q 1 google.at Tracing route to google.at [ 66.249.93.104 ] over a maximum of 30 hops:    0 cerberus [ 10.10.10.110 ]    1 10.10.10.254    2 80.123.142.xxx    3 62.47.95.239    4 172.19.89.145    5 195.3.66.142    6 195.3.70.37    7 195.3.70.86    8 de - cix10.net.google.com [ 80.81.192.108 ]    9 209.85.249.180   10 209.85.248.182   11 209.85.248.79   12 72.14.233.77   13 66.249.94.46   14 ug -in- f104.google.com [ 66.249.93.104 ] Calculation of statistics takes about 0 seconds ...              Source to Here This Node / Link RTT Lost. / Ges. =% Verl. / Ges. =% Address    0 cerberus [ 10.10.10.110 ]                                  0 /1 = 0 % |    1 2ms 0 /1 = 0 % 0 /1 = 0% 10.10.10.254                                  0 /1 = 0 % |    2 5ms 0 /1 = 0 % 0 /1 = 0% 80.123.142.xxx                                  0 /1 = 0 % |    3 23ms 0 /1 = 0 % 0 /1 = 0% 62.47.95.239                                  0 /1 = 0 % |    4 14ms 0 /1 = 0 % 0 /1 = 0% 172.19.89.145                                  0 /1 = 0 % |    5 14ms 0 /1 = 0 % 0 /1 = 0% 195.3.66.142                                  0 /1 = 0 % |    6 17ms 0 /1 = 0 % 0 /1 = 0% 195.3.70.37                                  0 /1 = 0 % |    7 17ms 0 /1 = 0 % 0 /1 = 0% 195.3.70.86                                  0 /1 = 0 % |    8 26ms 0 /1 = 0 % 0 /1 = 0% de - cix10.net.google.com [ 80.81.192.108 ]                                  0 /1 = 0 % |    9 38ms 0 /1 = 0 % 0 /1 = 0% 209.85.249.180                                  0 /1 = 0 % |   10 34ms 0 /1 = 0 % 0 /1 = 0% 209.85.248.182                                  0 /1 = 0 % |   11 40ms 0 /1 = 0 % 0 /1 = 0% 209.85.248.79                                  0 /1 = 0 % |   12 35ms 0 /1 = 0 % 0 /1 = 0% 72.14.233.77                                  0 /1 = 0 % |   13 51MS 0 /1 = 0 % 0 /1 = 0% 66.249.94.46                                  0 /1 = 0 % |   14 39ms 0 /1 = 0 % 0 /1 = 0% ug -in- f104.google.com [ 66.249.93.104 ] Trace complete. see also

• Geolocation