Traceroute

traceroute is a TCP/IP utility which allows the user to determine the route packets take to reach a particular host. traceroute works by increasing the "time to live" value of each successive packet sent. The first packet has a TTL value of one, the second two, and so on. When a packet passes through a host, the host decrements the TTL value by one and forwards the packet to the next host. When a packet with a TTL of one reaches a host, the host discards the packet and sends an ICMP time exceeded (type 11) packet to the sender. The traceroute utility uses these returning packets to produce a list of hosts that the packets have traversed en route to the destination.

On modern Unix and Linux-based operating systems, the traceroute utility by default uses UDP datagrams with a destination port number starting at 33434. The traceroute utility usually has an option to specify use of ICMP echo request (type 8) instead. The Windows utility uses ICMP echo request, better known as ping packets. Some firewalls on the path being investigated may block UDP probes but allow the ICMP echo request traffic to pass through. There is also traceroute implementation using TCP packets, such as tcptraceroute

In Microsoft Windows, traceroute is named tracert. A new utility, pathping, was introduced with Windows NT, combining ping and traceroute functionality.

Contents

1 Example 2 Origins 3 Uses 4 External links

Example

Estonia to the United States. 195.80.96.219 (kauge.aso.ee) to 130.94.122.199 (larousse.wikipedia.org).

1   kauge.aso.ee
2   et-gw.aso.ee
3   kjj-bb2-fe-0-1-4.ee.estpak .ee
4   noe-bb2-ge-0-0-0-1.ee.estpak.ee
5   s-b3-pos0-3.telia.net
6   s-bb1-pos1-2-0.telia.net
7   adm-bb1-pos1-1-0.telia.net
8   adm-b1-pos2-0.telia.net
9   p4-1-2-0.r00.amstnl02.nl.bb.verio.net
10  p4-0-3-0.r01.amstnl02.nl.bb.verio.net
11  p4-0-1-0.r80.nwrknj01.us.bb.verio.net
12  p4-0-3-0.r00.nwrknj01.us.bb.verio.net
13  p16-0-1-1.r20.mlpsca01.us.bb.verio.net
14  xe-1-2-0.r21.mlpsca01.us.bb.verio.net
15  xe-0-2-0.r21.snjsca04.us.bb.verio.net
16  p64-0-0-0.r21.lsanca01.us.bb.verio.net
17  p16-3-0-0.r01.sndgca01.us.bb.verio.net
18  ge-1-2.a03.sndgca01.us.da.verio.net
19  larousse.wikipedia.org

Origins

The traceroute manpage states that the original traceroute program was written by Van Jacobson from a suggestion by Steve Deering, with particularly cogent suggestions or fixes from C. Philip Wood, Tim Seaver and Ken Adelman.

Uses

Traceroute can also be used for network troubleshooting. It, by showing a list of the routers, allows the user to identify faulty routers or router loops that may create problems for data to be transfered.

External links

• RFC792
• traceroute.org - (updated monthly) list of online traceroutes

---