Traceroute which port

Use the traceroute command to display a hop-by-hop path through an IP network from the Catalyst series switch to a specific destination host. For each host in the processed path, the initial TTL for each host and the destination UDP port number for each packet sent are incremented by one. The traceroute command uses the TTL field in the IP header to cause routers and servers to generate specific return messages. The traceroute facility determines the address of the first hop by examining the source address field of the ICMP time-exceeded message.

The first router decrements the TTL field by 1 and sends the datagram to the next router. The second router sees a TTL value of 1, discards the datagram, and returns the time-exceeded message to the source. This process continues until the TTL is incremented to a value large enough for the datagram to reach the destination host or until the maximum TTL is reached. Edited by Admin February 16, at AM.

Top Rated Answers. Step 2 is repeated for up to three probes or as many times as requested in an extended traceroute command output. For each of the probes sent, you receive a "TTL exceeded" message, which is used to build a step-by-step path to the destination host. TTL is incremented, and this cycle repeats with incremental destination port numbers, if the ICMP "time exceeded" message is received. You can also get one of these messages: An ICMP type 3, code 3 "destination unreachable," "port unreachable" message, which indicates that a host has been reached.

A "host unreachable," "net unreachable," "maximum TTL exceeded," or a "timeout" type of message, which means that the probe is resent. All Answers. I have seen that number sarah mentioned, but this page shows the udp range as List of TCP and UDP port numbers - Wikipedia, the free encyclopedia Also, this interesting forum response What is the range of ports that is usually used in the traceroute command? Frank and Kev, I'm not sure of the range myself.

The link below has a very interesting discussion. The range mentioned is to Thanks Kev. R1 show ip access-lists Extended IP access list 10 deny icmp any any port-unreachable 5 matches 20 permit ip any any 28 matches R1 traceroute Tracing the route to Then a TTL of 2 - which brings it to the second router. TTL is increased until the destination is reached. The set of routers found along the way is the traced route.

After googling I found out that is the port that is used as the base port for traceroute. Sign up to join this community. The best answers are voted up and rise to the top. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Learn more. What is the range of ports that is usually used in the traceroute command? Ask Question. Asked 10 years ago. Active 7 years, 2 months ago. Viewed 38k times. Can you help us improve?

Resolved my issue. Clear instructions. Easy to follow. No jargon. Pictures helped. Didn't match my screen. Incorrect instructions.