trace route & analyse path

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TRACE ROUTE & ANALYSE PATH

A network diagnostic tool

Originally written by Van Jacobson

Whether routing problems exist on the network?

3 primary objectives of the TRACEROUTE tool

The entire path the packet travels

through

The name & identity of routers &

devices in your path

Network Latency : The time taken to

send and receive data to each devices in

the network

` TTL ???

Time To Live Time …. Is it measured in

seconds ??? Hopes…

Hops are nothing but the computers, routers, or any devices that comes in between the source and the destination.

?What if there was no TTL at all !!!

But the router which discards the

packet will inform the original sender

that the TTL value has exceeded.!

ICMP TTL exceeded

messages

But how does Traceroute uses TTL

exceeded message to find out

routers/hops in between?

traceroute to google's publicly available DNS server(8.8.8.8)

http://3.bp.blogspot.com/-1T1fvKKzpkc/UeP7bWAqReI/AAAAAAAAAYM/BbiRepHTV1g/s1600/tr1.png

root@workstation:~# tcpdump -n '(icmp or udp)' –vvv 12:13:06.585187 IP (tos 0x0, ttl 1, id 37285, offset 0, flags [none], proto UDP (17),

length 60)

192.168.0.102.43143 > 8.8.8.8.33434: [bad udp cksum 0xd157 -> 0x0e59!] UDP, length 32

12:13:06.585218 IP (tos 0x0, ttl 1, id 37286, offset 0, flags [none], proto UDP (17), length 60)

192.168.0.102.38682 > 8.8.8.8.33435: [bad udp cksum 0xd157 -> 0x1fc5!] UDP, length 32


192.168.0.102.48381 > 8.8.8.8.33436: [bad udp cksum 0xd157 -> 0xf9e0!] UDP, length 32


192.168.0.102.57602 > 8.8.8.8.33437: [bad udp cksum 0xd157 -> 0xd5da!] UDP, length 32


192.168.0.102.39195 > 8.8.8.8.33438: [bad udp cksum 0xd157 -> 0x1dc1!] UDP, length 32


This UDP packet will contain the following

things.

My Source Address (Which is my IP address)

Destination address (Which is 8.8.8.8)

And A destination UDP port number which is

invalid. Means the traceroute utility will send

packet to a UDP port in the range of 33434 to

33534, Which is normally unused.

My Source address will make a packet

with destination ip address of 8.8.8.8 and

a destination port number between 33434

to 33534. And the important thing it

does it to make the TTL Value 1

On receiving this TTL Time exceeded

message, my traceroute program will

come to know the source address

and other details about the first hop

(Which is my gateway server.)

Again sends a UDP packet with

different port number and TTL value

2… and so on….

192.168.0.1 > 192.168.0.102: ICMP time exceeded in-transit, length 68

IP (tos 0x0, ttl 1, id 37285, offset 0, flags [none], proto UDP (17), length 60)




IP (tos 0x0, id 37288, offset 0, flags [none], proto UDP (17), length 60)



Why 3 UDP Packets with TTL value 1???

root@workstation:~# tcpdump -n '(icmp or udp)' –vvv 12:13:06.585187 IP (tos 0x0, ttl 1, id 37285, offset 0, flags [none], proto UDP (17),

length 60)

192.168.0.102.43143 > 8.8.8.8.33434: [bad udp cksum 0xd157 -> 0x0e59!] UDP, length 32


192.168.0.102.38682 > 8.8.8.8.33435: [bad udp cksum 0xd157 -> 0x1fc5!] UDP, length 32


192.168.0.102.48381 > 8.8.8.8.33436: [bad udp cksum 0xd157 -> 0xf9e0!] UDP, length 32


192.168.0.102.57602 > 8.8.8.8.33437: [bad udp cksum 0xd157 -> 0xd5da!] UDP, length 32


192.168.0.102.39195 > 8.8.8.8.33438: [bad udp cksum 0xd157 -> 0x1dc1!] UDP, length 32


Why 3 UDP Packets with TTL value 1???

RTP : Round Trip Time

How the Traceroute program will come to

know that the destination is reached ??

“ICMP Port/Destination UNREACHABLE “

INSERT INTO tbl_users(user_unq_id,user_course_id,user_fullname,user_username,user_password,user_mobile,user_email,user_status,user_previlage) VALUES ('123','1','Saumya','sam','c2Ft','918547057028','[email protected]','0','user')

8.8.8.8 > 192.168.0.102: ICMP 8.8.8.8

udp port 33458 unreachable, length 68 IP (tos 0x80, ttl 2, id 37309, offset 0, flags [none],

proto UDP (17), length 60) 8.8.8.8 > 192.168.0.102: ICMP 8.8.8.8


proto UDP (17), length 60) 8.8.8.8 > 192.168.0.102: ICMP 8.8.8.8


proto UDP (17), length 60)

Traceroute program will come to know that our destination has reached

Different types of Traceroute program

UDP TracerouteICMP tracerouteTCP Traceroute

trace route & analyse path

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