traceroute: last hop ip different with dest address in output.

[ktaog6]

Hi,

when i use traceroute module, the last address not my address in output, does it mean the address can't reach ? And Hop 3 to Hop 21 means 4~20 not response ?

Example:

Python 3.8.5 (default, Sep 22 2020, 23:34:13) [GCC 4.8.5 20150623 (Red Hat 4.8.5-36)] on linux Type "help", "copyright", "credits" or "license" for more information.

from icmplib import * traceroute("192.168.46.25") [<Hop 1 [193.22.152.1]>, <Hop 2 [172.16.0.11]>, <Hop 3 [192.168.101.42]>, <Hop 21 [38.142.238.113]>]

[ValentinBELYN]

Hi @ktaog6,

Yes, if the last address is not the one you want to reach, there are two possible causes:

• If you can ping this address (with the built-in ping function or your system's ping command), more than 30 hops (default) may be needed to reach it. You can try increasing the max_hops parameter of the traceroute function. It should work. Example: traceroute('192.168.46.25', max_hops=64)
• Otherwise, if you cannot reach this address even with the ping command, either the remote machine is off or its firewall is blocking ICMP requests.

For your second deduction, you are also right. Hosts 4 through 20 did not respond. Some routers, like these, are configured not to send ICMP Time Exceeded messages for security reasons.

I hope I've helped you.

[ktaog6]

ok, thanks.