fping results 'packet loss'

Kaiden · 11-01-2022, 02:47 PM

Code:

x.x.x.x : [0], 84 bytes, 63.8 ms (63.8 avg, 0% loss)
x.x.x.x : [1], 84 bytes, 62.2 ms (63.0 avg, 0% loss)
x.x.x.x : [2], 84 bytes, 66.2 ms (64.1 avg, 0% loss)
x.x.x.x : [3], 84 bytes, 66.6 ms (64.7 avg, 0% loss)
x.x.x.x : [4], 84 bytes, 67.7 ms (65.3 avg, 2% loss)
x.x.x.x : [5], 84 bytes, 67.8 ms (65.7 avg, 3% loss)

How is packet loss determined in fping? How do we receive 2% or 3% packet loss in a single ping?
Is packet loss accumulative or is it based on each individual ping?

camorri · 11-01-2022, 03:42 PM

Quote:

fping results 'packet loss' - How is it determined?

The simple answer is, for every ping sent, the program is expecting 1 back. Lost pings are counted.

This program is used to ping multiple ip addresses with one command entered.

Have a read through this page -->https://www.tecmint.com/ping-multipl...s-using-fping/

and this page -->https://blog.eldernode.com/work-with-fping-in-linux/

for examples of how to use fping. You will see its design is to use it in scripts for sys admins with large networks to monitor.

Kaiden · 11-04-2022, 10:21 AM

Quote:

Originally Posted by camorri

The simple answer is, for every ping sent, the program is expecting 1 back. Lost pings are counted.

This program is used to ping multiple ip addresses with one command entered.

Have a read through this page -->https://www.tecmint.com/ping-multipl...s-using-fping/

and this page -->https://blog.eldernode.com/work-with-fping-in-linux/

for examples of how to use fping. You will see its design is to use it in scripts for sys admins with large networks to monitor.

Hi, thank you for the information and links as well. I get the idea as to how packet loss is determined when pings are missed, but what is confusing me is that when running a

Code:

fping -c [seconds] [ip range]

command, fping shows packet loss in each and every ping rather than the summary of pings at the end results. This leaves me to believe that fping may be sending more than 1 ICMP packet to its target per actual ping .. .. I am trying to figure out how a single ping can have lets say 3% loss, unless there is more than 1 ping being executed in that ping. I can understand a 0% or 100% loss but how would I get results like 3% in just a single ICMP request? My original post shows how the output of fping -c is displayed and you'll notice that fping is reporting the packet loss for every icmp request where I 'thought' it would be either a reachable (0% loss) or unreachable (100% loss) deal.

camorri · 11-04-2022, 12:25 PM

I can not answer you question on how the program calculates the % of loss. That would have to be in the doc, or a question to the developer.

I usually use nmap when looking at network problems.

I have this package installed

Quote:

fping-5.0-x86_64-1_SBo

on Slackware. The output I get is similar to yours, low % loss on 1 or 2 pings.

I read through the README file in the doc directory. This tool was written at Stanford University to check their network. You can contact them at https://fping.org/

chrism01 · 11-06-2022, 10:01 PM

I think the answer is hinted at here https://linux.die.net/man/8/fping

Quote:

In the default mode, if a target replies, it is noted and removed from the list of targets to check; if a target does not respond within a certain time limit and/or retry limit ..

and

Quote:

-rn

Retry limit (default 3). This is the number of times an attempt at pinging a target will be made, not including the first try.

although I agree they could have made it more explicit.

You could check by using eg wireshark/tcpdump.