[CentOS] Find out which process consumed Network bandwidth

Tue Sep 14 00:18:51 UTC 2021
Charles Polisher <chas at chasmo.org>

On Mon, 6 Sept 2021 at 14:24, Anand Buddhdev <anandb at ripe.net>

>> On 06/09/2021 19:35, Kaushal Shriyan wrote:
>> Hi Kaushal,
>>> I am running CentOS Linux release 7.9.2009 (Core). Is there a way to find
>>> out which process consumed network bandwidth during a specific time period?
>>> For example, the Nginx process consumed how much network traffic on Sept
>>> 01, 2021.
>> As far as I know, such accounting isn't done in a standard CentOS
>> system, so there's no way to determine such information about a past event


While you probably can't recover such information for past events,
going forward, iptables can help you figure this out. Putting an IPtables
rule in the OUTPUT table prior to ACCEPTing the packets can help, e.g.:

     iptables -A OUTPUT -p tcp -m owner --uid-owner nginx -j ACCEPT

because now "iptables -L" will display a count of the packets that matched
each rule and the number of bytes. By comparing with the total packets
and bytes for a given time period, you can work out the share for nginx.
You can also estimate packet and byte counts by IP and port using this
method. You could run an hourly cronjob to log the stats.

See "man iptables-extensions" and "man iptables". I don't know how this
works with firewall-cmd, but I imagine firewalld "just" manages iptables?

Good luck!