Hello community, first time writing here so let me know if i am missing something.
Running openvas9 + nmap 6.47, when doing network scan against full ip-range (nmap options used: nmap -n -Pn -sS -sU -p -defeat-rst-ratelimit -T3 ), i have noticed that nmap time increase starting from ~ 30 seconds to get a response to 100 sec then 300 sec …600…1200 …1800 and in the end get back to 40 seconds. CPU load during this time was ~97%. I also have checked the syslog for errors like “could not open socket” but none was found.
Question: What could be the reason that nmap port scanning time was increasing? Is it only related to CPU or there are other reasons ?
Thanks for your help.