Number of simultaneous nmap processes/scans

In the first phase of the scan, GVM lauches several openvas processes in parallel:


root 3565 0.0 0.1 178208 16832 ? SN 13:35 0:00 openvas: testing 141.42.206.244 (/var/lib/openvas/plugins/nmap.nasl)
root 3566 0.0 0.1 178208 16844 ? SN 13:35 0:00 openvas: testing 141.42.207.37 (/var/lib/openvas/plugins/nmap.nasl)
root 3567 0.0 0.1 178208 16844 ? SN 13:35 0:00 openvas: testing 141.42.206.176 (/var/lib/openvas/plugins/nmap.nasl)

Each of those launches a single nmap process:

root       3589  2.5  0.0  58572 13756 ?        SN   13:35   0:00 nmap -n -Pn -oG /tmp/nmap-141.42.206.244-1568646203 -sT -sU -p T:1-65535,U:7,9,17,19,49,53,67-69,80,88,111,120,123,135-139,158,161-162,177,427,443,445,497,500,514-515,518,520,593,623,626,631,996-999,1022-1023,1025-1030,1433-1434,1645-1646,1701,1718-1719,1812-1813,1900,2000,2048-2049,2222-2223,3283,3456,3703,4444,4500,5000,5060,5353,5632,9200,10000,17185,20031,30718,31337,32768-32769,32771,32815,33281,49152-49154,49156,49181-49182,49185-49186,49188,49190-49194,49200-49201 -T4 141.42.206.244

[root@netz-secscan] /root# ps auxwww|egrep nmap | wc -l
61

In total, I counted 30 openvas processes, each launching one nmap process.

Where/how can I reduce this parallelism?

Just change your task when you creating one:

https://docs.greenbone.net/GSM-Manual/gos-6/en/scanning.html?highlight=nvt#creating-a-task

Keywords: Maximum concurrently executed NVTs per host
Maximum concurrently scanned hosts

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No, that’s not helping. It’s not the NVTs, but the initial nmap scan (which is running at much higher concurrency).