I want to limit source port range in my ubuntu machine upto 20000 , that means no Application should be able to use port higher than that.I have this command in mind

iptables -A OUTPUT -p tcp --sport 20001:65535 --dport 20001:65535 -j DROP

But , wouldn't this drop all packets rather than limiting ? I need a configuration such that I can still browse the web , just not through port 20001 to 65535 . No incoming or outgoing through this ports.


Edit net.ipv4.ip_local_port_range in /etc/sysctl.conf with:

sudo nano /etc/sysctl.conf

or any other editor of your choice and add or change:

# Allowed local port range
net.ipv4.ip_local_port_range = 1024 20000

Restart your network.

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