Thursday, December 13, 2018

netstat *:* udp sockets

netstat -an tells me I am listening to all the udp.

Active Internet connections (including servers)
Proto Recv-Q Send-Q Local Address Foreign Address (state)
udp 0 0 *.* *.*
udp 0 0 127.0.0.1.53 *.*
udp 0 0 *.* *.*
udp 0 0 *.5353 *.*
udp 0 0 *.* *.*

What are those *.* sockets doing? How can you listen to all the ports?

According to fstat, two belong to dhclient and one to chrome.

root dhclient 55241 3* internet dgram udp *:0
root dhclient 55241 5* internet dgram udp *:0
tedu chrome 52839 107* internet dgram udp *:0

Although now they are printed as *:0. How do such sockets work?

And, perhaps more directly, how would I block this in pf.conf?

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