Score:0

Weird ESTABLISHED connections from multiple IP's to my server through ports I already configured my firewall to deny access from

in flag

I have a server running Debian 10 and I use "ufw" as my firewall tool, I used it to open few ports only 80,443,22
I tried to execute "netstat -na" to see if any unauthorized connections to my server and this what I got :
......................
udp________0______0 my_public_ip:45859_____162.159.200.123:123_____ESTABLISHED
udp________0______0 my_public_ip:60435_____162.159.200.1:123_______ESTABLISHED
udp________0______0 my_public_ip:54338_____51.255.197.148:123______ESTABLISHED
udp________0______0 my_public_ip:50250_____176.137.36.37:123_______ESTABLISHED
udp________0______0 my_public_ip:35926_____51.77.79.1:123__________ESTABLISHED
udp________0______0 my_public_ip:38070_____95.81.173.8:123_________ESTABLISHED
udp________0______0 my_public_ip:52411_____212.85.158.10:123_______ESTABLISHED
udp________0______0 my_public_ip:34078_____37.59.63.125:123________ESTABLISHED
udp________0______0 my_public_ip:60702_____51.77.221.70:123________ESTABLISHED
udp________0______0 my_public_ip:46665_____51.15.182.163:123_______ESTABLISHED
......................

Here my "ufw status" :

Status: active

To_________________________Action______From
443________________________ALLOW_______Anywhere
80_________________________ALLOW_______Anywhere
22_________________________ALLOW_______Anywhere
443 (v6)___________________ALLOW_______Anywhere (v6)
80 (v6)____________________ALLOW_______Anywhere (v6)
22 (v6)____________________ALLOW_______Anywhere (v6)

I tried to block connections from these IP's and it didn't work. they still connected. And every time I reboot the server I got different IP's connections but from the same port.

How to fix it, Or netstat info doesn't mean anything.

Score:1
ar flag

udp 0 0 my_public_ip:45859 162.159.200.123:123 ESTABLISHED

Direction is from your machine to 162.159.200.123. It's UDP, so it's connectionless. The state established stems from that your system sent an outgoing packet from the source port to the remote host on port 123, and the firewall notes that fact and allows replies in the opposite direction.

Port 123 is common for NTP. This is not remote systems connecting to you. It's you connecting to remote systems. By default, outgoing traffic is allowed by most firewalls.

You're probably running some ntp implementation that connects to a set of NTP servers to get accurate time.

mangohost

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