Working on a VPN killswitch and playing with UFW. I'm experiencing a putty SSH session freeze when enabling UFW. Port 22 is open and it only freezes the session where the UFW enable command was sent from. Other running sessions continue to work just fine. One interesting thing, the hung session immediately responds after a reboot command is sent from a different session, then it dies as the machine is rebooting. the response is:

sidewyz@ubuntu:~$ sudo ufw enable
Command may disrupt existing ssh connections. Proceed with operation (y\n)? y

freeze is here- only responds with reboot command from other session

Firewall is active and enabled on system startup

only ufw rule is allow ssh nothing in syslog and nothing strange in ufw.log

I can start and stop new sessions normally, it's only the one session that issued the enable command that's frozen.

Using putty to Ubuntu server 18.04 on ESXI 6.5

Any help would be great, I'd like to get my killswitch working ;-)

  • What do you get from sudo ufw status before you enable ufw? Please update the question with the answer. Copy the output of the command and paste it in the question. Then format it as code. – user68186 Nov 26 '20 at 0:11

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