Hi, I am new witness, my witness name is @exnihilo-witness.
I have setup my ssh connection to my server and I have changed my ssh port from 22 to xxxxx in the /etc/ssh/sshd_config.
If I follow these commands
sudo apt-get update
sudo ufw default allow outgoing
sudo ufw default deny incoming
sudo ufw allow ssh
sudo ufw enable

I understand that I will enable ssh on port 22.
So instead, I must do
sudo ufw allow xxxxx/ssh.

My question is how my server communicate with the blockchain?
If I do that, will I miss some blocks?
Does the blockchain communicate with my server by ssh on port xxxxx?
It is not possible, how blockchain will know that I have chosen the xxxxx port?

I hope that you understand my point.
In summary, after setting my firewall, I am afraid to deny the treatment of blocks which is the aim of my server and my witness purpose...
Thank you in advance for your help.