You can see the default in this case is to deny any incoming traffic (ingress), like listening for http traffic on port 8000. On the other hand, it allows outgoing traffic (egress) required, for example, to query the software repositories and update the packages as well as installing new packages.
$ sudo ufw allow 80 <== allow http access $ sudo ufw deny 25 <== deny smtp access You can check out the /etc/services file to find the connections between port numbers and service names. UFW to block countries. GitHub Gist: instantly share code, notes, and snippets. Similarly, use sudo ufw delete deny 22 for “deny” rules. More advanced rules Use port ranges. To allow or deny a range of ports, for example ports 2000 to 2010, use the colon notation as shown below. When specifying multiple port, you also have to give the protocol (tcp or udp): sudo ufw allow 2000:2010/tcp sudo ufw allow 2000:2010/udp % sudo ufw deny 21. Or you can also block access to Telnet and SSH ports for extra security for your system if you don’t use those ports: % sudo ufw deny 22 % sudo ufw deny 23. It’s exactly the same command(s), you are simply replacing the allow argument with a deny argument for ufw to understand what you are telling it to do. May 09, 2019 · Changing the order of a few rules might help if this is the case. Allow rules must be entered before deny rules since ufw always looks for the first match when parsing your list for security reasons. Deleting a pair of rules and then adding them back by typing the sudo ufw default allow line first should fix this problem. You might wish to If you want to deny access to a certain port then you can use the following format: sudo ufw deny "Port/Protocol" For example, you can deny access to port 80 by running the following command: sudo ufw deny 80/tcp Allow Port Range. You can also add port ranges into the rules.
UFW - Community Help Wiki
How to Set Up a Firewall with UFW on Ubuntu 18.04 | Linuxize Feb 15, 2019
Jan 24, 2020
UFW will deny all incoming connections after you turn it on. So the first thing you should do is to allow SSH access for the server if you like to manage the system remotely. The command "ufw allow sshport" allow access by SSH, replace SSHPORT with the port of the SSH service, the default SSH port is 22. How to fix the Docker and UFW security flaw - TechRepublic Jan 18, 2018 Linux firewall basics with ufw | Network World $ sudo ufw allow 80 <== allow http access $ sudo ufw deny 25 <== deny smtp access You can check out the /etc/services file to find the connections between port numbers and service names. How to deny all incoming ports except SSH port 22 on May 26, 2020