Jan 03, 2010
Upon sudo ufw disable followed by sudo ufw enable, and even though the ssh connection itself remains fine, the resulting iptables rule set seems to have forgotten the association with that particular connection and therefore classifies any incoming packets as invalid. Somehow the connection tracking table has become confused and the packet is Security - Firewall | Server documentation | Ubuntu Developed to ease iptables firewall configuration, ufw provides a user-friendly way to create an IPv4 or IPv6 host-based firewall. ufw by default is initially disabled. From the ufw man page: “ufw is not intended to provide complete firewall functionality via its command interface, but instead provides an easy way to add or remove simple rules. Ubuntu 18.04でUFWを使用してファイアウォールを設定する方法 UbuntuサーバーでIPv6が有効になっている場合、UFWがIPv4に加えてIPv6のファイアウォールルールを管理するようにIPv6をサポートするように構成されていることを確認します。 これを行うには、 `+ nano +`またはお好みのエディターでUFW設定を開きます。 Ubuntu Allow Port Through Firewall – Linux Hint
Aug 03, 2015
Rules that match both IPv4 and IPv6 addresses apply to both IP versions. For example, when IPv6 is enabled, the following rule will allow access to port 22 for both IPv4 and IPv6 traffic: ufw allow 22 IPv6 over IPv4 tunnels and 6to4 are supported by using the 'ipv6' protocol ('41').
Developed to ease iptables firewall configuration, ufw provides a user-friendly way to create an IPv4 or IPv6 host-based firewall. ufw by default is initially disabled. From the ufw man page: “ufw is not intended to provide complete firewall functionality via its command interface, but instead provides an easy way to add or remove simple rules.
Firewalling Ubuntu with UFW for IPv4 + IPv6 | HackerTarget.com Sep 20, 2012 Disable / Turn Off Firewall in Ubuntu Linux Server - nixCraft