セットアップ

nftables

$ sudo nft list ruleset
$ sudo nft -c -f /etc/nftables.conf
$ sudo systemctl restart nftables

• /etc/nftables.conf

#!/usr/sbin/nft -f

flush ruleset

table inet filter {
    chain input {
        type filter hook input priority filter;
        policy drop;

        iif lo accept

        ct state established,related accept

        ct state invalid drop

        # SSH
        tcp dport 22 accept

        # ICMP
        ip protocol icmp accept
        meta l4proto ipv6-icmp accept

        # mDNS
        ip daddr 224.0.0.251 udp dport 5353 accept
        ip6 daddr ff02::fb udp dport 5353 accept
    }
    chain forward {
        type filter hook forward priority filter;
        policy drop;
    }
    chain output {
        type filter hook output priority filter;
        policy accept;
    }
}

ユーザをgroupに追加

ツール

$ sudo update-alternatives --config editor
$ sudo update-alternatives --config vi

TERM

sudo apt install ncurses-term