iptables vs nftables: Vergleich und Migrationsanleitung

# Aktuelle iptables-Regeln anzeigen
sudo iptables -L -n -v
sudo iptables -L -n -v --line-numbers

# Grundlegende Regeln
sudo iptables -A INPUT -p tcp --dport 22 -j ACCEPT
sudo iptables -A INPUT -p tcp --dport 80 -j ACCEPT
sudo iptables -A INPUT -p tcp --dport 443 -j ACCEPT
sudo iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
sudo iptables -P INPUT DROP

# Regeln speichern
sudo iptables-save > /etc/iptables/rules.v4

# nftables installieren
sudo apt install nftables -y
sudo systemctl enable nftables
sudo systemctl start nftables

# Aktuelle Regeln anzeigen
sudo nft list ruleset

sudo nano /etc/nftables.conf

#!/usr/sbin/nft -f

# Bestehende Regeln löschen
flush ruleset

# inet-Familie deckt IPv4 und IPv6 ab
table inet filter {
    chain input {
        type filter hook input priority 0; policy drop;
        
        # Loopback-Schnittstelle erlauben
        iif lo accept
        
        # Bestehende Verbindungen erlauben
        ct state established,related accept
        
        # ICMP (Ping)
        ip protocol icmp accept
        ip6 nexthdr icmpv6 accept
        
        # SSH
        tcp dport 22 accept
        
        # HTTP/HTTPS
        tcp dport { 80, 443 } accept
        
        # Protokollieren und ablehnen
        log prefix "nftables-drop: " drop
    }
    
    chain forward {
        type filter hook forward priority 0; policy drop;
    }
    
    chain output {
        type filter hook output priority 0; policy accept;
    }
}

# Konfiguration anwenden
sudo nft -f /etc/nftables.conf

# Syntax prüfen (ohne Anwenden)
sudo nft -c -f /etc/nftables.conf

# iptables NAT
sudo iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
sudo iptables -t nat -A PREROUTING -p tcp --dport 80 -j DNAT --to-destination 192.168.1.10:80

# nftables NAT-Äquivalent
table ip nat {
    chain prerouting {
        type nat hook prerouting priority -100;
        tcp dport 80 dnat to 192.168.1.10:80
        tcp dport 443 dnat to 192.168.1.10:443
    }
    
    chain postrouting {
        type nat hook postrouting priority 100;
        oif eth0 masquerade
    }
}

# nftables Rate Limiting
chain input {
    tcp dport 22 limit rate 3/minute burst 5 packets accept
    tcp dport 22 drop
}

# nftables Sets (eingebaut)
table inet filter {
    set blocked_ips {
        type ipv4_addr
        elements = { 1.2.3.4, 5.6.7.8 }
    }
    
    chain input {
        type filter hook input priority 0; policy drop;
        ip saddr @blocked_ips drop
        tcp dport 22 accept
    }
}

# Konvertierungstool installieren
sudo apt install iptables-nftables-compat -y

# Bestehende iptables-Regeln konvertieren
iptables-save | iptables-restore-translate -f /etc/nftables.conf
ip6tables-save | ip6tables-restore-translate >> /etc/nftables.conf

# 1. Bestehende iptables-Regeln sichern
sudo iptables-save > /root/iptables-backup.txt

# 2. nftables-Konfiguration erstellen
sudo nano /etc/nftables.conf

# 3. Konfiguration testen
sudo nft -c -f /etc/nftables.conf

# 4. nftables aktivieren
sudo systemctl enable nftables
sudo nft -f /etc/nftables.conf

# 5. iptables deaktivieren
sudo systemctl disable iptables
sudo systemctl stop iptables

# 6. Regeln überprüfen
sudo nft list ruleset