Snippets

Ian R-P iptable entries

Created by Ian R-P last modified
iptables.sh
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Use following command on a file with the iptable commands

    iptables-restore < iptables_file.txt

Random Commands

    # Required.
    *filter
    :INPUT ACCEPT [0:0]
    :FORWARD ACCEPT [0:0]
    :OUTPUT ACCEPT [0:0]

    # Required. Allow all loopback traffic
    -A INPUT -i lo -j ACCEPT

    # Required. Ensure any connections already made are accepted
    -A INPUT -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT

    # Required. Drop any invalid traffic.
    -A INPUT -m conntrack --ctstate INVALID -j DROP

    # Required. Allow Outgoing http connections (apt-get, curl, wget..etc)
    -A OUTPUT -o eth0 -p tcp --dport 80 -j ACCEPT
    -A OUTPUT -o eth0 -p tcp --dport 443 -j ACCEPT
    -A OUTPUT -o eth0 -p tcp --dport 25 -j ACCEPT
    -A OUTPUT -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT

    # Allow droplet to connect to mysql server in private network
    -A INPUT -i eth1 -p tcp --dport 3306 -m conntrack --ctstate NEW,ESTABLISHED -j ACCEPT
    -A OUTPUT -o eth1 -p tcp --sport 3306 -m conntrack --ctstate ESTABLISHED -j ACCEPT

    # Allow world access to HTTP and HTTPS
    -A INPUT -i eth0 -p tcp -m multiport --dports 80,443 -m conntrack --ctstate NEW,ESTABLISHED -j ACCEPT
    -A OUTPUT -o eth0 -p tcp -m multiport --sports 80,443 -m conntrack --ctstate ESTABLISHED -j ACCEPT

    # Allow outside world ssh into droplet
    -A INPUT -i eth0 -p tcp -m tcp --dport 22 -m conntrack --ctstate NEW,ESTABLISHED -j ACCEPT
    -A OUTPUT -o eth0 -p tcp -m tcp --sport 22 -m conntrack --ctstate NEW,ESTABLISHED -j ACCEPT

    # Allow SSH from inside droplet to outside world
    -A INPUT -i eth0 -p tcp -m tcp --sport 22 -m conntrack --ctstate NEW,ESTABLISHED -j ACCEPT
    -A OUTPUT -o eth0 -p tcp -m tcp --dport 22 -m conntrack --ctstate NEW,ESTABLISHED -j ACCEPT

    # Allow external IP address access via ssh into droplet
    -A INPUT -i eth0 -p tcp -m tcp --dport 22 -s 217.25.35.62 -m conntrack --ctstate NEW,ESTABLISHED -j ACCEPT
    -A OUTPUT -o eth0 -p tcp -m tcp --sport 22 -d 217.25.35.62 -m conntrack --ctstate NEW,ESTABLISHED -j ACCEPT

    # Allow range of ports on private network only
    -A INPUT -i eth1 -p tcp -m tcp --sport 9200:9400 -j ACCEPT

    # Allow internal connection to amazon s3 service for backups
    -A INPUT -i eth0 -p tcp -m tcp --sport 443 -m conntrack --ctstate ESTABLISHED -j ACCEPT
    -A OUTPUT -o eth0 -p tcp -m tcp --dport 443 -m conntrack --ctstate NEW,ESTABLISHED -j ACCEPT

    # Allow git
    -A INPUT -i eth0 -p tcp --sport 9418 -m conntrack --ctstate ESTABLISHED -j ACCEPT
    -A OUTPUT -o eth0 -p tcp --dport 9418 -m conntrack --ctstate NEW,ESTABLISHED -j ACCEPT

    # Allow a random port 62349
    -A INPUT -i eth0 -p tcp --dport 62349 -m conntrack --ctstate NEW,ESTABLISHED -j ACCEPT
    -A OUTPUT -o eth0 -p tcp --sport 62349 -m conntrack --ctstate ESTABLISHED -j ACCEPT

    # Allow DNS lookups
    -A INPUT -i eth0 -p udp --sport 53 -m conntrack --ctstate ESTABLISHED -j ACCEPT
    -A INPUT -i eth0 -p tcp --sport 53 -m conntrack --ctstate ESTABLISHED -j ACCEPT
    -A OUTPUT -o eth0 -p udp --dport 53 -m conntrack --ctstate NEW,ESTABLISHED -j ACCEPT
    -A OUTPUT -o eth0 -p tcp --dport 53 -m conntrack --ctstate NEW,ESTABLISHED -j ACCEPT

    # Allow outgoing mail ports
    -A OUTPUT -p tcp -m multiport --dports 110,143,465,587,995 -j ACCEPT

    # Allow forwarding data from internal to external
    -A FORWARD -i eth1 -o eth0 -j ACCEPT

    # Allow outgoing pings
    -A OUTPUT -o eth0 -p icmp --icmp-type echo-request -j ACCEPT

    # Block all other traffic on eth0 (public network)
    -A INPUT -i eth0 -j REJECT
    -A OUTPUT -o eth0 -j DROP

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