[TriLUG] Iptables rule sets

Wed May 21 15:13:09 EDT 2014

You left out a critical detail.  What are you trying to accomplish by using
iptables?

On Wed, May 21, 2014 at 3:10 PM, Gary Baker <garybaker9 at gmail.com> wrote:

> Hello All:
>
> I am trying to switch to iptables in Vector 7.0 (which is a frontend for
> Slacware 14.0).
>
> I will post the rule set I am planning to use:
>
> # Modify this file accordingly for your specific requirement.
> # http://www.thegeekstuff.com
> # 1. Delete all existing rules
> iptables -F
>
> # 2. Set default chain policies
> iptables -P INPUT DROP
> iptables -P FORWARD DROP
> iptables -P OUTPUT DROP
>
> # 3. Block a specific ip-address
> #BLOCK_THIS_IP="x.x.x.x"
> #iptables -A INPUT -s "$BLOCK_THIS_IP" -j DROP
>
> # 4. Allow ALL incoming SSH
> #iptables -A INPUT -i eth0 -p tcp --dport 22 -m state --state
> NEW,ESTABLISHED -j ACCEPT
> #iptables -A OUTPUT -o eth0 -p tcp --sport 22 -m state --state ESTABLISHED
> -j ACCEPT
>
> # 5. Allow incoming SSH only from a sepcific network
> #iptables -A INPUT -i eth0 -p tcp -s 192.168.200.0/24 --dport 22 -m state
> --state NEW,ESTABLISHED -j ACCEPT
> #iptables -A OUTPUT -o eth0 -p tcp --sport 22 -m state --state ESTABLISHED
> -j ACCEPT
>
> # 6. Allow incoming HTTP
> #iptables -A INPUT -i eth0 -p tcp --dport 80 -m state --state
> NEW,ESTABLISHED -j ACCEPT
> #iptables -A OUTPUT -o eth0 -p tcp --sport 80 -m state --state ESTABLISHED
> -j ACCEPT
>
> # Allow incoming HTTPS
> #iptables -A INPUT -i eth0 -p tcp --dport 443 -m state --state
> NEW,ESTABLISHED -j ACCEPT
> #iptables -A OUTPUT -o eth0 -p tcp --sport 443 -m state --state ESTABLISHED
> -j ACCEPT
>
> # 7. MultiPorts (Allow incoming SSH, HTTP, and HTTPS)
> iptables -A INPUT -i eth0 -p tcp -m multiport --dports 22,80,443 -m state
> --state NEW,ESTABLISHED -j ACCEPT
> iptables -A OUTPUT -o eth0 -p tcp -m multiport --sports 22,80,443 -m state
> --state ESTABLISHED -j ACCEPT
>
> # 8. Allow outgoing SSH
> iptables -A OUTPUT -o eth0 -p tcp --dport 22 -m state --state
> NEW,ESTABLISHED -j ACCEPT
> iptables -A INPUT -i eth0 -p tcp --sport 22 -m state --state ESTABLISHED -j
> ACCEPT
>
> # 9. Allow outgoing SSH only to a specific network
> #iptables -A OUTPUT -o eth0 -p tcp -d 192.168.101.0/24 --dport 22 -m state
> --state NEW,ESTABLISHED -j ACCEPT
> #iptables -A INPUT -i eth0 -p tcp --sport 22 -m state --state ESTABLISHED
> -j ACCEPT
>
> # 10. Allow outgoing HTTPS
> iptables -A OUTPUT -o eth0 -p tcp --dport 443 -m state --state
> NEW,ESTABLISHED -j ACCEPT
> iptables -A INPUT -i eth0 -p tcp --sport 443 -m state --state ESTABLISHED
> -j ACCEPT
>
> # 11. Load balance incoming HTTPS traffic
> #iptables -A PREROUTING -i eth0 -p tcp --dport 443 -m state --state NEW -m
> nth --counter 0 --every 3 --packet 0 -j DNAT --to-destination
> 192.168.1.101:443
> #iptables -A PREROUTING -i eth0 -p tcp --dport 443 -m state --state NEW -m
> nth --counter 0 --every 3 --packet 1 -j DNAT --to-destination
> 192.168.1.102:443
> #iptables -A PREROUTING -i eth0 -p tcp --dport 443 -m state --state NEW -m
> nth --counter 0 --every 3 --packet 2 -j DNAT --to-destination
> 192.168.1.103:443
>
> # 12. Ping from inside to outside
> iptables -A OUTPUT -p icmp --icmp-type echo-request -j ACCEPT
> iptables -A INPUT -p icmp --icmp-type echo-reply -j ACCEPT
>
> # 13. Ping from outside to inside
> iptables -A INPUT -p icmp --icmp-type echo-request -j ACCEPT
> iptables -A OUTPUT -p icmp --icmp-type echo-reply -j ACCEPT
>
> # 14. Allow loopback access
> iptables -A INPUT -i lo -j ACCEPT
> iptables -A OUTPUT -o lo -j ACCEPT
>
> # 15. Allow packets from internal network to reach external network.
> # if eth1 is connected to external network (internet)
> # if eth0 is connected to internal network (192.168.1.x)
> iptables -A FORWARD -i eth0 -o eth1 -j ACCEPT
>
> # 16. Allow outbound DNS
> #iptables -A OUTPUT -p udp -o eth0 --dport 53 -j ACCEPT
> #iptables -A INPUT -p udp -i eth0 --sport 53 -j ACCEPT
>
> # 17. Allow NIS Connections
> # rpcinfo -p | grep ypbind ; This port is 853 and 850
> #iptables -A INPUT -p tcp --dport 111 -j ACCEPT
> #iptables -A INPUT -p udp --dport 111 -j ACCEPT
> #iptables -A INPUT -p tcp --dport 853 -j ACCEPT
> #iptables -A INPUT -p udp --dport 853 -j ACCEPT
> #iptables -A INPUT -p tcp --dport 850 -j ACCEPT
> #iptables -A INPUT -p udp --dport 850 -j ACCEPT
>
> # 18. Allow rsync from a specific network
> iptables -A INPUT -i eth0 -p tcp -s 192.168.101.0/24 --dport 873 -m state
> --state NEW,ESTABLISHED -j ACCEPT
> iptables -A OUTPUT -o eth0 -p tcp --sport 873 -m state --state ESTABLISHED
> -j ACCEPT
>
> # 19. Allow MySQL connection only from a specific network
> iptables -A INPUT -i eth0 -p tcp -s 192.168.200.0/24 --dport 3306 -m state
> --state NEW,ESTABLISHED -j ACCEPT
> iptables -A OUTPUT -o eth0 -p tcp --sport 3306 -m state --state ESTABLISHED
> -j ACCEPT
>
> # 20. Allow Sendmail or Postfix
> iptables -A INPUT -i eth0 -p tcp --dport 25 -m state --state
> NEW,ESTABLISHED -j ACCEPT
> iptables -A OUTPUT -o eth0 -p tcp --sport 25 -m state --state ESTABLISHED
> -j ACCEPT
>
> # 21. Allow IMAP and IMAPS
> iptables -A INPUT -i eth0 -p tcp --dport 143 -m state --state
> NEW,ESTABLISHED -j ACCEPT
> iptables -A OUTPUT -o eth0 -p tcp --sport 143 -m state --state ESTABLISHED
> -j ACCEPT
>
> iptables -A INPUT -i eth0 -p tcp --dport 993 -m state --state
> NEW,ESTABLISHED -j ACCEPT
> iptables -A OUTPUT -o eth0 -p tcp --sport 993 -m state --state ESTABLISHED
> -j ACCEPT
>
> # 22. Allow POP3 and POP3S
> iptables -A INPUT -i eth0 -p tcp --dport 110 -m state --state
> NEW,ESTABLISHED -j ACCEPT
> iptables -A OUTPUT -o eth0 -p tcp --sport 110 -m state --state ESTABLISHED
> -j ACCEPT
>
> iptables -A INPUT -i eth0 -p tcp --dport 995 -m state --state
> NEW,ESTABLISHED -j ACCEPT
> iptables -A OUTPUT -o eth0 -p tcp --sport 995 -m state --state ESTABLISHED
> -j ACCEPT
>
> # 23. Prevent DoS attack
> iptables -A INPUT -p tcp --dport 80 -m limit --limit 25/minute
> --limit-burst 100 -j ACCEPT
>
> # 24. Port forwarding 422 to 22
> iptables -t nat -A PREROUTING -p tcp -d 192.168.102.37 --dport 422 -j DNAT
> --to 192.168.102.37:22
> iptables -A INPUT -i eth0 -p tcp --dport 422 -m state --state
> NEW,ESTABLISHED -j ACCEPT
> iptables -A OUTPUT -o eth0 -p tcp --sport 422 -m state --state ESTABLISHED
> -j ACCEPT
>
> # 25. Log dropped packets
> iptables -N LOGGING
> iptables -A INPUT -j LOGGING
> iptables -A LOGGING -m limit --limit 2/min -j LOG --log-prefix "IPTables
> Packet Dropped: " --log-level 7
> iptables -A LOGGING -j DROP
>
> I am sure that this rule set needs editing and additional rules added to
> it.
>
> Please give me pointers, rules or tell me what you think. Do you still use
> iptables?
>
> Anyone who wants to can keep my email and email me if they want to. I will
> try to keep it updated.
>
>
> New list member,
>
>
> Gary Baker
> --
> This message was sent to: Aaron S. Joyner <aaron at joyner.ws>
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