Hi.
This is my firewall script. I want to block IP spoofing.
Could you please advice or reference to any valid and recommended source
how to implement it?
Kernel: Linux asterisk-2018 4.15.0-32-generic #35-Ubuntu SMP Fri Aug 10
17:58:07 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux.
Thanks.
# Generated by iptables-save v1.6.1 on Mon Aug 20 14:22:20 2018
*filter
:INPUT DROP [0:0]
:FORWARD DROP [0:0]
:OUTPUT ACCEPT [9:796]
:ICMPALL - [0:0]
-A INPUT -m conntrack --ctstate INVALID -j DROP
-A INPUT -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A INPUT -i lo -j ACCEPT
-A INPUT -p tcp -m tcp --tcp-flags FIN,SYN,RST,ACK SYN -m limit --limit
1/sec --limit-burst 3 -j DROP
-A INPUT -s xxx.xxx.xxx.xxx/32 -p tcp -m tcp --dport 5061 -j ACCEPT
-A INPUT -s 192.168.2.0/24 -p udp -m multiport --dports 5060:5061 -j ACCEPT
-A INPUT -p udp -m multiport --dports 10000:20000 -j ACCEPT
-A INPUT -s 192.168.2.0/24 -p tcp -m tcp --dport 22 -j ACCEPT
-A INPUT -p tcp -m iprange --src-range 192.168.1.1-192.168.2.255 -m tcp
--dport 80 -j ACCEPT
-A INPUT -p icmp -m icmp --icmp-type any -j ICMPALL
-A INPUT -m limit --limit 10/min -j LOG --log-prefix "[netfilter] "
-A ICMPALL -p icmp -f -j DROP
-A ICMPALL -p icmp -m icmp --icmp-type 0 -j ACCEPT
-A ICMPALL -p icmp -m icmp --icmp-type 3 -j ACCEPT
-A ICMPALL -p icmp -m icmp --icmp-type 4 -j ACCEPT
-A ICMPALL -p icmp -m icmp --icmp-type 8 -j ACCEPT
-A ICMPALL -p icmp -m icmp --icmp-type 11 -j ACCEPT
-A ICMPALL -p icmp -j DROP
