Security Basics mailing list archives
Re: Basic rules for IPTABLES protection
From: Pierre BETOUIN <info16 () unsigned ath cx>
Date: 25 Nov 2002 23:00:47 +0100
You can check the IP with the interface : When u rcv a packet from the external interface, deny packets which come with local IP (192.168.XXX.XXX or 172.16.XXX.XXX or others as non routing IP : 10.0.0.10,etc.) U can also just allow locals IP (if people don't have to send mail out from your LAN) And then, if you use a SMTP relay, just add its @ and deny others from external interface. Another good thing is to control the TCP/IP sequence and to check the tcp hand shake (--tcp-flags SYN,ACK,RST SYN) maybe, u'll want to add: iptables -A INPUT -m state --state NEW,RELATED -p tcp --syn -j ACCEPT iptables -A INPUT -m state --state ESTABLISHED -p tcp ! --syn -j ACCEPT I hope it was what u need. Pierre BETOUIN Le sam 23/11/2002 à 07:27, Erick Arturo Perez Huemer a écrit :
I am about to install a RedHat 8.0 box with iptables to act as our firewall for our internal network that consists of 20 machines. Besides doing a -j drop on our external interface when receives a
packet
with source equal to our internal network, what other measures we have to take? We do host an SMTP server but nothing else. I have read about blocking 10.x.x.x addresses but also read that "some" routers/sites use those addresses. Any anti-DoS rules? More settings? Or maybe a link to a site that offers suggestion for proper firewall configurations.... Thanks in advance, Erick.
-- Pierre BETOUIN <info16 () unsigned ath cx>
Current thread:
- Re: Basic rules for IPTABLES protection Pierre BETOUIN (Nov 26)
- <Possible follow-ups>
- Re: Basic rules for IPTABLES protection Pierre BETOUIN (Nov 26)
- Re: Basic rules for IPTABLES protection Pierre BETOUIN (Nov 26)