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Re:Share some iptables configuration options
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eXcalibre
Posts: 1
Not sure if i am allowed to post here, but
I am looking for an IPtables config that will try to stop brute force imap logins.
is there a way i can put a time limit on the amount of attempts that an ip has to log into IMAP port and block the address if its exceeded?
Many thanks in advance.
0
Comments
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This is my old firewall script with the comments included, this simple one worked pretty well.
Since then I have made a much more complicated and modular one, I will share that when it is complete.#!/bin/bash ######################################################## # START THE FIREWALL SCRIPT # ######################################################## # Flush the current rules iptables -F # Block all forwarding iptables -A FORWARD -s 0/0 -j DROP # Allow all input into loopback iptables -A INPUT -i lo -j ACCEPT # Allow 4 pings per minute to block ping DOS attacks iptables -A INPUT -p icmp --icmp-type echo-request -m limit --limit 4/m -j ACCEPT # Allow all echo replies including destination unreachable and time exceeded iptables -A INPUT -p icmp --icmp-type echo-reply -j ACCEPT iptables -A INPUT -p icmp --icmp-type destination-unreachable -j ACCEPT iptables -A INPUT -p icmp --icmp-type time-exceeded -j ACCEPT # Block all other icmp traffic iptables -A INPUT -p icmp -j DROP # Allow all response traffic iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT # block all other incoming traffic iptables -A INPUT -j DROP # Display confirmation message RED=$'\e[31;01m' NORMAL=$'\e[0m' echo "${RED}Firewall Started.....${NORMAL}"
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That is a nice addition, that can be usful to work with the invalid attempt option in sshd to prevent breakins.0
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I am not fully versed in the communication methods and ports used for IMAP communication, but if you can pin down the basic packet structure of IMAP logins then you can develop n iptable rule to accomplish your task.0
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I think the best way to prevent brute force attack's to your logins on any service is not in the firewall, try using pam modules, for ssh try pam-abl (http://tech.tolero.org/blog/en/linux/ssh-password-brute-force-protection).0
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Tha pam option is definitely a good recommendation, in general I prefer to avoid pam because of the frequency in which vulnerabilities are discovered.0
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I don't know now that you'd like firewall setings for servers or desktops but I think that for desktops it's enough this simple rules:
iptables -F # Security policy iptables -P INPUT DROP iptables -P FORWARD DROP iptables -P OUTPUT DROP # Accept loopback iptables -A INPUT -i lo -j ACCEPT iptables -A FORWARD -o lo -j ACCEPT # Incoming and forward rules iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT iptables -A FORWARD -m state --state ESTABLISHED,RELATED -j ACCEPT # Outgoing rules iptables -A OUTPUT -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT
If someone want, can also log traffics and attacks attempt0 -
Thank you for the script roobal, your submission is simple and clean which makes it perfect for new users.0
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