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Full Discussion: Help, SSH /ipfw block script
Top Forums Shell Programming and Scripting Help, SSH /ipfw block script Post 302612345 by dpreviti on Sunday 25th of March 2012 05:53:01 PM
Old 03-25-2012
Help, SSH /ipfw block script
Hello,

This is an SSH Block hammer script using ipfw, that I have modified for my own use. It is for a freenas 7.2 box which is FreeBSD based.

The script works, but if there is more then one hammer attack per day, my issue is the script reads the first five instances of refused or invalid users lines from the logs, not the most recent which is what I'd like it to do. Can some one better at scripting help me. The script is split into two searchs because of the need to parse the parentheses from the refused connections awk output.
TIA

DP

Script follows:
Code:
#!/bin/sh
#begin routine for refused connections
#del existing block rule
if ipfw show | awk '{print $1}' | grep -q 350 ; then
        ipfw delete 350
fi
#5 or more refused connections
awk '/refused/  {try[$(NF)]++}
END {for (h in try) if (try[h] > 5) print h}' /var/log/sshd.log |sed 's/[()]//g'|
while read ip
do
echo 'adding' $ip        
ipfw -q add 350 deny tcp from $ip to any in
done
#
#begin routine for invalid users
if ipfw show | awk '{print $1}' | grep -q 360 ; then
        ipfw delete 360
fi
awk '/Invalid user/ {try[$(NF)]++}
END {for (h in try) if (try[h] > 5) print h}' /var/log/sshd.log |
while read ip
do
echo 'adding' $ip        
ipfw -q add 360 deny tcp from $ip to any in
done

 

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LEARN ABOUT DEBIAN

ipaccounting

IPFW(4) 						   BSD Kernel Interfaces Manual 						   IPFW(4)

NAME

     ipfw -- IP packet filter and traffic accounting

SYNOPSIS

     To compile ipfw into the kernel, place the following option in the kernel configuration file:

	   options IPFIREWALL

     Other kernel options related to ipfw which may also be useful are:

	   options IPFIREWALL_DEFAULT_TO_ACCEPT
	   options IPFIREWALL_FORWARD
	   options IPFIREWALL_VERBOSE
	   options IPFIREWALL_VERBOSE_LIMIT=100

     To load ipfw as a module at boot time, add the following line into the loader.conf(5) file:

	   ipfw_load="YES"

DESCRIPTION

     The ipfw system facility allows filtering, redirecting, and other operations on IP packets travelling through network interfaces.

     The default behavior of ipfw is to block all incoming and outgoing traffic.  This behavior can be modified, to allow all traffic through the
     ipfw firewall by default, by enabling the IPFIREWALL_DEFAULT_TO_ACCEPT kernel option.  This option may be useful when configuring ipfw for
     the first time.  If the default ipfw behavior is to allow everything, it is easier to cope with firewall-tuning mistakes which may acciden-
     tally block all traffic.

     To enable logging of packets passing through ipfw, enable the IPFIREWALL_VERBOSE kernel option.  The IPFIREWALL_VERBOSE_LIMIT option will
     prevent syslogd(8) from flooding system logs or causing local Denial of Service.  This option may be set to the number of packets which will
     be logged on a per-entry basis before the entry is rate-limited.

     Policy routing and transparent forwarding features of ipfw can be enabled by IPFIREWALL_FORWARD kernel option.

     The user interface for ipfw is implemented by the ipfw(8) utility, so please refer to the ipfw(8) manpage for a complete description of the
     ipfw capabilities and how to use it.

SEE ALSO

     setsockopt(2), divert(4), ip(4), ipfw(8), sysctl(8), syslogd(8), pfil(9)

BSD
								 September 1, 2006							       BSD
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