Block known dirty hosts from reaching your machine

wget -qO -|awk '!/#|[a-z]/&&/./{print "iptables -A INPUT -s "$1" -j DROP"}'
Blacklisted is a compiled list of all known dirty hosts (botnets, spammers, bruteforcers, etc.) which is updated on an hourly basis. This command will get the list and create the rules for you, if you want them automatically blocked, append |sh to the end of the command line. It's a more practical solution to block all and allow in specifics however, there are many who don't or can't do this which is where this script will come in handy. For those using ipfw, a quick fix would be {print "add deny ip from "$1" to any}. Posted in the sample output are the top two entries. Be advised the blacklisted file itself filters out RFC1918 addresses (10.x.x.x, 172.16-31.x.x, 192.168.x.x) however, it is advisable you check/parse the list before you implement the rules
Sample Output
wget -qO -|awk '!/#|[a-z]/&&/./{print "iptables -A INPUT -s "$1" -j DROP"}'|head -n 2
iptables -A INPUT -s -j DROP
iptables -A INPUT -s -j DROP

To have them automatically blocked:
wget -qO -|awk '!/#|[a-z]/&&/./{print "iptables -A INPUT -s "$1" -j DROP"}'|sh

By: sil
2009-02-18 16:08:23

What Others Think

Great size list.
BADmd · 596 weeks and 4 days ago
Can someone help me understand the "!/#|[a-z]/&&/./" portion of the awk string? Would incorporating 'sort' into the command, before feeding to iptables, improve lookup efficiency (the blacklist is not numerically ordered) or is awk accomplishing this? Thank you.
surfkid · 528 weeks and 1 day ago
! means not so !/#|[a-z]/ is: ignore anything with a comment and [a-z] is ignore letters. && is an /./ so: awk '!/# ignore anything with pound sign |[a-z] ignore any letters && and /./ show me anything with a period awk '!/ignore_this_string|ignore_that_string/&&/show_this_one/{print $FIELD}' its the equivalent of grep -v "#|[a-z]"
sil · 528 weeks and 1 day ago
Sil, great explanation (and fast response) thank you! Thoughts on sorting the list?
surfkid · 528 weeks and 1 day ago
To explain things better, I figured I'd show an example: So I created a file called test with 10 lines, the first three are duplicates: more test Let's number them: sed '/./=' test | sed '/./N; s/\n/ /' 1 2 3 4 5 6 7 8 9 10 So we see lines 1, 2, 3 are the same... There are a few ways to sort them uniquely. Since I began using awk, here is how to do so with awk: awk '!/#|[a-z]/&&/./{print "iptables -A INPUT -s "$1" -j DROP" | "sort -u"}' test Notice how I use the sort command inside awk? There is no reason to re-pipe it through to sort: awk by itself awk '!/#|[a-z]/&&/./{print "iptables -A INPUT -s "$1" -j DROP"}' test iptables -A INPUT -s -j DROP iptables -A INPUT -s -j DROP iptables -A INPUT -s -j DROP iptables -A INPUT -s -j DROP iptables -A INPUT -s -j DROP iptables -A INPUT -s -j DROP iptables -A INPUT -s -j DROP iptables -A INPUT -s -j DROP iptables -A INPUT -s -j DROP iptables -A INPUT -s -j DROP awk with sort -u (-u is for unique instead of: more filename | sort | uniq) awk '!/#|[a-z]/&&/./{print "iptables -A INPUT -s "$1" -j DROP"}' test | sort -u iptables -A INPUT -s -j DROP iptables -A INPUT -s -j DROP iptables -A INPUT -s -j DROP iptables -A INPUT -s -j DROP iptables -A INPUT -s -j DROP iptables -A INPUT -s -j DROP iptables -A INPUT -s -j DROP iptables -A INPUT -s -j DROP Why bother going through this when I can just use sort inside of awk. The uglier and bloated way would be something like: awk '!/#|[a-z]/&&/./{print "iptables -A INPUT -s "$1" -j DROP"}' filename | sort | uniq Or even uglier: curl | ruby -ne 'puts $_ unless $_ == @prev; @prev = $_' | awk '{print "iptables -A INPUT -s "$1" -j DROP"}'
sil · 528 weeks and 1 day ago
This is exactly what I needed to see! Sil, you rock. The meticulous instruction was so helpful, particularly the placement of sort and its unique switch within awk versus (unnecessary) discreet use. I will use: awk '!/#|[a-z]/&&/./{print "iptables -A INPUT -s "$1" -j DROP" | "sort -u"}'
surfkid · 528 weeks and 1 day ago
Excellent Contribution. Thank you.
LAN4N6 · 502 weeks and 6 days ago

What do you think?

Any thoughts on this command? Does it work on your machine? Can you do the same thing with only 14 characters?

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