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Thread: Block countries IP

  1. #1
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    Jul 2011
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    Block countries IP

    Hi all,

    I tried the method in this thread: http://ubuntuforums.org/showthread.php?t=1931490

    But I get this error message: "specified.4.4: invalid mask" for every entry from my cidr.txt.

    Here are a few address from my list:
    1.0.1.0/24
    1.0.2.0/23
    1.0.8.0/21
    1.0.32.0/19
    1.1.0.0/24
    1.1.2.0/23
    1.1.4.0/22
    1.1.8.0/21
    1.1.16.0/20
    1.1.32.0/19
    1.2.0.0/23
    1.2.2.0/24

    Any one knows why ?

    Thank you

  2. #2
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    Jul 2011
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    Re: Block countries IP

    the website who created my list was the problem apparently.

    I did another one using this site: https://www.countryipblocks.net/country_selection.php and I dont have the error message anymore.

    My only concern is the number of address in my list, 15000 ! Will this affect the performance of the system ?

    Thanks

  3. #3
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    Re: Block countries IP

    Quote Originally Posted by msavard View Post
    the website who created my list was the problem apparently.

    I did another one using this site: https://www.countryipblocks.net/country_selection.php and I dont have the error message anymore.

    My only concern is the number of address in my list, 15000 ! Will this affect the performance of the system ?

    Thanks
    It will, likely - iptables will have to look through all of those addresses each time a connection is incoming into the computer.
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  4. #4
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    Re: Block countries IP

    Ah, you solved your problem while I was writing my reply below. I'll leave it for posterity.

    15,000 rules would almost certainly impose some performance hit; the most rules I have on any machine I manage is about 900. They're on a dual-Xeon box though and have minimal effect. That said, iptables seems remarkably efficient for what it does with every packet entering or leaving the machine. Empirical research makes the most sense here. Impose the rules for a day or two and see if you can detect any difference.

    Quote Originally Posted by sandyd View Post
    It will, likely - iptables will have to look through all of those addresses each time a connection is incoming into the computer.
    That's a good point. I'm usually running publicly-visible servers, so I'm generally concerned about managing inbound traffic. On a firewall handling requests from LAN users, those 15,000 rules need not be consulted very often if you are careful about how you order your rules.

    Rules that block inbound traffic should generally come after rules that exempt obviously permitted traffic like that originating on the LAN or sent in reply to requests from LAN users like web pages. I usually make sure to place the rule
    Code:
    /sbin/iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
    right after the initial rule permitting the localhost interface. That insures that no time is wasted scanning the reply traffic with other rules. Right after that should be any rules that permit traffic from known hosts or addresses like the internal network. Only then should you add the rules that pertain to inbound traffic.


    Original response:

    I take it you're running the script called "ban" in the thread you referenced? Let's try a simpler approach first:

    Code:
    #!/bin/bash
    
    BAN_LIST=/path/to/list.txt
    
    for addr in $(cat BAN_LIST)
    do
        echo "Blocking $addr"
        /sbin/iptables -I INPUT -i eth0 -s $addr -j REJECT
    done
    All this does is read every line in list.txt and inserts (-I) a blocking rule in iptables at the top of the ruleset. This will place these rules ahead of any other rules you may already have that apply to the INPUT chain. It will also report each address before it inserts the rule. Create a file with these commands, mark it executable ("chmod a+x /path/to/program_file"), then run it. (Use "./program_file" if you are currently in the same directory as the program script.) What happens?
    Last edited by SeijiSensei; January 27th, 2014 at 08:19 PM.
    If you ask for help, please have the courtesy to check for responses and thank the people who helped you.

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  5. #5
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    Jul 2011
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    Re: Block countries IP

    thank you for your the information Seiji and Sandyd

  6. #6
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    Re: Block countries IP

    wrt: Performance... the .htaccess file is accessed for every 'hit' requested from the server.
    If those same 'blocks' were used in a .conf file, then they are only read once, but you'd have to restart apache[2]|http[d] after
    making an entry.

    If it's just countries you wish to block, try www.cloudflare.com
    Their control panel has country blocking. You can sign up for free and still use that feature.

    I have no association with cloudflare other than being a user of their services.
    If you care about visitor stats, you may not wish to use them, as all your hits will be CF IPs.

    There are ways around that however, depending on your software. These are noted on their site.


  7. #7
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    Re: Block countries IP

    For what it's worth, for another post one time, I did a test and added 64,009 INPUT chain rules. Yes, the throughput degradation was significant, but as Seiji mentions above the effect can be minimized with careful ordering of the rules. For my test, I purposely did not minimize the effect, but rather maximized it.
    Any follow-up information on your issue would be appreciated. Please have the courtesy to report back.

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