Getting DDosed Attacked any advice?

Discussion in 'Site & Server Administration' started by Davey Crocket, May 28, 2008.

  1. #1
    Anyone have any advice for this type of attack?
    My webhost tried ip banning but it isn't stopping the bot from overloading my server.
     
    Davey Crocket, May 28, 2008 IP
  2. LittleJonSupportSite

    LittleJonSupportSite Peon

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    #2
    Create firewall rule and deny all form the subnet attacking.

    Can you see in the logs how it is attacking and from where?

    Many ways to stop the attack but without logs I really can't see what's going on.
     
    LittleJonSupportSite, May 28, 2008 IP
  3. Orien

    Orien Active Member

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    #3
    What type of attack and where is it targeted to?
     
    Orien, May 28, 2008 IP
  4. Davey Crocket

    Davey Crocket Well-Known Member

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    #4
    They are hitting port 80 at about 4 megs a second.
     
    Davey Crocket, May 28, 2008 IP
  5. Orien

    Orien Active Member

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    #5
    Are there a bunch of connections from a small # of IPs or few connections but from millions of IPs?
     
    Orien, May 28, 2008 IP
  6. xous

    xous Active Member

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    #6
    The best way to attempt to mitigate this issue is to have your host null route the attacking network(s) at their edge router.

    You should also be contacting the attacking network(s) abuse handle and provide them with the details of the issue. They may or may not take any action but if they don't you can always contact their upstream provider.
     
    xous, May 29, 2008 IP
  7. olddocks

    olddocks Notable Member

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    #7
    install mod_evasive on your apache to protect from ddos attacks.
    see this

    it would help if you install a firewall (CSF/APF) against brute force attacks. dont leave it open!
     
    olddocks, May 29, 2008 IP
  8. TTS

    TTS Peon

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    #8
    Same problem here. Can anyone suggest a shared host that can actually do something about this?
     
    TTS, May 29, 2008 IP
  9. shuttle

    shuttle Active Member

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    #9
    The only good protection against massive and sophisticated attacks is to hire a company that specializes in DDoS mitigation. Mind you that you do not want to contact such company when the attack is taking place, because the emergency fees are quite dear!

    Make sure you deploy such a service before the attack even reaches your network edge!!!
     
    shuttle, May 30, 2008 IP
  10. jayshah

    jayshah Peon

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    #10
    jayshah, May 30, 2008 IP
  11. DnHype

    DnHype Active Member

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    #11
    Have Iptables on your box ?
    Dos Attack generaly come from many "zombie" computer.
    They generaly use ICMP¨, UDP protocole tu attack you.
    My Advice, Drop ICMP Packet from any kind, this will then turn off the ping reply from your server + tracert and some other things.
    Close all port that you dont run service on from 10000 to 65365 cause there'r generaly unused and allway open on major box.
    and all other under that are unused.
    Instead of block the ip that attack come from, block the traffic protocole they use to down you.
     
    DnHype, May 30, 2008 IP
  12. olddocks

    olddocks Notable Member

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    #12
    i think if it is TCP that would be a problem
     
    olddocks, May 30, 2008 IP
  13. jayshah

    jayshah Peon

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    #13
    Block a protocol? Loose UDP or TCP and you'll be in trouble.
     
    jayshah, May 31, 2008 IP
  14. xous

    xous Active Member

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    #14
    Hi,

    I should point out that while making software changes (i.e. iptables, mod_evasive, etc.) can reduce the amount of server load that the DDoS attack can cause but is absolutely pointless if the DDoS attack is large enough to saturate your up-link.

    For example if your (or your host or their upstream provider) link is 10Mbit/s and an you are getting a 12Mbit/s DDoS then it really doesn't matter what you do on the server as little, if any, legitimate traffic will get through anyway.
     
    xous, May 31, 2008 IP
  15. jayshah

    jayshah Peon

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    #15
    Of course. If it gets out of hand, contact your IDC and have them null route the offending IP(s) at their Edge routers. Note, if it's too bad to null route their ips, some null route YOURS until the attack stops. You have been warned (hence I have never contacted the IDC). If you are forced, null route your own IP (drop the binding to the interface) and shift everyone to a new IP.
     
    jayshah, Jun 1, 2008 IP
  16. calum

    calum Peon

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    #16
    If it gets terrible then ask you dc to null route the server until it stops. If it is so bad that the server doesn't respond anyway then you have nothing to lose.
     
    calum, Jun 1, 2008 IP