| 1 |
On 07/09/2016 18:39, Grant wrote: |
| 2 |
>>>>>> Hi, my site is being ravaged by an IP but dropping the IP via |
| 3 |
>>>>>> shorewall is seeming to have no effect. I'm using his IP from nginx |
| 4 |
>>>>>> logs. IP blocking in shorewall has always worked before. What could |
| 5 |
>>>>>> be happening? |
| 6 |
>>>>> |
| 7 |
>>>>> |
| 8 |
>>>>> I'm blocking like this with the firewall running on the web server: |
| 9 |
>>>>> |
| 10 |
>>>>> /etc/shorewall/rules |
| 11 |
>>>>> DROP net:1.2.3.4 $FW |
| 12 |
>>>>> |
| 13 |
>>>>> Could shorewall/iptables see a different IP address than the one seen by nginx? |
| 14 |
>>>> |
| 15 |
>>>> |
| 16 |
>>>> Most likely the file is configured but the firewall service wasn't |
| 17 |
>>>> restarted or the rules no loaded. |
| 18 |
>>> |
| 19 |
>>> |
| 20 |
>>> I restarted shorewall plenty. :) I believe the issue was either a |
| 21 |
>>> persistent connection which conntrack-tools would have allowed me to |
| 22 |
>>> flush, or my blocking in /etc/shorewall/rules instead of |
| 23 |
>>> /etc/shorewall/blrules, or both. |
| 24 |
>>> |
| 25 |
>> |
| 26 |
>> What exactly is your issue? That is, what makes you think you even |
| 27 |
>> have an issue? |
| 28 |
>> |
| 29 |
>> The reason I ask is that all iptables is going to do is drop packets |
| 30 |
>> when they reach the kernel. They still go through your network and |
| 31 |
>> network card and consume some CPU (even more if you're logging them). |
| 32 |
>> If you're being flooded by a very large volume of packets then that |
| 33 |
>> will saturate your connection and simply dropping them at the server |
| 34 |
>> won't fix the latency this will cause for the good packets. In such |
| 35 |
>> an attack you need to block those packets as far upstream as you can |
| 36 |
>> before connections start getting saturated. This might be outside of |
| 37 |
>> your network perimeter. This is why DDoS attacks are so potent, if |
| 38 |
>> you use something like fail2ban to just set iptables are done you're |
| 39 |
>> fixing the barn doors after the horses have already left. |
| 40 |
> |
| 41 |
> |
| 42 |
> I said I was under attack but it was really just an unthrottled and |
| 43 |
> very greedy bot. fail2ban would have gotten him. But while we're on |
| 44 |
> the subject, how would you recommend thwarting a DDoS attack against a |
| 45 |
> dedicated server in a hosted environment? Cloudflare? |
| 46 |
|
| 47 |
A proper DDos? Phone your ISP and ask them to help you. You almost |
| 48 |
certainly don't have the resources. |
| 49 |
|
| 50 |
|
| 51 |
-- |
| 52 |
Alan McKinnon |
| 53 |
alan.mckinnon@×××××.com |
Archives