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attack ? Find out with netstat !
Are you under a DoS or DDoS attack ? Find out
with netstat !
28 Nov 2011/4 Comments/in Security/by Admin
Your server appearing pretty slow could be many things from
wrong configs, scripts and dodgy hardware but sometimes it could be
because someone is flooding your server with traffic known as DoS (
Denial ofService ) or DDoS ( Distributed Denial of Service ) it
could also be that your server itself is part of a
botnet and is being used to attack other networks, in this case
its always a good idea to run scans withsoftware such as ClamAV and
RootKit Hunter as a precaution or even higher a professional to
check it outfor you if your not confident enough to do it on your
own.
Furthermore whenever a client connects to a server via network,
a connection is established and openedon the system. On a busy high
load server, the number of connections connected to the server can
be runinto large amount till hundreds if not thousands. Find out
and get a list of connections on the server byeach node, client or
IP address is useful for system scaling planning, and in most
cases, detect anddetermine whether a web server is under DoS or
DDoS attack
Take a look at these handy netstat commands below that will
surely help you determine wether your underattack or are part of an
attack.
net st at - na
Display all active Internet connections to the server and only
established connections are included.
net st at - an | gr ep : 80 | sor t
Show only active Internet connections to the server on port 80
and sort the results. Useful in detecting asingle flood by allowing
you to recognize many connections coming from one IP.
netst at - n - p| gr ep SYN_REC | wc - l
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To find out how many active SYNC_REC are occurring on the
server. The number should be pretty low,preferably less than 5. On
DoS attack incidents or mail bombs, the number can jump to pretty
high.However, the value always depends on system, so a high value
may be average on another server.
net st at - n - p | gr ep SYN_REC | sor t - u
List all IP addresses involved.
net st at - n - p | gr ep SYN_REC | awk ' {pr i nt $5}' | awk -
F: ' {pr i nt $1}'
List all the unique IP addresses of the nodes that are sending
SYN_REC connection status.
net st at - nt u | awk ' {pri nt $5}' | cut - d: - f 1 | sort |
uni q - c | sort - n
Use netstat command to calculate and count the number of
connections each IP address makes to theserver.
net st at - anp | grep ' t cp\ | udp' | awk ' {pri nt $5}' | cut
- d: - f 1 | sort | uni q - c | sort
List the number of connections the IPs are making to the server
using TCP or UDP protocol.
net st at - nt u | gr ep ESTAB | awk ' {pr i nt $5}' | cut - d:
- f 1 | sor t | uni q - c | sor t - nr
Check on ESTABLISHED connections instead of all connections, and
display the number of connectionsfor each IP.
net st at - pl an| gr ep : 80| awk {' pr i nt $5' }| cut - d: -
f 1| sor t | uni q - c| sor t - nk 1
Show a list IP addresss and its number of connections that are
connecting to port 80 on the server. Port80 is used mainly by the
HTTP protocol.
Tags:DDoS, DoS,Netstat
4 replies
mkhudasays:May 7, 2013 at 3:17 PM
my website is run very slowly at sometimes. .i think its ddos or
maybe server maintenance. .
Reply
1.
thoklingsays:November 18, 2013 at 7:49 AM
If your Website is running slow and you have shell access, run
top. The first line contains theload average of the system: each
1.00 means a full CPU worth of processing power is being used.
If that appears untoward, then the regularly-updating list of
processes underneath the highlightedbar can help. %CPU is the
important field: 100% means its using a full CPU worth of
processingpower. If any process is hogging the CPU for an undesired
amount of time, research ways to reducethe CPU footprint of that
process. Either its not configured properly, it needs to be
replaced, or the
2.
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VM sharing system of the host is not that efficient.
Reply
Anonsays:
November 22, 2013 at 4:14 AM
Most of these do not work on my machine. Running Windows 7
Ultimate.
Reply
3.
Hasan Demirsays:January 8, 2014 at 1:40 PM
I needed it
Reply
4.
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