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Commands using netstat from sorted by
Terminal - Commands using netstat - 118 results
netstat -an | grep ESTABLISHED | awk '{print $5}' | awk -F: '{print $1}' | sort | uniq -c | awk '{ printf("%s\t%s\t",$2,$1) ; for (i = 0; i < $1; i++) {printf("*")}; print "" }'
2009-04-27 22:02:19
User: knassery
Functions: awk grep netstat sort uniq

Written for linux, the real example is how to produce ascii text graphs based on a numeric value (anything where uniq -c is useful is a good candidate).

netstat -ntu | awk '{print $5}' | cut -d: -f1 | sort | uniq -c | sort -n
2009-03-28 21:02:26
User: tiagofischer
Functions: awk cut netstat sort uniq

Here is a command line to run on your server if you think your server is under attack. It prints our a list of open connections to your server and sorts them by amount.

BSD Version:

netstat -na |awk '{print $5}' |cut -d "." -f1,2,3,4 |sort |uniq -c |sort -nr
netstat -atn | awk ' /tcp/ {printf("%s\n",substr($4,index($4,":")+1,length($4) )) }' | sed -e "s/://g" | sort -rnu | awk '{array [$1] = $1} END {i=32768; again=1; while (again == 1) {if (array[i] == i) {i=i+1} else {print i; again=0}}}'
2009-03-27 20:38:43
User: mpb
Functions: awk netstat sed sort

Some commands (such as netcat) have a port option but how can you know which ports are unused?

netstat -an | grep -i listen
netstat -antuwp | egrep "(^[^t])|(^tcp.*LISTEN)"
netstat -tap | grep mysql
netstat -alnp | grep ::80
netstat -an | grep -i listen
2009-02-19 19:27:49
User: scubacuda
Functions: grep netstat

From 'man netstat'

"netstat -i | -I interface [-abdnt] [-f address_family] [-M core] [-N system]

Show the state of all network interfaces or a single interface

which have been auto-configured (interfaces statically configured

into a system, but not located at boot time are not shown). An

asterisk (``*'') after an interface name indicates that the

interface is ``down''. If -a is also present, multicast

addresses currently in use are shown for each Ethernet interface

and for each IP interface address. Multicast addresses are shown

on separate lines following the interface address with which they

are associated. If -b is also present, show the number of bytes

in and out. If -d is also present, show the number of dropped

packets. If -t is also present, show the contents of watchdog


lsof -p $(netstat -ltpn|awk '$4 ~ /:80$/ {print substr($7,1,index($7,"/")-1)}')| awk '$9 ~ /access.log$/ {print $9| "sort -u"}'
2009-02-19 16:11:54
User: rjamestaylor
Functions: awk netstat

Ever logged into a *nix box and needed to know which webserver is running and where all the current access_log files are? Run this one liner to find out. Works for Apache or Lighttpd as long as CustomLog name is somewhat standard. HINT: works great as input into for loop, like this:

for i in `lsof -p $(netstat -ltpn|awk '$4 ~ /:80$/ {print substr($7,1,index($7,"/")-1)}')| awk '$9 ~ /access.log$/ {print $9| "sort -u"}'` ; do echo $i; done

Very useful for triage on unfamiliar servers!

netstat -alpn | grep :80 | awk '{print $4}' |awk -F: '{print $(NF-1)}' |sort | uniq -c | sort -n
netstat -putona
2009-02-16 19:14:35
User: starchox
Functions: netstat

-p PID and name of the program

-u on a UDP port.

-t also TCP ports

-o networking timer

-n numeric IP addresses (don't resolve them)

-a all sockets

netstat -ntu | awk '{print $5}' | cut -d: -f1 | sort | uniq -c | sort -n | tail
2009-02-16 15:48:27
User: TuxOtaku
Functions: awk cut netstat sort uniq

This command does a tally of concurrent active connections from single IPs and prints out those IPs that have the most active concurrent connections. VERY useful in determining the source of a DoS or DDoS attack.

netstat -anl | grep :80 | awk '{print $5}' | cut -d ":" -f 1 | uniq -c | sort -n | grep -c IPHERE
2009-02-16 08:54:08
User: nullrouter
Functions: awk cut grep netstat sort uniq

This will tell you who has the most Apache connections by IP (replace IPHERE with the actual IP you wish to check). Or if you wish, remove | grep -c IPHERE for the full list.

netstat -pant 2> /dev/null | grep SYN_ | awk '{print $5;}' | cut -d: -f1 | sort | uniq -c | sort -n | tail -20
2009-02-16 08:49:38

List top 20 IP from which TCP connection is in SYN_RECV state.

Useful on web servers to detect a syn flood attack.

Replace SYN_ with ESTA to find established connections

netstat -anp |grep 'tcp\|udp' | awk '{print $5}' | sed s/::ffff:// | cut -d: -f1 | sort | uniq -c | sort -n
netstat -plunt
2009-02-06 06:04:32
Functions: netstat

-p Tell me the name of the program and it's PID

-l that is listening

-u on a UDP port.

-n Give me numeric IP addresses (don't resolve them)

-t oh, also TCP ports

sudo netstat -punta
netstat -ant | awk '{print $NF}' | grep -v '[a-z]' | sort | uniq -c