Find processes based on port number and kill them all.
ps -efl | grep PORT_NUMBER | kill -9 process_found_previously
how to complete the last column?
The problem with ps -efl | grep PORT_NUMBER is that PORT_NUMBER may match other columns in the output of ps as well (date, time, pid, ...). A potential killing spree if run by root!
I would do this instead :
PORT_NUMBER=1234
lsof -i tcp:${PORT_NUMBER} | awk 'NR!=1 {print $2}' | xargs kill 
Breakdown of command
lsof -i tcp:${PORT_NUMBER}) -- list all processes that is listening on that tcp portawk 'NR!=1 {print $2}') -- ignore first line, print second column of each linexargs kill) -- pass on the results as an argument to kill. There may be several. 
    
    1.) lsof -w -n -i tcp:8080
2.) kill -9 processId
 
    
    kill $( lsof -i:6000 -t )
Or if you need permissions:
sudo kill $( sudo lsof -i:6000 -t )
 
    
     
    
    Propose to use fuser command:
fuser -k -TERM -n tcp ${PORT_NUMBER}
 
    
    sudo fuser -k 8080/tcp
An easy one to remember.
This syntax is probably much more recent than the date of the question!
 
    
    ... | awk '{ print $4 }' | xargs kill -9
please test with "echo" instead of "kill" before running
To kill all processes listening on a particular port, e.g. port 8864
kill -9 $ \`lsof -i:8864 -t\`
Replace 8864 by the port you want.
 
    
    