If you want to monitor a specific tcp port on Icinga2 you just need to add another tcp variable:

object Host "host-web" {
     import "generic-host-tpl"

     address = "YOUR_SERVER_IP_ADDRESS"
     vars.os = "Linux"

     vars.tcp["OPTIONAL_NAME"]={
         tcp_port=8181
     }

Here in above sample we are monitoring port 8181 of host-web which has the IP address of YOUR_SERVER_IP_ADDRESS (change it to your server ip address remote or local).

#linux #monitoring #sysadmin #icinga2 #host #tcp #port

View open ports without netstat or other tool:

# Get all open ports in hex format
declare -a open_ports=($(cat /proc/net/tcp | grep -v "local_address" | awk '{ print $2 }' | cut -d':' -f2))
# Show all open ports and decode hex to dec
for port in ${open_ports[*]}; do echo $((0x${port})); done

#linux #ports #netstat #tcp #open_ports #sysadmin

How to create a network scanner in python using socket?

socket library is used to work with network and here we use it to simulate a network scanner.

A network scanner iterates over all the possible IP addresses on the network and for every IP it tries to connect to one of the ports. If the connection was successful (ACK received) we know that this host is available at the given IP address. This is the philosophy of a network scanner.

For now we just try to connect to a specific port of the server and leave the other parts to you to iterate and check the status:

import socket

  addr = '172.16.132.20'
  port = 27017

  socket_obj = socket.socket(socket.AF_INET,socket.SOCK_STREAM)
  socket.setdefaulttimeout(1)
  result = socket_obj.connect_ex((addr,port))
  print result
  socket_obj.close()

The above code connects to the given address:port and returns a status code. If returned code is 0 then the
port is open otherwise the port is probably blocked/closed.

#python #socket #network #tcp #tcp_scanner