Install and Configure Nagios On CentOS 6.7

Nagios is an open source software that can be used for network and infrastructure monitoring. Nagios will monitor servers, switches, applications and services. It alerts the System Administrator when something went wrong and also alerts back when the issues has been rectified.

With Nagios you can:

– Monitor your entire IT infrastructure.
– Identify problems before they occur.
– Know immediately when problems arise.
– Share availability data with stakeholders.hypothetical question
– Detect security breaches.
– Plan and budget for IT upgrades.
– Reduce downtime and business losses.
Prerequisites

# yum install gd gd-devel gcc glibc glibc-common

Facebook block in Mikrotik By layer 7 protocols

Facebook block in Mikrotik router by layer 7 protocols

1. IP>Firewall>Layer7 Protocols>add(+)
 
       1.1 Layer7 Protocols
                              Name       :   Facebookblock_L7P    
                              Regexp     :   ^.+(facebook).*$                 ; ^.+(facebook |youtube ).*$

        1.2  Apply>OK

2.IP>Firewall>Filter Rules>add(+)
     
       2.1 Filter Rules>General>
     
                                 Chain                     :forward
                                 Src. Address           :192.168.1.0/24      ; LAN IP block

       
       2.2 Filter Rules>advanced>
       
                                  Layer7 Protocol    :Facebookblock_L7P

       2.3 Filter Rules>action>

                                  action     : drop

       2.4 Apply>OK

VPN : virtual private network

VPN : virtual private network : The logical connectivity between two same or different private networks from remote place

Classification:

            1.Server to Client  tunnel

            2.Server to Server tunnel

                                                1.     Server to Client  tunnel:

                                                                   -------------o------------

                                                                2. Server to Server tunnel

              2.1    Layer 2 tunnel (Same local network)
                2.2    Layer 3 tunnel  (Different networks)

2.1    Layer 2 tunnel (Same local network)

-------------o------------

  2.2   Layer 3 tunnel  (Different networks)

-------------o------------

Mikrotik Site-to-Site GRE Tunnel Configuration

Mikrotik Site-to-Site GRE Tunnel Configuration

Mikrotik Router Site-to-Site GRE Tunnel Configuration :GRE (Generic Routing Encapsulation) is tunneling protocol.GRP is cisco propitiatory protocol,it is simile to IPIP and EOIP which originally built up as stateless tunnels.GRE create a virtual point-to-point protocol link.
GRE Configuration Video

Site1:
/interface gre add name=Gre_site1 remote-address=172.16.100.2 local-address=172.16.1.2


/ip address
  add address=192.168.100.1/30 interface=Gre_site1

/ip route
  add dst-address=10.10.10.0/24 gateway=192.168.100.2


Site2:


/interface gre add name=Gre_site2 remote-address=172.16.1.2 local-address=172.16.100.2

/ip address
  add address=192.168.100.2/30 interface=Gre_site2

/ip route
  add dst-address=192.168.100.0/24 gateway=192.168.100.2

Mikrotik Script for adding 253 queues by 10 seconds:

Mikrotik Script for adding 253  queues by 10 seconds:

:for x from=2 to=254 do={/queue simple add name="User-$x" d interface=all max-limit=3M/3M target-addresses="192.168.1.$x"}

where
      Upload speed=3M
      Download speed=3M
      Client IP-address=192.168.1.0/24
 

exporting queues list
##  queuee simple
#export file=name

How to configure username and password

       DHAKA(config)#username my_username  privilege 15 secret my_password

To reset a Cisco router to factory default

To reset a Cisco router to factory default (removing the startup configuration file), perform these steps:

1.To erase the configuration file, issue the erase nvram:command. Reload the router by issuing the reload command.

2.If this does not solve the problem, attempt to break into ROM Monitor (ROMmon) by issuing the break sequence (usually Ctrland break from the Hyperterminal) from a console connection.

Refer to: Cisco Standard Break Key Combinations. You should see this ROMmon prompt:

rommon 1>

3.Change the configure register value to ignore the startup configuration by issuing theconfreg command, as shown in this example:

rommon 2> confreg 0x2142

4.To reload the router, issue the reset command, as shown in this example:

rommon 3> reset

5.After the router boots, issue the enable command at the Router > prompt. The prompt changes to Router#, indicating that the router is now in privileged mode.

6.To enter config mode, issue the config terminal command. You should now see aRouter(config)# prompt.

7.To change the configure register to recognize the startup configuration, issue theconfig-register command, as shown in this example:

Router (config)# config-register 0x2102

To break out of configuration mode, press Cntl and Z. To save the blank configuration, issue the copy-running config-startup config command.