Michael: /* Identify Open Ports */

2013-08-18T12:00:26Z

Identify Open Ports

Michael: Created page with "== View the current routing tables == There are two equivalent commands to view the current routing tables. Using the -n flag displays ip address instead of hostnames
2013-08-18T11:59:19Z

Created page with "== View the current routing tables == There are two equivalent commands to view the current routing tables. Using the -n flag displays ip address instead of hostnames <bash..."

New page
== View the current routing tables ==

There are two equivalent commands to view the current routing tables. Using the -n flag displays ip address instead of hostnames

<syntaxhighlight>
netstat -nr
route -n
</syntaxhighlight>

<syntaxhighlight>
[root@compute011 ~]# route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
192.168.0.0 0.0.0.0 255.255.255.0 U 0 0 0 ib0
172.16.0.0 0.0.0.0 255.255.0.0 U 0 0 0 eth0
169.254.0.0 0.0.0.0 255.255.0.0 U 1002 0 0 eth0
169.254.0.0 0.0.0.0 255.255.0.0 U 1005 0 0 ib0
239.0.0.0 0.0.0.0 255.0.0.0 U 0 0 0 ib0
0.0.0.0 172.16.1.1 0.0.0.0 UG 0 0 0 eth0
</syntaxhighlight>

Each Destination is a network. The default destination (0.0.0.0) refers to all other networks.

A gateway is supplied only if the gateway is not on the same network, otherwise the default gateway is 0.0.0.0.

Networks look for the route that applies by comparing its IP address to each destination in order. If there is a gateway, packets are sent to the system with that IP.

== Adding a route ==

The netstat and route commands have different uses. The route command is used to add and edit routing information in the route table.

To add a route

<syntaxhighlight>
route add default gw 192.168.122.1 #default route
route add -net 192.168.100.0 netmask 255.255.255.0 dev eth1 #routes the network through device eth1
</syntaxhighlight>

== Identify Open Ports ==

The netstat command can be used to identify open ports on the system when used with the right flags.

Running netstart -atunp will list all open ports on the system

{| class="wikitable"
|-
| Flag || Purpose
|-
|-a || Show all networks
|-
|-t || Using TCP
|-
|-u || Using UDP
|-
|-n || Using Numeric format
|-
|
|}

@@ Line 46: / Line 46: @@
 {| class="wikitable"
 | Flag  || Purpose
 |-
-|-a || Show all networks
+| a || Show all networks
 |-
-|-t || Using TCP
+| t || Using TCP
 |-
-|-u || Using UDP
+| u || Using UDP
 |-
-|-n || Using Numeric format
+| n || Using Numeric format
 |-
 |}