Linux Routing table

-
We can check current Linux route table with netstat command

# netstat -rn
Kernel IP routing table
Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface
0.0.0.0         12.96.176.1     0.0.0.0         UG        0 0          0 eth2
5.72.185.0      0.0.0.0         255.255.255.0   U         0 0          0 eth0
12.96.154.0     0.0.0.0         255.255.255.0   U         0 0          0 eth1
12.96.176.0     0.0.0.0         255.255.255.0   U         0 0          0 eth2
13.122.288.72   5.72.185.1      255.255.255.240 UG        0 0          0 eth0
127.0.0.0       0.0.0.0         255.0.0.0       U         0 0          0 lo
135.188.0.0     5.72.185.1      255.255.0.0     UG        0 0          0 eth0
135.188.45.153  5.72.185.1      255.255.255.255 UGH       0 0          0 eth0
174.65.146.0    5.72.185.1      255.255.255.0   UG        0 0          0 eth0
169.254.0.0     0.0.0.0         255.255.0.0     U         0 0          0 eth0


 Q: How to add a new route?

To add a single host destination:
# route add $Host_IP gw $Gateway

e.g:
# route add 12.153.4.22 gw 6.64.215.1

To add a network destination:
# route add –net $Network_IP netmask $MASK gw $Gateway

e.g:
# route add -net 12.153.4.0 netmask 255.255.255.248 gw 6.64.215.1
Q: How to delete route?

# route del –net $Network_IP netmask $MASK gw $Gateway

Q: How to check the default gateway?

In routing table, the row start with 0.0.0.0 has gateway IP which in this example is 12.96.176.1

# netstat -rn
Kernel IP routing table
Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface
0.0.0.0         12.96.176.1     0.0.0.0         UG        0 0          0 eth2
5.72.185.0      0.0.0.0         255.255.255.0   U         0 0          0 eth0
12.96.154.0     0.0.0.0         255.255.255.0   U         0 0          0 eth1
12.96.176.0     0.0.0.0         255.255.255.0   U         0 0          0 eth2
13.122.288.72   5.72.185.1      255.255.255.240 UG        0 0          0 eth0
127.0.0.0       0.0.0.0         255.0.0.0       U         0 0          0 lo
135.188.0.0     5.72.185.1      255.255.0.0     UG        0 0          0 eth0
135.188.45.153  5.72.185.1      255.255.255.255 UGH       0 0    
      0 eth0
174.65.146.0    5.72.185.1      255.255.255.0   UG        0 0          0 eth0
169.254.0.0     0.0.0.0         255.255.0.0     U         0 0          0 eth0

and finally to set default gateway we can use following command:

# route add default gw 192.168.1.254 eth0


Comments

Post a comment

Popular posts from this blog

Running Docker Wildfly/JBoss Application Server in Debug mode via Eclipse

-
I have recently built the whole Development Environment of Java Enterprise Edition (J2EE) project on multiple Docker containers. It has saved the hassle of setting up a dev env for new developers. All it takes to setup the environment is to clone our github repositories and run the Docker images. I will explain the setup in a future post. Build Wildfly Docker Image with Debugging Enabled So basically in order to run the Wildfly in debug mode, we need to add --debug  flag to the Wildfly standalone.sh  startup script. Also we need to expose port 8787  in our image as it's the default port for Wildfly JVM debug mode. 1. Create or change your Wildfly Dockerfile as follows: $ cat Dockerfile FROM jboss/wildfly: 10.0 . 0 .Final EXPOSE 8787 CMD [ "/opt/jboss/wildfly/bin/standalone.sh" , "-b" , "0.0.0.0" , "-bmanagement" , "0.0.0.0" , "--debug" ] 2. Build and tag the image: $ docker build -t wildfly-debug . 3.
Read more

Building RPM OpenSSH 7.1p1 on RHEL/CentOS 6.5

-
After I've implemented the OpenVAS vulnerability assessment system, I've made a complete vulnerability testing on the environment for both Linux and Wintel servers. The result for the all Linux servers were Red :) Severity 10.0(High). The reason was the OpenSSH version 5. Test result: High  (CVSS: 8.5) NVT: OpenSSH Multiple Vulnerabilities (OID: 1.3.6.1.4.1.25623.1.0.806052) Product detection result: cpe:/a:openbsd:openssh:5.3 by SSH Server type and version (OID: 1.3.6.1.4.1.25623.1.0.10267) Summary This host is running OpenSSH and is prone to multiple vulnerabilities. Vulnerability Detection Result Installed version: 5.3 Fixed version: 7.0 Impact Successful exploitation will allow an attacker to gain privileges, to conduct impersonation attacks, to conduct brute-force attacks or cause a denial of service. Impact Level: Application Solution Upgrade to OpenSSH 7.0 or later. For updates refer to http://www.openssh.com Affected Software/OS OpenSSH vers
Read more