Determining Public IP Address

Sometimes, it is just the simplest of things. An admin asked the other day what our Internet egress address was. I told him that he could use his browser to find out. However, he was dealing with a remote host, which had a different public address. A couple sites you can use to easily grab your public address from the command line are ifconfig.me and icanhazip.com.

  [bandarji ~]$ curl http://ifconfig.me/ ; curl http://icanhazip.com/
  200.99.99.200
  200.99.99.200
  [bandarji ~]$

These can also be used within bash quite easily.

  [bandarji ~]$ egress="`curl http://ifconfig.me/ 2> /dev/null`" ; echo $egress
  200.99.99.200
  [bandarji ~]$

Load Balancing Without a Load Balancer

Application delivery controllers perform a great service to direct traffic to servers which should handle client requests. Decisions on where to send information can be based on a variety of factors. Like their kid brother, the server load balancer, they present a virtual service address, linked to more than one backend system. By monitoring services on individual servers, the ADC or SLB drops unreliable services from pools to ensure high availability. Further, they divvy requests between servers which can answer them, balancing a load which might be higher than one system could accept.

There are times when you don't need the delivery options an ADC can provide, and even an SLB solution might not make sense. A tandem set of appliances for each local area network where servers reside is expensive to purchase and maintain vendor support. They also require power and use precious rack space. If a server load balancer is all you need to ensure service availability while dividing load, perhaps a different solution could do the job.

Hindi Support For Linux

Ever visited a web site, like the one pictured above, and saw a bunch of (Unicode) blocks instead of the text you expected? Install support for the language you want on your Linux host, just like I did for the above-pictured Punjabi.

Linux Host-to-Host IPSEC

Sometimes, you want to encrypt all IP traffic between two Linux hosts. An easy way to do this with Red Hat Linux is to use IPSEC. While there are many applications which are encrypted, such as secure shell or even transport layer security and secure sockets layer over usually-unencrypted applications, IPSEC works at a lower level. IPSEC therefore can work regardless of the application and encrypts all IP communication.