Installation Problem

[achuth]

Sir,
I have ubuntu 11.10.

The following is my problem while installing server tools

sudo apt-get install yp-tools ypbind ypserv portmap
Reading package lists... Done
Building dependency tree
Reading state information... Done
Note, selecting 'rpcbind' instead of 'portmap'
E: Unable to locate package yp-tools
E: Unable to locate package ypbind
E: Unable to locate package ypserv


Please suggest a solution

[QIII]

Are you sure those packages are in the Ubuntu repositories?

Where did you learn about them?

Can you find them in the Software Center?