I just borrowed Linux Networking Cookbook from the library. I’m reading chapter 5 Building a VoIP Server with Asterisk page 128. I’m stuck. I installed the Development Tools package group. Now, I need to download the current releases of the three main source tarballs from Asterisk.org into the /usr/src directory. I see this:
[root@asterisk1 src]# wget ftp.digium.com/pub/asterisk/rele … 4.4.tar.gz
ftp.digium.com/pub/asterisk/rele … 4.3.tar.gz
ftp.digium.com/pub/asterisk/rele … 4.0.tar.gz
the error message i get is, failed: Name or service not know. wget: unable to resolve host addrress “ftp.digium.com”
How do i do this? Any suggestions. 
