DNS Helper

Again, awesome tool folks!

It seems there're at least a couple minor bugs, however:

1. b.root-servers.net seems to be missing its corresponding IPv6 address (i.e., 2001:500:84::b). (This is consistent for at least RHEL 6 and RHEL 7 scripts.)

2. Toward the end of all the scripts I read through, we have these blocks of code, which differ slightly based on RHEL version:

   For RHEL 6:

   echo "Start named service, and set it to run on startup"
   service named status
   if [ $? == 0 ]; then
     service named restart
   else
     service named start
   fi
   chkconfig named on
   
   if [ $? -ne 0 ]; then
    echo "Can't start named service, make sure you have the right permission and SELinux setting"
    exit 1
   fi
   

   For RHEL 7:

   echo "Start named service, and set it to run on startup"
   systemctl status named-chroot
   if [ $? == 0 ]; then
     systemctl restart named-chroot
   else
     systemctl start named-chroot
   fi
   systemctl enable named-chroot
   
   if [ $? -ne 0 ]; then
    echo "Can't start named service, make sure you have the right permission and SELinux setting"
    exit 1
   fi
   

   The bug occurs in the sequence from enabling the service (after the first if statement) to testing for a non-zero exit status of (re)starting named-chroot in the second if statement. For the second if statement to evaluate a valid test, the exit status will need to be captured for whichever of the consequent- or alternate-consequent lists are executed in the first if statement (i.e., restarting and starting named-chroot, respectively).

And here're a few suggestions that may help:

1. Scripts don't have any comments ID'ing the key/initial parameters selected (e.g., RHEL Version, DNS Server Type). While the descriptive file name of the scripts is useful, it may be helpful to users to have that documentation near the head of their script(s).

2. Scripts don't check for or advise on execution as root. As this is a tool produced and owned by Red Hat, and the helper scripts essentially need rootly powers to complete successfully, it seems something should be noted on the matter for users who may not be fully aware of the risks of running a scripted program they got from the Internet as root. (Helper scripts pulled down from Red Hat is an exception to that rule, of course, but these scripts offer a great opportunity to advise against such things as root in most other cases.)

3. As SELinux is enforcing by default in RHEL, their should probably be some check on its status and subsequent flow based on the result (of the status). For example, in the script produced for configuring the slave server(s), there are these four lines toward the end of the script:

   # chown named:named /var/named/slaves
   # chmod 755 /var/named/slaves
   # semanage fcontext -a -t named_cache_t '/var/named/slaves(/.*)?'
   ls -ldZ /var/named/slaves
   

   While the fourth line may serve as a fair reminder that further action may be needed as it relates to SELinux contexts (and for those who understand what they're looking at), it may be more helpful for all users if such conditional behavior is also automated.

~D