00-README.adoc

README

This is a CentOS-themed /etc/issue w/ hooks to update IP address and OS release upon ifup/ifdown. My motivation was that I was tired of logging into an otherwise headless box just to find the IP of the system so I can SSH to it.

Note	The issue.in file actually contains control characters to do the color in the text. The easiest way to preserve that is to clone this gist and run the install.sh script w/ sudo, which will copy the file and set the SELinux contexts.

Screenshot on console:

Tip	You may also wanted to change /etc/ssh/sshd_config to point to /etc/motd instead of /etc/issue, but this is just user preference.

90-issue-update

#!/bin/bash
# 90-issue-update
# Description: Updates /etc/issue using template /etc/issue.in and
#              values from system at time of interface up

IF=$1
STATUS=$2

function update_issue() {
   OS_RELEASE=$(cat /etc/redhat-release);
   IP_ADDR=$(ip route get 255.255.255.255 | awk '{print $6 " ("$4")"; exit}')
   cat /etc/issue.in | sed "s/{{OS_RELEASE}}/${OS_RELEASE}/;s/{{IP_ADDR}}/${IP_ADDR}/" > /etc/issue
   
   # Reset gettys where a user is not logged in
   GETTYS=$(systemctl list-units | grep "getty@" | grep -vE "$(who | awk '{ print $2 }'|paste -sd'|' )" | awk '{print $1}'|paste -s)
   systemctl restart $(GETTYS)
}

if [ "$IF" <> "lo" ]
then
  case "$2" in
    up)
      logger -s "NM Script up triggered"
      update_issue
      ;;
    down)
      logger -s "NM Script down triggered"
      update_issue
      ;;
    *)
      ;;
  esac
fi

install.sh

#!/bin/sh
# Need to set proper SELinux contexts, we'll borrow from existing
# Need to run this with `sudo`

# Copy files from current directory
cp issue.in /etc/issue.in
cp 90-issue-update /etc/NetworkManager/dispatcher.d/

# Update SELinux contexts
chcon --reference /etc/issue{,.in}
chcon --reference /etc/NetworkManager/dispatcher.d/{11-dhclient,90-issue-update}

issue.in

                   ..                   
                 .PLTJ.                 
                <><><><>                
       KKSSV' 4KKK LJ KKKL.'VSSKK        Hostname:  \n
       KKV' 4KKKKK LJ KKKKAL 'VKK        OS:        {{OS_RELEASE}} 
       V' ' 'VKKKK LJ KKKKV' ' 'V        Kernel:    \s
       .4MA.' 'VKK LJ KKV' '.4Mb.        Build:     \v
     . KKKKKA.' 'V LJ V' '.4KKKKK .      IP Addr:   {{IP_ADDR}} 
   .4D KKKKKKKA.'' LJ ''.4KKKKKKK FA.   
  <QDD ++++++++++++  ++++++++++++ GFD>  
   'VD KKKKKKKK'.. LJ ..'KKKKKKKK FV    
     ' VKKKKK'. .4 LJ K. .'KKKKKV '     
        'VK'. .4KK LJ KKA. .'KV'         Date:  \d
       A. . .4KKKK LJ KKKKA. . .4        Time:  \t 
       KKA. 'KKKKK LJ KKKKK' .4KK        Users: \U
       KKSSA. VKKK LJ KKKV .4SSKK       
                <><><><>                 
                 'MKKM'                  
                   ''  

screenshot.png