IP Script

[DeadBeet]

I'm trying to write a script for work for provisioning servers. It has a few questions and what not.

One of the questions: What is the network IP
and another is What is the block /29, /28 etc.

If they provide the network and the block you can figure out the gateway, and usable IPs

Is there a way to have /bin/sh configure the IPs with just that information? So if they provide 127.0.0.1/29 it will calculate 127.0.0.1 is the network 127.0.0.2 is the gateway and 127.0.0.3-127.0.0.7 are usable. However, it can't use the ipcfg-eth0-range0 method because Plesk doesn't like it.

Is this possible?

Thanks!

[nmset]

you can figure out the gateway

No, it's provided by the network administrator.

The following link and many other resources on the net may help you.
Network Calculators

Your 127.0.0.0 network is not the best example as it refers to a loopback network.

Loopback | Ask.com Encyclopedia

[DeadBeet]

I know how to calculate it. But I want to teach the script so it does it. Is it possible?

[blinky]

Not fully tested. might be a starting point?
You will have to extend it to more site specific.

#!/bin/bash

given_address="127.5.45.17/21"

read a b c d << EOF
`echo $given_address | cut -d "/" -f 1 | tr "."  " "`
EOF

i=`echo $given_address | cut -d "/" -f 2`

address[0]=${a}
address[1]=${b}
address[2]=${c}
address[3]=${d}

hexsum[0]=0
hexsum[1]=1
hexsum[2]=3
hexsum[3]=7
hexsum[4]=15
hexsum[5]=31
hexsum[6]=64
hexsum[7]=127
hexsum[8]=255

j=0
for j in {0..3}
do
  mask[j]=0
done

j=0
while ( true )
do
  if [ $i -gt 8 ] 
  then
    mask[${j}]=${hexsum[8]}
    i=$((i-8))
  else
    mask[${j}]=$((hexsum[8]^hexsum[8-i]))
    break
  fi
  
  j=$((j+1))
done

j=0
for j in {0..3}
do
  network[j]=$((address[j]&mask[j]))
done

echo "network   = ${network[0]}.${network[1]}.${network[2]}.${network[3]}"
echo "mask      = ${mask[0]}.${mask[1]}.${mask[2]}.${mask[3]}"
echo "broadcast = $((network[0] + ~mask[0]&255)).$((network[1] + ~mask[1]&255)).$((network[2] + ~mask[2]&255)).$((network[3] + ~mask[3]&255))"
echo "first     = ${network[0]}.${network[1]}.${network[2]}.${network[3]+1}"
echo "last      = $((network[0] + ~mask[0]&255)).$((network[1] + ~mask[1]&255)).$((network[2] + ~mask[2]&255)).$((network[3] + ~mask[3]&255 -1))"

[blinky]

Also have a look at ipcalc (part of initscripts in fedora)

eg.

[guest@fwall tmp]$ ipcalc -n -b -m  127.0.0.1/29
NETMASK=255.255.255.248
BROADCAST=127.0.0.7
NETWORK=127.0.0.0