A script that takes two files--a set of IPs and a set of Subnet--and shows which IPs are in which subnets

check_ips_against_subnets.sh

#!/bin/bash                                                          
                                                                     
if [ "$#" -lt 2 ]; then                                              
  echo "Usage: $0 <IP_FILE> <CIDR_FILE>"                             
  exit 1                                                             
fi                                                                   
                                                                     
IP_FILE=$1                                                           
CIDR_FILE=$2                                                         
                                                                     
# Read IPs and subnets into arrays                                   
mapfile -t ips < "$IP_FILE"                                          
mapfile -t subnets < "$CIDR_FILE"                                    
                                                                     
# Function to check if an IP is in a subnet                          
check_ip_in_subnet() {                                               
  local ip=$1                                                        
  local subnet=$2                                                    
  local temp_subnet_file=$(mktemp)                                   
                                                                     
  echo "$subnet" > "$temp_subnet_file"                               
  if echo "$ip" | iprange -1 "$temp_subnet_file" &>/dev/null; then   
    rm "$temp_subnet_file"                                           
    return 0                                                         
  else                                                               
    rm "$temp_subnet_file"                                           
    return 1                                                         
  fi                                                                 
}                                                                    
                                                                     
# Check each IP against the subnets                                  
for ip in "${ips[@]}"; do                                            
  found=0                                                            
  for subnet in "${subnets[@]}"; do                                  
    if check_ip_in_subnet "$ip" "$subnet"; then                      
      echo "IP address $ip is in subnet $subnet"                     
      found=1                                                        
      break                                                          
    fi                                                               
  done                                                               
  if [ "$found" -eq 0 ]; then                                        
    echo "IP address $ip is not in any of the subnets"               
  fi                                                                 
done