A beautiful command-line tool for parsing CIDR subnet masks and checking IP address membership, built with Go.

• Parse CIDR Notation - Display comprehensive network information including:

  • Network address and subnet mask
  • Broadcast address
  • IP range (total and usable)
  • Host counts (total and usable)

• IP Membership Checking - Verify if an IP address belongs to one or more CIDR ranges

• Config File Support - Load default CIDR ranges from ~/.cidr file

• Beautiful Output - Color-coded terminal output with clear visual hierarchy using Lipgloss

go install github.com/trahma/cidr@latest

Or build from source:

git clone https://github.com/trahma/cidr
cd cidr
go build -o cidr .

After installing with go install, you need to ensure GOPATH/bin is in your PATH.

echo $PATH | grep -q "$(go env GOPATH)/bin" && echo "✓ Already in PATH" || echo "✗ Not in PATH"

If not already in PATH, add it to your shell configuration:

Bash (~/.bashrc):

echo 'export PATH="$PATH:$(go env GOPATH)/bin"' >> ~/.bashrc
source ~/.bashrc

Zsh (~/.zshrc):

echo 'export PATH="$PATH:$(go env GOPATH)/bin"' >> ~/.zshrc
source ~/.zshrc

Fish (~/.config/fish/config.fish):

fish_add_path (go env GOPATH)/bin

cidr --help

If you see the help output, you're all set!

cidr 192.168.1.0/24

Output:

CIDR Information

CIDR: 192.168.1.0/24
Network Address: 192.168.1.0
Subnet Mask: 255.255.255.0
Broadcast Address: 192.168.1.255

IP Range: 192.168.1.0 - 192.168.1.255
Usable IPs: 192.168.1.1 - 192.168.1.254

Total Hosts: 256
Usable Hosts: 254

cidr 192.168.1.0/24 --check 192.168.1.50

cidr --check 192.168.5.10

This will check the IP against all CIDR ranges defined in your ~/.cidr config file.

Create a ~/.cidr file with your default CIDR ranges (one per line):

# Private network ranges
192.168.0.0/16
10.0.0.0/8
172.16.0.0/12

Lines starting with # are treated as comments and ignored.

You can also specify a custom config file:

cidr --config /path/to/custom.cidr --check 192.168.1.1

Flags:
  -c, --check string    Check if an IP address is within the CIDR range
  -f, --config string   Path to .cidr config file (defaults to ~/.cidr)
  -h, --help            help for cidr

Parse a large network:

cidr 10.0.0.0/8

Check an IP against multiple ranges:

cidr --check 172.16.5.100

Parse with custom config file:

cidr --config ./networks.cidr --check 192.168.1.1

• Cobra - CLI framework
• Lipgloss - Terminal styling

MIT