tr.sh

tr.sh is a small Bash TCP reachability checker. It scans one or more hosts against one or more ports and reports which connections are open or closed.

It is useful for quick checks when you do not need a full port scanner like nmap.

Features

• Supports IPv4 addresses, hostnames, and localhost.
• Supports comma-separated host lists.
• Supports last-octet IPv4 ranges:
  • 192.168.1.5-10
  • 192.168.1.5-192.168.1.10
• Supports comma-separated ports and port ranges:
  • 22,80,443
  • 8000-8010
• Uses Bash /dev/tcp for TCP connection checks.
• Avoids unsafe interpolation of user input into shell code.
• Detects timeout or gtimeout.
• Supports interactive prompts or command-line options.
• Includes colored output, --no-color, and NO_COLOR support.
• Includes --open-only for cleaner output.
• Prints a scan summary.

Requirements

• Bash 4.x or newer.
• Linux, macOS, or another environment where Bash supports /dev/tcp.
• timeout from GNU coreutils.

On most Linux systems, timeout is already available.

On macOS, install GNU coreutils:

brew install coreutils

The script automatically uses gtimeout if timeout is not available.

Installation

git clone https://github.com/yourusername/yourrepo.git
cd yourrepo
chmod +x tr.sh

Usage

Interactive mode:

./tr.sh

Command-line mode:

./tr.sh --hosts 192.168.1.1,192.168.1.5-10 --ports 22,80,443

Short options:

./tr.sh -H localhost,example.com -p 80,443 -t 2

Show only open ports:

./tr.sh -H 192.168.1.1-20 -p 22,80,443 --open-only

Disable colors:

./tr.sh -H example.com -p 80,443 --no-color

Options

Option	Description
-H, --hosts	Comma-separated hosts, IPs, or IPv4 ranges.
-p, --ports	Comma-separated ports or port ranges.
-t, --timeout	Timeout per connection in seconds. Default: 1.
--open-only	Print only open results.
--no-color	Disable colored output.
-h, --help	Show help.
-v, --version	Show version.

Host Input Examples

Single IPv4 address:

192.168.1.10

Multiple IPv4 addresses:

192.168.1.10,192.168.1.20

Short last-octet range:

192.168.1.5-10

Full last-octet range:

192.168.1.5-192.168.1.10

Hostnames:

localhost,example.com

Port Input Examples

Single port:

22

Multiple ports:

22,80,443

Port range:

8000-8010

Mixed:

22,80,443,8000-8010

Example Output

Scanning 2 host(s), 3 port(s), 6 check(s), timeout 1s...

OPEN  - localhost:22
CLOSED - localhost:80
CLOSED - localhost:443
OPEN  - example.com:80
OPEN  - example.com:443
CLOSED - example.com:8080

Summary: 3 open, 3 closed, 6 total

Notes

This script checks TCP connectability only. It does not identify services, perform UDP scans, detect operating systems, or replace a full scanner such as nmap.

Use it only on systems and networks you own or have permission to test.

License

GPL-3.0-or-later. See https://www.gnu.org/licenses/gpl-3.0.html.