How to Use the Command 'frpc' (with Examples)

frpc is a command-line tool used to connect to an frps server, enabling the proxying of connections from the current host. It is part of the frp (Fast Reverse Proxy) suite, which provides high-performance and reliable reverse proxy tools, useful in a variety of networking applications such as connecting to devices behind NAT or firewalls. The tool is highly customizable and supports many configuration options that can be specified through configuration files, typically in .ini or .toml formats.

Use Case 1: Starting the Service with the Default Configuration File

Code:

frpc

Motivation:

This command is the simplest way to start frpc when the configuration file is named frps.ini and is located in the current working directory. Using the default configuration allows users to quickly initiate the service without specifying additional parameters, making it a convenient method for testing, demonstration, or environments where configurations are standardized.

Explanation:

• frpc: Invoking this on its own tells the tool to start using frps.ini in the current directory as its configuration file. This assumes that the user has a correctly configured file ready and set in place.

Example Output:

2023/10/10 10:00:00 [INFO] [service.go:288] [abcd] start proxy success
2023/10/10 10:00:00 [INFO] [control.go:445] [abcd] [udp] proxy: 127.0.0.1:8080 established

Use Case 2: Starting the Service with a TOML Configuration File

Code:

frpc -c ./frps.toml

Motivation:

This use case is designed for users who prefer or require the TOML format for configuration files. TOML, being more readable and structured than traditional INI files, may be favored in complex setups or when detailed configurations are necessary. Specifying the file with -c allows flexibility in configuration file formats and names.

Explanation:

• -c: This flag specifies the configuration file to use.
• ./frps.toml: Defines the path to the TOML configuration file, assumed to be in the current directory. It allows frpc to use settings defined in a structured TOML file.

Example Output:

2023/10/10 10:05:00 [INFO] [service.go:288] [efgh] start proxy success
2023/10/10 10:05:00 [INFO] [control.go:445] [efgh] [tcp] proxy: 127.0.0.1:9090 established

Use Case 3: Starting the Service with a Specific Configuration File

Code:

frpc -c /path/to/your/config/file.ini

Motivation:

Sometimes different environments or projects require unique configurations, and you might have several different configuration files. This usage scenario is beneficial for developers who continuously switch between different server setups, products, or environments and need to quickly deploy the correct settings.

Explanation:

• -c: Again indicates the configuration option.
• /path/to/your/config/file.ini: The absolute or relative path to the configuration file you wish to use. It can be in .ini or .toml format, providing flexibility to the user.

Example Output:

2023/10/10 10:10:00 [INFO] [service.go:288] [ijkl] start proxy success
2023/10/10 10:10:00 [INFO] [control.go:445] [ijkl] proxy running at 192.168.1.10:7070

Use Case 4: Verifying the Configuration File

Code:

frpc verify -c /path/to/config/file

Motivation:

Prior to deploying frpc, it is crucial to ensure that the configuration file does not contain errors that could lead to failures or unexpected behavior. Verifying a configuration file can save time during deployment and prevent unnecessary troubleshooting.

Explanation:

• verify: This command checks the syntax and validity of the configuration file without starting the service.
• -c: Specifies the configuration to be verified.
• /path/to/config/file: Path to the configuration file to verify. It checks whether the settings conform to expected parameters and formats.

Example Output:

configuration file is valid

Use Case 5: Generating Autocompletion Script

Code:

frpc completion bash

Motivation:

Command-line completion scripts enhance usability by providing users with command suggestions while typing, reducing errors and speeding up workflow. Autocompletion is particularly helpful for users who often work in terminal environments with complex commands.

Explanation:

• completion: Indicates that the user wishes to generate an autocompletion script.
• bash: Specifies the shell type to which the generated script should apply. Other supported shells are fish, powershell, and zsh.

Example Output:

# bash completion script example for frpc
...

Use Case 6: Displaying the Version

Code:

frpc -v

Motivation:

Checking the version of an installed application is a basic but essential practice to ensure compatibility with other components and to keep the software up to date. This information helps in diagnosing issues or following documentation versions.

Explanation:

• -v: The shorthand for --version, this flag prints the version of the frpc tool that is currently installed.

Example Output:

frpc version 0.37.1

Conclusion

The frpc command is a versatile tool for setting up reverse proxies in a network by connecting to an frps server. Through the various use cases detailed above, users can efficiently manage configurations, verify settings, and enhance their command-line experience, ensuring seamless operation and deployment in diverse environments.