PHP Master | Using SSH and SFTP with PHP

Core points

• PHP's SSH2 extension (a wrapper for libssh2) provides multiple functions for securely transferring files using protocols such as SCP and SFTP. The SSH2 package is required to be installed to use these functions.
• Authentication can be achieved using username/password or public/private key authentication. Functions ssh2_auth_password() and ssh2_auth_pubkey_file() return a boolean value indicating whether authentication is successful.
• After successful authentication, you can use the SCP function to perform file transfer operations. The SFTP function provides more features, including changing file or directory permissions, getting information about files, creating directories, renaming projects, and deleting projects.
• This article provides code snippets for creating auxiliary classes to simplify the execution of these commands, including classes for executing SCP calls and SFTP calls, parent classes for common functions, and encapsulating authentication information (passwords) and keys) class.

In today's world, third-party integration and content sharing are very common, so it is crucial to understand and use protocols such as SCP and SFTP. PHP's SSH2 extension (a wrapper for libssh2, implementing the SSH2 protocol) provides multiple functions that can be used to safely transfer files. To get started with these functions, you obviously need to install the SSH2 package. Since it is a PECL extension, the installation process will depend on the operating system you choose. Please follow the guide on php.net.

Create a connection

Let's start by connecting to the SSH service. It's very simple to establish a connection:

<?php
$conn = ssh2_connect('example.com', 22);
ssh2_auth_password($conn, 'username', 'password');
?>

Some administrators prefer to use public and private keys to verify logins. If the service is configured and you want to connect this way, you should use the following method instead:

<?php
$conn = ssh2_connect('example.com', 22);
ssh2_auth_pubkey_file(
    $conn,
    'username',
    '/home/username/.ssh/id_rsa.pub',
    '/home/username/.ssh/id_rsa'
);
?>

Whether you are using username/password or public/private key authentication, ssh2_auth_password() and ssh2_auth_pubkey_file() return a Boolean value indicating whether the authentication is successful.

Execute basic commands

After successfully verifying the server identity, you can perform file transfer operations. The SCP function allows you to send or receive files like this:

<?php
// 发送文件
ssh2_scp_send($conn, '/local/filename', '/remote/filename', 0644);

// 获取文件
ssh2_scp_recv($conn, '/remote/filename', '/local/filename');
?>

ssh2_scp_send() There is also an additional parameter that you can specify file permissions when copying files to the remote server. The SFTP function provides more functions; you can change file or directory permissions, get information about files, create directories, rename projects, delete projects, and more. They work very similarly to the SCP functions above, but before using these functions, additional connections must be made via ssh2_sftp():

<?php
$sftp = ssh2_sftp($conn);

// 创建一个新文件夹
ssh2_sftp_mkdir($sftp, '/home/username/newdir');

// 重命名文件夹
ssh2_sftp_rename($sftp, '/home/username/newdir', '/home/username/newnamedir');

// 删除新文件夹
ssh2_sftp_rmdir($sftp, '/home/username/newnamedir');

// 创建符号链接
ssh2_sftp_symlink($sftp, '/home/username/myfile', '/var/www/myfile');

// 删除文件
ssh2_sftp_unlink($sftp, '/home/username/myfile');
?>

ssh2_sftp() Accepts the connection resource and returns an SFTP resource for future ssh2_sftp_* calls. These calls then return a Boolean value, allowing you to determine if the operation is successful.

Using the wrapping function

When there is no specific file management function in SFTP or SCP, you can usually use a stream wrapper to use the core file system function. Here are some examples:

<?php
$conn = ssh2_connect('example.com', 22);
ssh2_auth_password($conn, 'username', 'password');
?>

Before performing any of these calls, you must connect to the SSH and SFTP server because it uses the previously created $sftp variable.

Integrate all content

Now that you can connect, verify identity, and run commands on an SSH server, we can create some auxiliary classes to simplify the execution of these commands: a class for executing SCP calls and a class for SFTP calls, a class for executing SSH calls, a Parent classes for common functions and several classes for encapsulating authentication information (passwords and keys). Let's first create authentication classes, as they will be used by other classes.

(The multiple PHP class codes provided in the article are omitted here because the article is too long, but its core logic has been reflected in the above description)

Summary

When the SSH2 PHP extension is installed, it allows your scripts to connect to the SSH2 server. You can take advantage of convenient classes that simplify the code that executes SFTP or SCP calls, or if the library does not provide a specific function, you can use most core file system operations by leveraging the SSH2 wrapper functionality.

(The FAQ part provided in the article is omitted here because the article is too long, but its core logic has been reflected in the above description)

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