Personally, I prefer avoiding the PECL SSH2 extension. My preferred approach involves phpseclib, a pure PHP SFTP implementation. Here's an example with phpseclib 2.0 [requires composer]:
Here's that same example with phpseclib 1.0:
One of the big things I like about phpseclib over the PECL extension is that it's portable. Maybe the PECL extension works on one version of Linux but not another. And on shared hosts it almost never works because it's hardly ever installed.
phpseclib is also, surprisingly, faster. And if you need confirmation that the file uploaded you can use phpseclib's built-in logging as proof.
Download and Extract the PHP library to the same directory level where the PHP script is to be used for connecting to a remote server via SFTP: //sourceforge.net/projects/phpseclib Notes:
- phpseclib has pretty much zero server requirements. So long as the server supports PHP it’ll work.
- ibssh2, in contrast, has to be installed on the server for it to work and a lot of servers don’t have it installed.
IF it is installed you’re not going to need to include any additional files [whereas with phpseclib you will have to include them but that’s a big IF.
SFTP is a standard and secure protocol through which parties can safely transfer and share data and files. In any case, engaging with an SFTP server programatically can be challenging. In the following post, we’ll build a full fledged PHP based SFTP client, step by step, so that by the end of the guide, you’ll be able to do it all on your own!
Requirements
First and foremost, you'll need an SFTP server to connect to. If you don't have one, you can get an SFTP endpoint on SFTP To Go in less than 30 seconds.
PHP doesn’t come bundled with the SFTP libraries from the get-go, so we’ll need to install the required library ssh2 using PECL. The library relies on libssh2, so you must ensure that it is first installed on your machine. For example, on Ubuntu machines, run the following:
$ apt-get install libssh2-1-dev
$ pecl install -a ssh2-1.3
In accordance with the 12 factor app cloud development methodology, you should explicitly define your app’s dependencies, which would make our composer.json file look like this:
{
"require": {
"ext-ssh2": "*"
}
}
Now the real fun begins!
Creating and dropping SFTP connections
We’ll begin by creating a new class that encapsulates the functionality required for our SFTP client. The public methods we first add allow us to connect to the server using either password authentication or key authentication, and provide the means to disconnect an existing session.
connect-class.phpTo put our brand new methods to use, we’ll add a main function that instantiates our class and calls the auth_password
function to start a connection, as well as close the connection with the disconnect
function immediately after. We’ll use the environment variable SFTPTOGO_URL
to obtain all the required information for connecting to an SFTP server in a URI format: sftp://user:password@host
. Within our main function, the variable is parsed to
extract the username, password, host and optional port.
connect-main.phpListing Files
Now that we have set up a successful connection, we can add a function to our class and use it to list files on the remote SFTP server. The listFiles
function takes a $remote_dir
argument and returns an array of file names, along with their size and modification timestamp. To call the function, simply pass a path [you can start with
.
to traverse the current directory content] and then process the array you get.
listfiles.phpUpload File
Now it’s time to upload a file. Use the uploadFile
function and pass two arguments: the path to the local file to upload and the target remote path. A function call would look like this: $client->uploadFile["./local.txt", "./remote.txt"];
uploadfile.phpDownload File
Last
but not least: Use the downloadFile
function to download a file. Pass the path to the remote file and a local path in which the downloaded file will be stored, to the function. You would call the function like this: $client->downloadFile["./remote.txt", "./download.txt"];
downloadfile.phpSFTP To Go with maximum security and reliability
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The Whole Thing
That’s it! If
you would like to run the entire program from start to finish, copy the following code and save it as main.php
:
main.phpTo run the code, use the command:
php main.php
You can also clone our repo or check out more code samples on Github.