SFTP file system

This file system provides an implementation for the file system based on the SFTP protocol using SSH.NET library.

Usage

Password authentication:

var address = "address";
var username = "username";
var password = "password";

using var fileSystem = TagBites.IO.Sftp.SftpFileSystem.Create(address, username, password);
// ... using like standard file system

Private key authentication:

var keyFile = new PrivateKeyFile("path/to/private-key");

using var fileSystem = TagBites.IO.Sftp.SftpFileSystem.Create(address, username, keyFile);
// ... using like standard file system

Remember to use using statement or call Dispose method after usage.

Host key verification

By default - the same as in SSH.NET itself - the server’s host key is trusted without verification. To pin an expected key, pass a SftpConnectionConfig with ExpectedHostKeyFingerprintSha256 set to the fingerprint reported by the server (e.g. via ssh-keyscan or ssh -o FingerprintHash=sha256); the connection is rejected if the presented key doesn’t match:

var connectionConfig = new SftpConnectionConfig(address, username, password)
{
    ExpectedHostKeyFingerprintSha256 = "ohD8VZEXGWo6Ez8GSEJQ9WpafgLFsOfLOtGGQCQo6Og",
    ConnectionTimeout = TimeSpan.FromSeconds(10)
};

using var fileSystem = TagBites.IO.Sftp.SftpFileSystem.Create(connectionConfig);
// ... using like standard file system

Limitations

• The SFTP protocol has no server-side recursive listing, so recursive listing is performed by walking subdirectories one by one instead of a single call.
• Direct stream access (OpenRead/OpenWrite) is read-only, same as the FTP file system.
• Like FTP, S3, Dropbox and Google Cloud Storage, this file system does not support real change watching - see change notifications and watching for what CreateWatcher() does and doesn’t detect here.

Capabilities

• Synchronous and asynchronous operations.
• Reports permissions from the server, so CanRead and CanWrite reflect the remote account.
• Metadata: last write time only.
• The host key is not verified unless ExpectedHostKeyFingerprintSha256 is set - see security policy.

Full implementation on github: TagBites.IO.Sftp.