&reftitle.setup;
&reftitle.required;

The OpenSSL and libssh2 libraries are required. Ensure that the development libraries are installed, where a typical package name might be `openssl-dev`.

Version 1.2 or newer of the libssh2 library is required, although it's possible newer releases of pecl/ssh2 may require newer versions (see the release notes).

The `ssh2_auth_agent` function will only be available with libssh >= 1.2.3.

support for `stream_set_timeout` to channel streams will only be available with libssh >= 1.2.9.

Libssh2 comes in two flavours: gcrypt or openssl. Some Linux distributions build libssh2 with the gcrypt library, some use openssl. Libssh2 has some issues when compiled with gcrypt, please use openssl.

&reference.ssh2.installation;
&reftitle.resources;

This extension defines the following resource types:

- SSH2 Session
- SSH2 Listener
- SSH2 SFTP
- SSH2 Publickey Subsystem (as of ssh2 0.10)