PHP ActiveX

SSH Commands to a Cisco Switch

Demonstrates establishing an SSH session with a Cisco switch (or similar device) and sending commands in a device console session. Each command is sent, and its output is read up to the device's next prompt.

Note: QuickShell allocates a PTY, which is what a network device console expects. The device presents an interactive prompt, and each command's output is read up to the next prompt.

Background: Network devices differ from general-purpose servers in that they expose a menu- or prompt-driven console rather than a Unix shell, so exec requests are usually unavailable and driving the interactive console is the only option. That makes prompt matching the synchronization mechanism, and it is why a PTY is appropriate here despite the general advice to avoid one. Retrieving the received text between commands is essential: a prompt left in the buffer would make the next receive return immediately with the wrong output.

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<?php

$success = 0;

//  This example requires the Chilkat API to have been previously unlocked.
//  See Global Unlock Sample for sample code.

//  Demonstrates establishing an SSH session with a Cisco switch (or similar device) and sending
//  commands in a device console session.
//  
//  Note: QuickShell allocates a PTY, which is what a network device console expects.  The device
//  presents an interactive prompt, and each command's output is read up to the next prompt.

$ssh = new COM("Chilkat.Ssh");

$port = 22;
$success = $ssh->Connect('172.16.16.100',$port);
if ($success == 0) {
    print $ssh->LastErrorText . "\n";
    exit;
}

//  Normally you would not hard-code the password in source.  You should instead obtain it
//  from an interactive prompt, environment variable, or a secrets vault.
$password = 'mySshPassword';

$success = $ssh->AuthenticatePw('mySshLogin',$password);
if ($success == 0) {
    print $ssh->LastErrorText . "\n";
    exit;
}

//  Start a shell session.
$channelNum = $ssh->QuickShell();
if ($channelNum < 0) {
    print $ssh->LastErrorText . "\n";
    exit;
}

//  IMPORTANT: Set a read timeout before receiving until a match.  ReadTimeoutMs defaults to 0,
//  which means no limit -- without it, this call waits forever if the received data never
//  contains a match.
$ssh->ReadTimeoutMs = 15000;

$caseSensitive = 1;

//  The switch presents a prompt ending in "#".  Reading up to it confirms the session is ready.
$success = $ssh->ChannelReceiveUntilMatch($channelNum,'#','utf-8',$caseSensitive);
if ($success == 0) {
    print $ssh->LastErrorText . "\n";
    exit;
}

$cmdOutput = $ssh->getReceivedText($channelNum,'utf-8');
if ($ssh->LastMethodSuccess == 0) {
    print $ssh->LastErrorText . "\n";
    exit;
}

print $cmdOutput . "\n";

//  Send a command and read its output up to the next prompt.
$success = $ssh->ChannelSendString($channelNum,'show clock\n','utf-8');
if ($success == 0) {
    print $ssh->LastErrorText . "\n";
    exit;
}

$success = $ssh->ChannelReceiveUntilMatch($channelNum,'#','utf-8',$caseSensitive);
if ($success == 0) {
    print $ssh->LastErrorText . "\n";
    exit;
}

//  Retrieving the text also clears the receive buffer, which matters: if the prompt were left
//  buffered, the next receive would match it immediately and return the wrong output.
$cmdOutput = $ssh->getReceivedText($channelNum,'utf-8');
if ($ssh->LastMethodSuccess == 0) {
    print $ssh->LastErrorText . "\n";
    exit;
}

print $cmdOutput . "\n";

//  Additional commands follow the same send / read-to-prompt / retrieve pattern.
$success = $ssh->ChannelSendString($channelNum,'show version\n','utf-8');
if ($success == 0) {
    print $ssh->LastErrorText . "\n";
    exit;
}

$success = $ssh->ChannelReceiveUntilMatch($channelNum,'#','utf-8',$caseSensitive);
if ($success == 0) {
    print $ssh->LastErrorText . "\n";
    exit;
}

$cmdOutput = $ssh->getReceivedText($channelNum,'utf-8');
if ($ssh->LastMethodSuccess == 0) {
    print $ssh->LastErrorText . "\n";
    exit;
}

print $cmdOutput . "\n";

$ssh->Disconnect();

?>