SSH to a Cisco Switch - Processing "More" Responses

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Demonstrates connecting to a Cisco switch, entering privileged mode with the ena command, and running a command whose response is paged. Each page ends with --More-- and requires a SPACE character to request the next page.

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.

require 'chilkat'

success = false

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

#  Demonstrates connecting to a Cisco switch, entering privileged mode, and running a command
#  whose response is paged -- each page ends with "--More--" and requires a SPACE character to
#  request the next page.

ssh = Chilkat::CkSsh.new()

port = 22
success = ssh.Connect("172.16.16.100",port)
if (success == false)
    print ssh.lastErrorText() + "\n";
    exit
end

#  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 == false)
    print ssh.lastErrorText() + "\n";
    exit
end

channelNum = ssh.QuickShell()
if (channelNum < 0)
    print ssh.lastErrorText() + "\n";
    exit
end

#  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.put_ReadTimeoutMs(15000)

caseSensitive = true

#  In unprivileged mode the switch prompt ends with ">".
success = ssh.ChannelReceiveUntilMatch(channelNum,">","utf-8",caseSensitive)
if (success == false)
    print ssh.lastErrorText() + "\n";
    exit
end

received = ssh.getReceivedText(channelNum,"utf-8")
if (ssh.get_LastMethodSuccess() == false)
    print ssh.lastErrorText() + "\n";
    exit
end

print received + "\n";

#  Send "ena" to enter privileged mode.  Cisco devices expect a bare CR to terminate a command.
success = ssh.ChannelSendString(channelNum,"ena\r","utf-8")
if (success == false)
    print ssh.lastErrorText() + "\n";
    exit
end

success = ssh.ChannelReceiveUntilMatch(channelNum,"Password:","utf-8",caseSensitive)
if (success == false)
    print ssh.lastErrorText() + "\n";
    exit
end

received = ssh.getReceivedText(channelNum,"utf-8")
if (ssh.get_LastMethodSuccess() == false)
    print ssh.lastErrorText() + "\n";
    exit
end

print received + "\n";

#  The enable password is separate from the login password, and likewise should come from a
#  secure source rather than being hard-coded.
enablePassword = "myEnablePassword"
success = ssh.ChannelSendString(channelNum,enablePassword,"utf-8")
if (success == false)
    print ssh.lastErrorText() + "\n";
    exit
end

success = ssh.ChannelSendString(channelNum,"\r","utf-8")
if (success == false)
    print ssh.lastErrorText() + "\n";
    exit
end

#  In privileged mode the prompt ends with "#" instead of ">".
success = ssh.ChannelReceiveUntilMatch(channelNum,"#","utf-8",caseSensitive)
if (success == false)
    print ssh.lastErrorText() + "\n";
    exit
end

received = ssh.getReceivedText(channelNum,"utf-8")
if (ssh.get_LastMethodSuccess() == false)
    print ssh.lastErrorText() + "\n";
    exit
end

print received + "\n";

#  Run a command whose output is delivered a page at a time.
success = ssh.ChannelSendString(channelNum,"show running-config\r","utf-8")
if (success == false)
    print ssh.lastErrorText() + "\n";
    exit
end

#  Each read ends either at the device prompt (output complete) or at "--More--" (another page
#  is waiting).  Match the full prompt rather than a bare "#", because "#" also appears inside
#  configuration text and would match too early.
saMatch = Chilkat::CkStringArray.new()
saMatch.Append("MySwitchName#")
saMatch.Append("--More--")

sbReceived = Chilkat::CkStringBuilder.new()
moreComing = true

while moreComing
    success = ssh.ChannelReceiveUntilMatchN(channelNum,saMatch,"utf-8",caseSensitive)
    if (success == false)
        print ssh.lastErrorText() + "\n";
        exit
    end

    sbReceived.Clear()
    pageText = ssh.getReceivedText(channelNum,"utf-8")
    if (ssh.get_LastMethodSuccess() == false)
        print ssh.lastErrorText() + "\n";
        exit
    end

    sbReceived.Append(pageText)
    print pageText + "\n";

    #  If this page ended with "--More--", send a SPACE to request the next page.
    moreComing = sbReceived.Contains("--More--",caseSensitive)
    if (moreComing)
        success = ssh.ChannelSendString(channelNum," ","utf-8")
        if (success == false)
            print ssh.lastErrorText() + "\n";
            exit
        end

    end

end

ssh.Disconnect()