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.

import sys
import chilkat2

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 = chilkat2.Ssh()

port = 22
success = ssh.Connect("172.16.16.100",port)
if (success == False):
    print(ssh.LastErrorText)
    sys.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 == False):
    print(ssh.LastErrorText)
    sys.exit()

channelNum = ssh.QuickShell()
if (channelNum < 0):
    print(ssh.LastErrorText)
    sys.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 = True

# In unprivileged mode the switch prompt ends with ">".
success = ssh.ChannelReceiveUntilMatch(channelNum,">","utf-8",caseSensitive)
if (success == False):
    print(ssh.LastErrorText)
    sys.exit()

received = ssh.GetReceivedText(channelNum,"utf-8")
if (ssh.LastMethodSuccess == False):
    print(ssh.LastErrorText)
    sys.exit()

print(received)

# 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)
    sys.exit()

success = ssh.ChannelReceiveUntilMatch(channelNum,"Password:","utf-8",caseSensitive)
if (success == False):
    print(ssh.LastErrorText)
    sys.exit()

received = ssh.GetReceivedText(channelNum,"utf-8")
if (ssh.LastMethodSuccess == False):
    print(ssh.LastErrorText)
    sys.exit()

print(received)

# 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)
    sys.exit()

success = ssh.ChannelSendString(channelNum,"\r","utf-8")
if (success == False):
    print(ssh.LastErrorText)
    sys.exit()

# In privileged mode the prompt ends with "#" instead of ">".
success = ssh.ChannelReceiveUntilMatch(channelNum,"#","utf-8",caseSensitive)
if (success == False):
    print(ssh.LastErrorText)
    sys.exit()

received = ssh.GetReceivedText(channelNum,"utf-8")
if (ssh.LastMethodSuccess == False):
    print(ssh.LastErrorText)
    sys.exit()

print(received)

# 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)
    sys.exit()

# 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 = chilkat2.StringArray()
saMatch.Append("MySwitchName#")
saMatch.Append("--More--")

sbReceived = chilkat2.StringBuilder()
moreComing = True

while moreComing :
    success = ssh.ChannelReceiveUntilMatchN(channelNum,saMatch,"utf-8",caseSensitive)
    if (success == False):
        print(ssh.LastErrorText)
        sys.exit()

    sbReceived.Clear()
    pageText = ssh.GetReceivedText(channelNum,"utf-8")
    if (ssh.LastMethodSuccess == False):
        print(ssh.LastErrorText)
        sys.exit()

    sbReceived.Append(pageText)
    print(pageText)

    # 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)
            sys.exit()

ssh.Disconnect()