A PowerShell script to get the MAC address tables from Cisco routers/switches

Get-SwitchMACInfo.ps1

<#
.SYNOPSIS
This script gets MAC address tables from Cisco routers/switches running IOS using the SSH protocol.

.DESCRIPTION
There's a newer version of this here: https://github.com/supercheetah/winsysadmintools

The script uses the Plink (command line version of PuTTY, http://www.chiark.greenend.org.uk/~sgtatham/putty/download.html)
 to get the output of the command "show mac address-table" and put into a object array (i.e. table) that is outputted to
Out-GridView, and can optionally be saved to a CSV file.
#>
# author: Rene Horn, the.rhorn@gmail.com
# requirements:
#   at least PowerShell v3+
#   plink

<#
Copyright (c) 2015, Rene Horn
All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.

2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.

3. Neither the name of the copyright holder nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#>

param(
    [parameter(Mandatory=$false)]
    [alias("CN","Computer","Name","Switch","SwitchName")]
    [string[]]$ComputerName,
    [parameter(Mandatory=$false)]
    [alias("File","Path","List","SwitchListFile")]
    [string]$ComputerListFile,
    [parameter(Mandatory=$false)]
    [string]$SaveFile,
    [parameter(Mandatory=$false)]
    [switch]$NoGUI
)

[bool]$NoGUI = $NoGUI.IsPresent

if ($PSVersionTable.PSVersion.Major -lt 3) {
    Write-Error "PowerShell 3.0 or higher is required!"
    Exit -1
}

function Get-PlinkPath()
{
    if(!($plink_exe = Get-Command plink.exe -ErrorAction SilentlyContinue)) {
        Write-Error "Must have plink.exe in path!  Aborting..."
        Exit -1
    } else {
        return $plink_exe.Path
    }
}

function Construct-ObjectFromHeader([string]$computer,[string[]]$headers,[string[]]$split_line)
{
    [pscustomobject]$tbl_object = New-Object psobject -Property @{"hostname"=$computer}
    for($i=0; $i -lt $headers.Count; $i++) {
        $tbl_object | Add-Member -MemberType NoteProperty -Name $headers[$i] -Value $split_line[$i]
    }
    return $tbl_object
}

function Parse-Output([string]$computer, [string[]]$output_raw, [string[]]$cmds)
{
    $output_iter = 0
    for (; $output_iter -lt $output_raw.Count; $output_iter++) {
        if ($output_raw[$output_iter] -match "^\S+>.*") {
            break
        }
    }

    if (($output_iter+5) -ge $output_raw.Count) {
        Write-Error "No output from $computer, skipping..."
        return $null
    }

    $output_iter+=3 # skip the line for "term len 0" and the first command line output

    $cmds_results_hash = @{}
    foreach($cmd in $cmds) {
        # we don't care about the first two lines of the output...
        # this regex split allows us to capture headers like "Mac Address"
        # TODO: a more complex table parser would be needed for other tables, e.g. for "show interface status"
        $line_split_re = "\s{2}\s*"
        $headers = [regex]::Split($output_raw[$output_iter++].Trim(), $line_split_re)
        $output_tbl = @()
        do {
            $output_tbl += Construct-ObjectFromHeader $computer $headers ([regex]::Split($output_raw[$output_iter].Trim(), $line_split_re))
        } while (($output_raw[++$output_iter] -notmatch "^\S+>.*") -and ($output_iter -lt $output_raw.Count))
        $cmds_results_hash[$cmd] = $output_tbl
        $output_iter+=1 # skip blank line after command
        if ($output_iter -ge $output_raw.Count) {
            Write-Error "Truncated output!"
            break
        }
    }
    return $cmds_results_hash
}

function Ask-ForHostKeyAccept([string]$host_key_err_msg)
{
    $split_string = $host_key_err_msg.Trim().Split("`n")
    $caption = "Accept host key?"
    $message = (@"
{0}
If you trust this host, click Yes to add the key to
PuTTY's cache and carry on connecting.
If you want to carry on connecting just once, without
adding the key to the cache, click No.
If you do not trust this host, click Cancel to abandon the
connection.
Store key in cache?
"@ -f [string]::Join("`n", $split_string[0..($split_string.Count - 2)]))

    $response = [System.Windows.Forms.MessageBox]::Show($message, $caption, "YesNoCancel", "Warning", "Button1", 0)
    if ($response -eq "Yes") {
        return 'y'
    } elseif ($response -eq "No") {
        return 'n'
    } else {
        return "`n"
    }
}

function New-PlinkSession([string]$computer, [string[]]$cisco_ios_cmds, [pscredential]$credentials, [string]$host_key_err_msg = $null)
{
    # returns: System.Diagnostics.Process for plink, StreamReader for its stdin, stdout, and async read variables for stdout and stderr, respectively
    # if this returns null, that means the host key was rejected
    $plink_exe = Get-PlinkPath

    # The process start info needs to be set up separately.
    # Creating a new System.Diagnostics.Process object, and setting up its StartInfo, and then starting it doesn't seem to work.
    # Also, calling plink directly here does not work properly, nor does using Start-Process.  The output always gets truncated if there's too much.
    # The reason seems to be that .NET has a buffer limit (http://www.codeducky.org/process-handling-net/) for stdin, stdout, and stderr, so they
    # need to be written to/read from asynchronously so that those streams will have some other buffer to use that don't have those limitations.
    $plink_proc_info = New-Object System.Diagnostics.ProcessStartInfo
    $plink_proc_info.FileName = $plink_exe
    $plink_proc_info.UseShellExecute = $false
    $plink_proc_info.RedirectStandardError = $true
    $plink_proc_info.RedirectStandardInput = $true
    $plink_proc_info.RedirectStandardOutput = $true
    $plink_proc_info.CreateNoWindow = $true
    # putting the arguments here to minimize the amount of time the password shows up in clear text in memory
    $plink_proc_info.Arguments = ('-pw {0} {1}@{2}' -f $credentials.GetNetworkCredential().Password, $credentials.GetNetworkCredential().UserName, $computer)
    $plink_proc = $null
    $host_key_accepted = $null
    if (([string]::IsNullOrEmpty($host_key_err_msg))) {
        $plink_proc_info.Arguments = '-batch ' + $plink_proc_info.Arguments
    } else {
        $host_key_accepted = (Ask-ForHostKeyAccept $host_key_err_msg)
        if ($host_key_accepted -eq "`n") {
            Write-Warning "Host key not accepted, skipping $computer..."
            return $null
        }
    }

    $plink_proc = [System.Diagnostics.Process]::Start($plink_proc_info)
    $plink_proc_info.Arguments = "" # for security reasons, blanking this out so there aren't so many copies of the password in clear text floating around in memory

    if (!([string]::IsNullOrEmpty($host_key_err_msg))) {
        $plink_proc.StandardInput.WriteLine("$host_key_accepted")
        # plink seems to need need a break after prompting for the host key
        # seems to randomly fail at just a one or two seconds pause, three seems safe
        Start-Sleep 3
    }
    
    return $plink_proc, [System.IO.StreamWriter]($plink_proc.StandardInput), $plink_proc.StandardOutput.ReadToEndAsync(), $plink_proc.StandardInput, $plink_proc.StandardError.ReadToEndAsync()
}

function Test-HostKeyIsCached([string]$plink_stderr_result)
{
    $err_split = $plink_stderr_result.Trim().Split("`n")
    return ($err_split[($err_split.Count - 1)].Trim() -notmatch "Connection abandoned.")
}

function Invoke-CiscoIOSCmds([string]$computer, [string[]]$cisco_ios_cmds, [pscredential]$credentials)
{
    $host_key_results_err = $null
    do {
        # PowerShell seems to lock stdin and stdout until the process exits, so we can't do anything with them until it exits.
        $plink_proc, $plink_stdin, $plink_stdout, $plink_stderr = New-PlinkSession $computer $cisco_ios_cmds $credentials $host_key_results_err
        if ($plink_proc -eq $null) {
            return $null
        }

        # We don't want to use WriteLine() here because it writes \n\r to the stream, which gets interpreted as two EOLs by Cisco IOS
        $plink_stdin.Write("terminal length 0`n")
        # Cisco IOS gets a little weird if it doesn't get a break between commands, so we sleep for a bit.
        Start-Sleep 1
        foreach ($cmd in $cisco_ios_cmds) {
            $plink_stdin.Write("$cmd`n")
            Start-Sleep 1
        }

        $plink_stdin.Write("exit`n")
        $plink_proc.WaitForExit()
        $cmds_response = $plink_stdout.Result
    
        if ($plink_proc.ExitCode -ne 0) {
            $plink_err_file = "$pwd\$computer.error.log"
            $plink_stderr.Result | Out-File $plink_err_file
            Write-Error "Connection to $computer failed, check $plink_err_file."
            return $null
        } elseif (!(Test-HostKeyIsCached $plink_stderr.Result)) {
            $host_key_results_err = $plink_stderr.Result
        } else {
            $host_key_results_err = $null
        }
    } while ($host_key_results_err -ne $null)
    $cmds_output = Parse-Output $computer $cmds_response.Split("`n") $cisco_ios_cmds
    return $cmds_output
}

function Get-AddressTables([string[]]$computer_list) {
    begin {
        $credentials = (Get-Credential)
        if ($credentials -eq $null) {
            Write-Error "Logon cancelled, abandon all hope..."
            Exit -15
        }
        $cisco_ios_cmd = "sh mac address-table | e -|CPU|Mac Address Table|Total"
    }
    process {
        $address_table = @()
        $i = 1
        foreach ($computer in $computer_list) {
            Write-Progress -Activity "Getting MAC address table..." -Status $computer -PercentComplete ($i++/$computer_list.Count*100.00)
            $buffer = Invoke-CiscoIOSCmds $computer.Trim() $cisco_ios_cmd $credentials
            if ($buffer -ne $null) {
                $address_table += $buffer[$cisco_ios_cmd]
            }
        }
        return $address_table
    }
    end {}
}

function Open-ComputerListFile()
{
    [System.Reflection.Assembly]::LoadWithPartialName("System.windows.forms") | Out-Null

    $open_file_dlg = New-Object System.Windows.Forms.OpenFileDialog
    $open_file_dlg.Filter = "All files (*.*)| *.*"
    $open_file_dlg.ShowDialog() | Out-Null
    $open_file_dlg.FileName
}

function Save-ReportFile()
{
    [System.Reflection.Assembly]::LoadWithPartialName("System.windows.forms") | Out-Null

    $save_file_dlg = New-Object System.Windows.Forms.SaveFileDialog
    $save_file_dlg.Filter = "CSV file (*.csv) | *.csv"
    $save_file_dlg.OverwritePrompt = $true
    $save_file_dlg.ShowDialog() | Out-Null
    $save_file_dlg.FileName
}

function Show-GUI()
{
    [System.Reflection.Assembly]::LoadWithPartialName("System.Drawing") | Out-Null
    [System.Reflection.Assembly]::LoadWithPartialName("System.Windows.Forms") | Out-Null

    # creating it here so we can get the default height of a single line text box for reference
    $computer_list_textbox = New-Object System.Windows.Forms.TextBox
    $textbox_height = $computer_list_textbox.Height

    $main_dlg_box = New-Object System.Windows.Forms.Form -Property @{
        ClientSize = New-Object System.Drawing.Size(600,($textbox_height*16))
        MaximizeBox = $false
        MinimizeBox = $false
        FormBorderStyle = 'FixedSingle'
        Text = "Get MAC address tables"
    }

    # widget size and location variables
    $ctrl_width_col = $main_dlg_box.ClientSize.Width/15
    $ctrl_height_row = $textbox_height
    $max_ctrl_width = $main_dlg_box.ClientSize.Width - $ctrl_width_col*2
    $max_ctrl_height = $main_dlg_box.ClientSize.Height - $ctrl_height_row*2
    $right_edge_x = $max_ctrl_width
    $left_edge_x = $ctrl_width_col
    $bottom_edge_y = $max_ctrl_height
    $top_edge_y = $ctrl_height_row

    $computer_list_label = New-Object System.Windows.Forms.Label -Property @{
        Size = New-Object System.Drawing.Size($max_ctrl_width, $textbox_height)
        Text = "Enter Cisco switch/router hostnames/IP addresses (comma separated or each on their own line):"
        Location = New-Object System.Drawing.Point($left_edge_x, $top_edge_y)
    }
    $main_dlg_box.Controls.Add($computer_list_label)

    $computer_list_textbox.Multiline = $true
    $computer_list_textbox.Height = $textbox_height*6
    $computer_list_textbox.Width = $max_ctrl_width
    $computer_list_textbox.Location = New-Object System.Drawing.Point($left_edge_x, ($top_edge_y + $ctrl_height_row))
    $main_dlg_box.Controls.Add($computer_list_textbox)

    $open_listfile_button = New-Object System.Windows.Forms.Button -Property @{
        Size = New-Object System.Drawing.Size(($ctrl_width_col*4), $textbox_height)
        Location = New-Object System.Drawing.Point($left_edge_x, ($computer_list_textbox.Height + $computer_list_textbox.Location.Y + $ctrl_height_row))
        Text = "&Open file with hostnames"
    }
    $open_listfile_button.Add_Click({$main_dlg_box.Enabled=$false; $open_listfile_textbox.Text=Open-ComputerListFile; $main_dlg_box.Enabled=$true})
    $main_dlg_box.Controls.Add($open_listfile_button)

    $open_listfile_textbox = New-Object System.Windows.Forms.TextBox -Property @{
        Size = New-Object System.Drawing.Size(($max_ctrl_width - $open_listfile_button.Width - $ctrl_width_col*2), $textbox_height)
        ReadOnly = $true
        BackColor = $main_dlg_box.BackColor
        TabStop = $false
    }
    $open_listfile_textbox.Location = New-Object System.Drawing.Point(($right_edge_x - $open_listfile_textbox.Width), $open_listfile_button.Location.Y)
    $main_dlg_box.Controls.Add($open_listfile_textbox)

    $save_file_button = New-Object System.Windows.Forms.Button -Property @{
        Size = New-Object System.Drawing.Size($open_listfile_button.Width, $textbox_height)
        Location = New-Object System.Drawing.Point($left_edge_x, ($open_listfile_button.Height + $open_listfile_button.Location.Y + $ctrl_height_row))
        Text = "&Save report to..."
    }
    $save_file_button.Add_Click({$main_dlg_box.Enabled=$false; $save_file_textbox.Text=Save-ReportFile; $main_dlg_box.Enabled=$true})
    $main_dlg_box.Controls.Add($save_file_button)

    $save_file_textbox = New-Object System.Windows.Forms.TextBox -Property @{
        Size = New-Object System.Drawing.Size(($max_ctrl_width - $save_file_button.Width - $ctrl_width_col*2), $textbox_height)
        ReadOnly = $true
        BackColor = $main_dlg_box.BackColor
        TabStop = $false
    }
    $save_file_textbox.Location = New-Object System.Drawing.Point(($right_edge_x - $save_file_textbox.Width), $save_file_button.Location.Y)
    $main_dlg_box.Controls.Add($save_file_textbox)

    $ok_button = New-Object System.Windows.Forms.Button -Property @{
        Size = New-Object System.Drawing.Size(($ctrl_width_col*2), $textbox_height)
        DialogResult = "OK"
        Text = "O&k"
    }
    $ok_button.Location = New-Object System.Drawing.Point(($right_edge_x - $ok_button.Width), ($bottom_edge_y - $ok_button.Height))
    $main_dlg_box.Controls.Add($ok_button)

    $cancel_button = New-Object System.Windows.Forms.Button -Property @{
        Size = New-Object System.Drawing.Size(($ctrl_width_col*2), $textbox_height)
        DialogResult = "Cancel"
        Text = "&Cancel"
    }
    $cancel_button.Location = New-Object System.Drawing.Point($left_edge_x, $ok_button.Location.Y)
    $main_dlg_box.Controls.Add($cancel_button)

    if($main_dlg_box.ShowDialog() -eq "Cancel") {
        return $null
    } else {
        return ([regex]::Split($computer_list_textbox.Text.Trim(), ",|`n")), $open_listfile_textbox.Text, $save_file_textbox.Text
    }
}

$computer_list = $null
while([string]::IsNullOrEmpty($computer_list)) {
    if (![string]::IsNullOrEmpty($ComputerName)) {
        $computer_list = @($ComputerName)
    } elseif (![string]::IsNullOrEmpty($ComputerListFile)) {
        $computer_list = (Get-Content -Path $ComputerListFile)
    } elseif($NoGUI) {
        $buffer = Read-Host "Please specify a switch/rouer hostname(s) (comma separated) or file containing the hostnames"
        if (Test-Path $buffer -ErrorAction SilentlyContinue) {
            $ComputerListFile = $buffer
        } elseif ($buffer -match "(\w+,?)+") { # if it's not a valid file path, assume we were given a hostname(s)
            $ComputerName = $buffer.Split(",")
        } else {
            Write-Error "I don't understand!"
        }
    } else {
        $buffer = Show-GUI
        if ($buffer -ne $null) {
            $ComputerName, $ComputerListFile, $SaveFile = $buffer
        } else {
            Exit 0
        }
    }
}
$address_tables = Get-AddressTables $computer_list

if (![string]::IsNullOrEmpty($SaveFile)) {
    $address_tables | Export-Csv -Path $SaveFile -NoTypeInformation
}

$address_tables | ogv -Wait -Title "MAC address tables"

Are you able to run this script specifying the hostname .csv and the output report name in the options of running the script or would it have to be manually edited within the script itself to make that happen?

Are you able to run this script specifying the hostname .csv and the output report name in the options of running the script or would it have to be manually edited within the script itself to make that happen?

Yeah, when you call this script to run it, you will want to specify the switches' names (comma separated) and save file like this:

/path/to/Get-SwitchMACInfo.ps1 -Switch myswitch01,myswitch02,myswitch03 -SaveFile switchreport.csv

Also, there's a newer version of this here: https://github.com/supercheetah/winsysadmintools

Hi. I keep getting the following error when I run the script:

Parse-Output : No output from 192.168.10.1, skipping...
At \server\users\name\PowerShell\Get-SwitchMACInfo.ps1:210 char:20

• ... ds_output = Parse-Output $computer $cmds_response.Split("`n") $cisco_ ...

•             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  

  • CategoryInfo : NotSpecified: (:) [Write-Error], WriteErrorException
  • FullyQualifiedErrorId : Microsoft.PowerShell.Commands.WriteErrorException,Pa
    rse-Output

I have been running it by entering the IP of the switch in the GUI.

Any idea what might be the problem?

Thanks.

This script is exactly what I've been looking for! Unfortunately, we don't use Cisco switches, but the "sh mac address-table" is identical for our switch OS'. I do however need to precede the "show" command with an "enable" command.

I have to admit I'm a Powershell syntax novice, and I could use a little help updating the script to send the enable command before the "show" command.

Can anyone help?