# Switch plugin: the switch is the muscle, Forescout is the brain

Source: https://ai.techclick.in/blog_forescout_switch_plugin_vlan_acl
Markdown: https://ai.techclick.in/blog_forescout_switch_plugin_vlan_acl.md
Publisher: Techclick Infosec Pvt Ltd

Switch plugin uses CLI/SNMP to move VLAN or ACL. Dummy sw-access-01. Not Virtual FW.

## The ticket

 A control policy “quarantine VLAN 99” ran campus-wide. Phones lost CDP voice VLAN. Helpdesk spent the night. The plugin worked. The blast radius was the bug.

  Quick interview answer

 Switch plugin: Forescout uses SNMP/CLI/NETCONF (train-dependent) to apply VLAN/ACL. The NAD is still the enforcer. Scope the switch list, use a dedicated TACACS user, and test one interface. Voice: do not strip the voice VLAN. Rollback = known good template.

  Hero · CLI muscle

 If you can do it in IOS, the plugin can do it at 02:00 — for better or worse.
  Lab data · dummy only
 Enterprise Manager  fs-em   10.10.10.30  · Appliance  fs-app1   10.10.10.31  · span/mirror on  sw-access-01  · same LAN  10.20.30.0/24  · Priya  10.20.30.80  · printer  10.20.30.60  · OT PLC  10.50.1.10 . Not a live customer.

## Plugin vs Virtual FW

     Switch plugin  Virtual FW

  Where enforced  Switch  Appliance path
  Sees original MAC/VLAN  Yes  May rewrite path
  Blast radius  Whole switch if scoped wrong  Hosts the appliance can reach

     https://fs-em.techclick-lab.in

     Training mock · not live

       Forescout Console

       Asset Inventory  Policy  Channels  Tools

       Tools → Options → Switch / Plugin

### sw-access-01

        IP  10.10.10.2

  Access  SSH, user fs-nac (TACACS)

  Allowed commands  vlan / interface switchport access

  Pilot ports  Gi1/0/20 only

        Cancel  Save

   Switch plugin inventory. Training mock.

## When to use it

 You already own Catalyst access and want VLAN quarantine without ISE. If ISE already owns 802.1X, do  not  also plugin-VLAN those ports.

## How you enable it

- #### Side A — AAA user fs-nac can only change a port range. Logged.

- #### Side B — plugin + one port Map Gi1/0/20 camera to VLAN 50. Not the whole stack.

- #### Side C — prove + rollback show run interface Gi1/0/20 . Keep the old VLAN in the ticket. Revert command ready.

  dummy proof  show run interface Gi1/0/20
# switchport access vlan 50
# switchport voice vlan 70   ← must still be here for phones
show authentication sessions interface Gi1/0/20

## Four plugin failures

### 1 · Credentials = local cisco/cisco

### 2 · Policy applies to all interfaces including uplinks

### 3 · Voice VLAN stripped

### 4 · No rollback user on-call

## How to prove it

  Close the ticket only when

 1) Only the test port changed. 2) Voice VLAN intact if it is a phone. 3) AAA log shows fs-nac. 4) Rollback pasted in the ticket.

## Traps

   Wrong  Right

  Plugin + ISE VLAN on same port  One owner (lesson 6)
  Wildcard interface Gi1/0/*  Explicit list

## Knowledge check

   Judgment items. One best answer. Reasons send you back to the matching section.

       Q1
       Switch plugin enforces on…

           The switch via CLI/SNMP
           Only the EM CPU
           AD
           MnT

       Correct:  a . Concept.

       Q2
       Biggest blast-radius mistake?

           Applying to uplinks / all ports
           Testing one access port
           Using TACACS
           Keeping voice VLAN

       Correct:  a . Failure 2.

       Q3
       Phone port after VLAN move must still have…

           Voice VLAN
           No spanning-tree
           No CDP
           OSPF

       Correct:  a . Failure 3.

       Q4
       Plugin vs Virtual FW?

           Plugin = switch is muscle; Virtual FW = appliance path
           Identical
           Plugin is PEAP
           Virtual FW is SPAN

       Correct:  a . Table.

       Q5
       If ISE already does 802.1X on that port…

           Do not also plugin-VLAN it
           Always add plugin
           Disable ISE
           Disable SPAN

       Correct:  a . Choose.

       Q6
       Least privilege user?

           fs-nac with interface commands only
           local admin everywhere
           No logging
           Shared enable secret in Slack

       Correct:  a . Runbook A.

       Check answers
       Reset

  Forescout class series:   Three products  ·  First day  ·  Discovery  ·  Classification  ·  Policy  ·  Enforcement  ·  Switch plugin  ·  eyeExtend  ·  OT / IoT  ·  vs ISE + interview

## Sources

- Forescout switch plugin / switch integration guides for your IOS train.
- Lesson 6 — one enforcement owner.

 Related:  Forescout evidence desk  ·  session factory  ·  Cisco ISE series .

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