Juniper JunOS Network Automation

MCP Server

Field	Value
Repository	Juniper/junos-mcp-server
Transport	stdio (default for CLI), streamable-http (for IDE)
Python	3.10+ (3.11 recommended)
Protocol	SSH → NETCONF → PyEZ (junos-eznc)
Dependencies	junos-eznc>=2.7.4, jxmlease>=1.0.3, lxml>=6.0.0, mcp[cli]>=1.12.2, ncclient>=0.6.15, paramiko>=3.5.1
Install	git clone + pip install -r requirements.txt or pip install .
Entry Point	junos-mcp-server -f devices.json -t stdio or python3 jmcp.py -f devices.json -t stdio
Container	docker build -t junos-mcp-server . (python:3.11-slim based)

Device Inventory

Devices are defined in a devices.json file (not environment variables):

{
  "core-rtr-01": {
    "ip": "10.0.0.1",
    "port": 22,
    "username": "netops",
    "auth": {
      "type": "ssh_key",
      "private_key_path": "/home/user/.ssh/junos_key"
    }
  },
  "edge-rtr-02": {
    "ip": "10.0.0.2",
    "port": 22,
    "username": "admin",
    "auth": {
      "type": "password",
      "password": "changeme"
    }
  }
}

SSH key authentication is strongly recommended for production. Jumphost/ProxyCommand is supported via ssh_config field.

Environment Variables

Variable	Default	Purpose
JUNOS_DEVICES_FILE	devices.json	Path to device inventory JSON
JUNOS_TIMEOUT	360	Default command timeout in seconds

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Tools (10)

Device Inventory (3 tools)

Tool	Parameters	Description
get_router_list	—	List all available Junos routers (passwords/keys filtered from output)
add_device	device_name?, device_ip?, device_port?, username?, ssh_key_path?	Add a new Junos device interactively (streamable-http only)
reload_devices	file_name	Reload the device dictionary from a new JSON file

CLI Execution (2 tools)

Tool	Parameters	Description
execute_junos_command	router_name, command, timeout?	Execute a JunOS CLI command on a single router
execute_junos_command_batch	router_names, command, timeout?	Execute the same command on multiple routers in parallel

Configuration Management (3 tools)

Tool	Parameters	Description
get_junos_config	router_name	Retrieve the full running configuration (show configuration | display set)
junos_config_diff	router_name, version?	Compare current config against a rollback version (1-49)
load_and_commit_config	router_name, config_text, config_format?, commit_comment?	Load and commit configuration (formats: set, text, xml)

Template & Facts (2 tools)

Tool	Parameters	Description
render_and_apply_j2_template	template_content, vars_content, router_name?, router_names?, apply_config?, dry_run?, commit_comment?	Render Jinja2 template with YAML variables; optionally apply to one or many routers with dry-run support
gather_device_facts	router_name, timeout?	Gather device facts: hostname, model, serial, version, uptime, RE info

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Safety Features

Command Blocklist (block.cmd)

The server ships with a blocklist that prevents destructive CLI commands:

• request system reboot
• request system halt
• request system power-cycle
• request system power-off
• request system zeroize

Custom patterns (regex) can be added to block.cmd.

Configuration Blocklist (block.cfg)

Prevents dangerous configuration changes:

• set system root-authentication — blocks root password changes
• set system login user ... authentication — blocks user credential changes

Custom patterns (regex) can be added to block.cfg.

Credential Filtering

get_router_list automatically strips passwords and SSH key paths before returning device data.

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Workflows

1. JunOS Device Discovery

get_router_list → inventory all available Junos routers
→ gather_device_facts(router) per device → hostname, model, serial, version, uptime
→ Cross-reference with NetBox/Nautobot → flag discrepancies
→ GAIT

2. JunOS Health Check

get_router_list → identify target routers
→ execute_junos_command_batch(routers, "show chassis alarms") → alarm check
→ execute_junos_command_batch(routers, "show system processes extensive") → CPU/memory
→ execute_junos_command_batch(routers, "show interfaces terse") → interface status
→ execute_junos_command_batch(routers, "show bgp summary") → BGP peer health
→ Severity-sort findings → GAIT

3. JunOS Configuration Audit

get_router_list → select target routers
→ get_junos_config(router) → retrieve running config
→ junos_config_diff(router, version=1) → check for uncommitted or recent changes
→ Compare against golden config templates → flag deviations
→ GAIT

4. JunOS Configuration Deployment

ServiceNow CR must be in Implement state
→ get_junos_config(router) → baseline current config
→ render_and_apply_j2_template(template, vars, router, dry_run=true) → preview changes
→ render_and_apply_j2_template(template, vars, router, apply_config=true, commit_comment="CR-12345") → apply
→ get_junos_config(router) → verify post-change config
→ execute_junos_command(router, "show bgp summary") → verify protocol health
→ GAIT

5. JunOS Batch Operations

get_router_list → filter to target group (e.g., all edge routers)
→ execute_junos_command_batch(routers, "show version") → version inventory
→ execute_junos_command_batch(routers, "show ospf neighbor") → protocol health
→ Aggregate results → severity-sort → GAIT

6. JunOS Rollback Investigation

junos_config_diff(router, version=1) → compare against last committed config
→ junos_config_diff(router, version=2) → compare against version before that
→ Identify what changed, when, and the impact
→ execute_junos_command(router, "show system commit") → commit history
→ GAIT

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Integration with Other Skills

Skill	Integration
pyats-network	JunOS MCP for Juniper devices, pyATS MCP for Cisco devices — unified multi-vendor fleet management
netbox-reconcile	Cross-reference JunOS device facts (model, serial, version) against NetBox source of truth
nautobot-sot	Same as NetBox — validate Juniper device IPAM data in Nautobot
infrahub-sot	Cross-reference Infrahub node data with Juniper device inventory
itential-automation	Itential workflows can orchestrate JunOS config deployments; Junos command templates complement Itential's
servicenow-change-workflow	Gate all JunOS config commits behind ServiceNow Change Requests
gait-session-tracking	Every JunOS command, config push, and batch operation logged in GAIT
nso-device-ops	NSO for multi-vendor orchestration, JunOS MCP for direct Juniper device access
te-network-monitoring	Validate network health via ThousandEyes after JunOS config changes
fmc-firewall-ops	Correlate Juniper ACL/firewall-filter config with Cisco FMC security policies
subnet-calculator	VLSM planning for Juniper interface addressing
nvd-cve	Scan Junos OS versions against NVD vulnerability database

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JunOS MCP vs pyATS MCP

Capability	JunOS MCP	pyATS MCP
Vendor	Juniper only	Cisco (IOS-XE, NX-OS, IOS-XR)
Protocol	NETCONF via PyEZ	SSH + Genie parsers
CLI Execution	execute_junos_command	pyats_run_command
Batch Operations	execute_junos_command_batch (native parallel)	pyats_pcall (parallel pCall)
Config Retrieval	get_junos_config (set format)	pyats_run_command("show run")
Config Push	load_and_commit_config (NETCONF commit)	pyats_configure_device (SSH configure terminal)
Template Support	Built-in Jinja2 rendering + apply	External (Jinja2 → configure)
Config Diff	junos_config_diff (rollback compare)	Manual diff via show commands
Device Facts	gather_device_facts (PyEZ facts)	pyats_learn("platform")
Safety	block.cmd + block.cfg regex blocklists	Built-in destructive command blocking
MCP Tools	10	8

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Guardrails

• Always call get_router_list first — verify the target device exists before executing commands
• Always baseline before changes — call get_junos_config before any load_and_commit_config or template apply
• Use dry_run for templates — set dry_run=true on render_and_apply_j2_template to preview changes before committing
• Gate config changes — all load_and_commit_config and render_and_apply_j2_template(apply_config=true) calls must have a ServiceNow CR in Implement state
• Use batch for fleet ops — prefer execute_junos_command_batch over looping execute_junos_command for multi-router operations
• Set reasonable timeouts — default is 360s; reduce for simple show commands, increase for large config operations
• Include commit comments — always provide a commit_comment referencing the ServiceNow CR number
• Verify after config pushes — call get_junos_config and protocol-specific show commands after changes
• Respect the blocklists — block.cmd and block.cfg prevent destructive operations; do not bypass them
• Record in GAIT — every command, config push, batch operation, and template rendering must be logged