DHCP Leases
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Next-Generation Firewall Docs
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PAN-OS 11.1 & Later
- PAN-OS 11.1 & Later
- PAN-OS 11.0 (EoL)
- PAN-OS 10.2
- PAN-OS 10.1
- PAN-OS 10.0 (EoL)
- PAN-OS 9.1 (EoL)
- Cloud Management of NGFWs
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- Management Interfaces
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- Launch the Web Interface
- Use the Administrator Login Activity Indicators to Detect Account Misuse
- Manage and Monitor Administrative Tasks
- Commit, Validate, and Preview Firewall Configuration Changes
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- Export Configuration Table Data
- Use Global Find to Search the Firewall or Panorama Management Server
- Manage Locks for Restricting Configuration Changes
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- Define Access to the Web Interface Tabs
- Provide Granular Access to the Monitor Tab
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- Provide Granular Access to the Objects Tab
- Provide Granular Access to the Network Tab
- Provide Granular Access to the Device Tab
- Define User Privacy Settings in the Admin Role Profile
- Restrict Administrator Access to Commit and Validate Functions
- Provide Granular Access to Global Settings
- Provide Granular Access to the Panorama Tab
- Provide Granular Access to Operations Settings
- Panorama Web Interface Access Privileges
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- Reset the Firewall to Factory Default Settings
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- Plan Your Authentication Deployment
- Pre-Logon for SAML Authentication
- Configure SAML Authentication
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- Test Authentication Server Connectivity
- Troubleshoot Authentication Issues
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- Keys and Certificates
- Default Trusted Certificate Authorities (CAs)
- Certificate Deployment
- Configure the Master Key
- Export a Certificate and Private Key
- Configure a Certificate Profile
- Configure an SSL/TLS Service Profile
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- Replace the Certificate for Inbound Management Traffic
- Configure the Key Size for SSL Forward Proxy Server Certificates
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- HA Overview
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- Prerequisites for Active/Active HA
- Configure Active/Active HA
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- Use Case: Configure Active/Active HA with Route-Based Redundancy
- Use Case: Configure Active/Active HA with Floating IP Addresses
- Use Case: Configure Active/Active HA with ARP Load-Sharing
- Use Case: Configure Active/Active HA with Floating IP Address Bound to Active-Primary Firewall
- Use Case: Configure Active/Active HA with Source DIPP NAT Using Floating IP Addresses
- Use Case: Configure Separate Source NAT IP Address Pools for Active/Active HA Firewalls
- Use Case: Configure Active/Active HA for ARP Load-Sharing with Destination NAT
- Use Case: Configure Active/Active HA for ARP Load-Sharing with Destination NAT in Layer 3
- HA Clustering Overview
- HA Clustering Best Practices and Provisioning
- Configure HA Clustering
- Refresh HA1 SSH Keys and Configure Key Options
- HA Firewall States
- Reference: HA Synchronization
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- Use the Dashboard
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- Monitor Block List
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- Report Types
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- Configure Syslog Monitoring
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- Traffic Log Fields
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- Monitor Transceivers
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- User-ID Overview
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- App-ID Overview
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- Applications with Implicit Support
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- Prepare to Deploy App-ID Cloud Engine
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- App-ID Cloud Engine Processing and Policy Usage
- New App Viewer (Policy Optimizer)
- Add Apps to an Application Filter with Policy Optimizer
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- Replace an RMA Firewall (ACE)
- Impact of License Expiration or Disabling ACE
- Commit Failure Due to Cloud Content Rollback
- Troubleshoot App-ID Cloud Engine
- Application Level Gateways
- Disable the SIP Application-level Gateway (ALG)
- Maintain Custom Timeouts for Data Center Applications
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- Decryption Overview
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- Keys and Certificates for Decryption Policies
- SSL Forward Proxy
- SSL Forward Proxy Decryption Profile
- SSL Inbound Inspection
- SSL Inbound Inspection Decryption Profile
- SSL Protocol Settings Decryption Profile
- SSH Proxy
- SSH Proxy Decryption Profile
- Profile for No Decryption
- SSL Decryption for Elliptical Curve Cryptography (ECC) Certificates
- Perfect Forward Secrecy (PFS) Support for SSL Decryption
- SSL Decryption and Subject Alternative Names (SANs)
- TLSv1.3 Decryption
- High Availability Not Supported for Decrypted Sessions
- Decryption Mirroring
- Configure SSL Forward Proxy
- Configure SSL Inbound Inspection
- Configure SSH Proxy
- Configure Server Certificate Verification for Undecrypted Traffic
- Post-Quantum Cryptography Detection and Control
- Enable Users to Opt Out of SSL Decryption
- Temporarily Disable SSL Decryption
- Configure Decryption Port Mirroring
- Verify Decryption
- Activate Free Licenses for Decryption Features
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- Policy Types
- Policy Objects
- Track Rules Within a Rulebase
- Enforce Policy Rule Description, Tag, and Audit Comment
- Move or Clone a Policy Rule or Object to a Different Virtual System
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- External Dynamic List
- Built-in External Dynamic Lists
- Configure the Firewall to Access an External Dynamic List
- Retrieve an External Dynamic List from the Web Server
- View External Dynamic List Entries
- Exclude Entries from an External Dynamic List
- Enforce Policy on an External Dynamic List
- Find External Dynamic Lists That Failed Authentication
- Disable Authentication for an External Dynamic List
- Register IP Addresses and Tags Dynamically
- Use Dynamic User Groups in Policy
- Use Auto-Tagging to Automate Security Actions
- CLI Commands for Dynamic IP Addresses and Tags
- Application Override Policy
- Test Policy Rules
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- Network Segmentation Using Zones
- How Do Zones Protect the Network?
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PAN-OS 11.1 & Later
- PAN-OS 11.1 & Later
- PAN-OS 11.0 (EoL)
- PAN-OS 10.2
- PAN-OS 10.1
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- Tap Interfaces
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- Layer 2 and Layer 3 Packets over a Virtual Wire
- Port Speeds of Virtual Wire Interfaces
- LLDP over a Virtual Wire
- Aggregated Interfaces for a Virtual Wire
- Virtual Wire Support of High Availability
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- VLAN-Tagged Traffic
- Virtual Wire Subinterfaces
- Configure Virtual Wires
- Configure a PPPoE Client on a Subinterface
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- Configure an Aggregate Interface Group
- Configure Bonjour Reflector for Network Segmentation
- Use Interface Management Profiles to Restrict Access
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- DHCP Overview
- Firewall as a DHCP Server and Client
- Firewall as a DHCPv6 Client
- DHCP Messages
- Dynamic IPv6 Addressing on the Management Interface
- Configure an Interface as a DHCP Server
- Configure an Interface as a DHCPv4 Client
- Configure an Interface as a DHCPv6 Client with Prefix Delegation
- Configure the Management Interface as a DHCP Client
- Configure the Management Interface for Dynamic IPv6 Address Assignment
- Configure an Interface as a DHCP Relay Agent
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- DNS Overview
- DNS Proxy Object
- DNS Server Profile
- Multi-Tenant DNS Deployments
- Configure a DNS Proxy Object
- Configure a DNS Server Profile
- Use Case 1: Firewall Requires DNS Resolution
- Use Case 2: ISP Tenant Uses DNS Proxy to Handle DNS Resolution for Security Policies, Reporting, and Services within its Virtual System
- Use Case 3: Firewall Acts as DNS Proxy Between Client and Server
- DNS Proxy Rule and FQDN Matching
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- NAT Rule Capacities
- Dynamic IP and Port NAT Oversubscription
- Dataplane NAT Memory Statistics
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- Translate Internal Client IP Addresses to Your Public IP Address (Source DIPP NAT)
- Create a Source NAT Rule with Persistent DIPP
- PAN-OS
- Strata Cloud Manager
- Enable Clients on the Internal Network to Access your Public Servers (Destination U-Turn NAT)
- Enable Bi-Directional Address Translation for Your Public-Facing Servers (Static Source NAT)
- Configure Destination NAT with DNS Rewrite
- Configure Destination NAT Using Dynamic IP Addresses
- Modify the Oversubscription Rate for DIPP NAT
- Reserve Dynamic IP NAT Addresses
- Disable NAT for a Specific Host or Interface
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- Network Packet Broker Overview
- How Network Packet Broker Works
- Prepare to Deploy Network Packet Broker
- Configure Transparent Bridge Security Chains
- Configure Routed Layer 3 Security Chains
- Network Packet Broker HA Support
- User Interface Changes for Network Packet Broker
- Limitations of Network Packet Broker
- Troubleshoot Network Packet Broker
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- Enable Advanced Routing
- Logical Router Overview
- Configure a Logical Router
- Create a Static Route
- Configure BGP on an Advanced Routing Engine
- Create BGP Routing Profiles
- Create Filters for the Advanced Routing Engine
- Configure OSPFv2 on an Advanced Routing Engine
- Create OSPF Routing Profiles
- Configure OSPFv3 on an Advanced Routing Engine
- Create OSPFv3 Routing Profiles
- Configure RIPv2 on an Advanced Routing Engine
- Create RIPv2 Routing Profiles
- Create BFD Profiles
- Configure IPv4 Multicast
- Configure MSDP
- Create Multicast Routing Profiles
- Create an IPv4 MRoute
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PAN-OS 11.2
- PAN-OS 11.2
- PAN-OS 11.1
- PAN-OS 11.0 (EoL)
- PAN-OS 10.2
- PAN-OS 10.1
- PAN-OS 10.0 (EoL)
- PAN-OS 9.1 (EoL)
- PAN-OS 9.0 (EoL)
- PAN-OS 8.1 (EoL)
- Cloud Management and AIOps for NGFW
DHCP Leases
A lease is defined as the time period for which a DHCP
server allocates a network address to a client. The lease might
be extended (renewed) upon subsequent requests. If the client no
longer needs the address, it can release the address back to the
server before the lease is up. The server is then free to assign
that address to a different client if it has run out of unassigned
addresses.
The lease period configured for a DHCP server applies to all
of the addresses that a single DHCP server (interface) dynamically
assigns to its clients. That is, all of that interface’s addresses
assigned dynamically are of Unlimited duration
or have the same Timeout value. A different
DHCP server configured on the firewall may have a different lease
term for its clients. A Reserved Address is
a static address allocation and is not subject to the lease terms.
Per the DHCP standard, RFC 2131, a DHCP client
does not wait for its lease to expire, because it risks getting
a new address assigned to it. Instead, when a DHCP client reaches
the halfway point of its lease period, it attempts to extend its
lease so that it retains the same IP address. Thus, the lease duration
is like a sliding window.
Typically if an IP address was assigned to a device, the device
was subsequently taken off the network and its lease was not extended,
the DHCP server will let that lease run out. Because the client
is gone from the network and no longer needs the address, the lease
duration in the server is reached and the lease is in “Expired”
state.
The firewall has a hold timer that prevents the expired IP address
from being reassigned immediately. This behavior temporarily reserves
the address for the device in case it comes back onto the network.
But if the address pool runs out of addresses, the server re-allocates
this expired address before the hold timer expires. Expired addresses
are cleared automatically as the systems needs more addresses or
when the hold timer releases them.
In the CLI, use the show dhcp server lease operational
command to view lease information about the allocated IP addresses.
If you don’t want to wait for expired leases to be released automatically,
you can use the clear dhcp lease interface <interface> expired-only command
to clear expired leases, making those addresses available in the
pool again. You can use the clear dhcp lease interface <interface> ip <ip_address> command
to release a particular IP address. Use the clear dhcp lease interface <interface> mac <mac_address> command
to release a particular MAC address.