TCP Settings
Table of Contents
Expand all | Collapse all
-
- Firewall Overview
- Features and Benefits
- Last Login Time and Failed Login Attempts
- Message of the Day
- Task Manager
- Language
- Alarms
- Commit Changes
- Save Candidate Configurations
- Revert Changes
- Lock Configurations
- Global Find
- Threat Details
- AutoFocus Intelligence Summary
- Configuration Table Export
- Change Boot Mode
-
- Objects > Addresses
- Objects > Address Groups
- Objects > Regions
- Objects > Dynamic User Groups
- Objects > Application Groups
- Objects > Application Filters
- Objects > Services
- Objects > Service Groups
- Objects > Devices
- Objects > External Dynamic Lists
- Objects > Custom Objects > Spyware/Vulnerability
- Objects > Custom Objects > URL Category
- Objects > Security Profiles > Antivirus
- Objects > Security Profiles > Anti-Spyware Profile
- Objects > Security Profiles > Vulnerability Protection
- Objects > Security Profiles > File Blocking
- Objects > Security Profiles > WildFire Analysis
- Objects > Security Profiles > Data Filtering
- Objects > Security Profiles > DoS Protection
- Objects > Security Profiles > Mobile Network Protection
- Objects > Security Profiles > SCTP Protection
- Objects > Security Profile Groups
- Objects > Log Forwarding
- Objects > Authentication
- Objects > Packet Broker Profile
- Objects > Schedules
-
-
- Firewall Interfaces Overview
- Common Building Blocks for Firewall Interfaces
- Common Building Blocks for PA-7000 Series Firewall Interfaces
- Tap Interface
- HA Interface
- Virtual Wire Interface
- Virtual Wire Subinterface
- PA-7000 Series Layer 2 Interface
- PA-7000 Series Layer 2 Subinterface
- PA-7000 Series Layer 3 Interface
- Layer 3 Interface
- Layer 3 Subinterface
- Log Card Interface
- Log Card Subinterface
- Decrypt Mirror Interface
- Aggregate Ethernet (AE) Interface Group
- Aggregate Ethernet (AE) Interface
- Network > Interfaces > VLAN
- Network > Interfaces > Loopback
- Network > Interfaces > Tunnel
- Network > Interfaces > SD-WAN
- Network > VLANs
- Network > Virtual Wires
-
- Network > Network Profiles > GlobalProtect IPSec Crypto
- Network > Network Profiles > IPSec Crypto
- Network > Network Profiles > IKE Crypto
- Network > Network Profiles > Monitor
- Network > Network Profiles > Interface Mgmt
- Network > Network Profiles > QoS
- Network > Network Profiles > LLDP Profile
- Network > Network Profiles > SD-WAN Interface Profile
-
-
- Device > Setup
- Device > Setup > Management
- Device > Setup > Interfaces
- Device > Setup > Telemetry
- Device > Setup > Content-ID
- Device > Setup > WildFire
- Device Setup Ace
- Device > Setup > DLP
- Device > Log Forwarding Card
- Device > Config Audit
- Device > Administrators
- Device > Admin Roles
- Device > Access Domain
- Device > Authentication Sequence
- Device > Device Quarantine
-
- Security Policy Match
- QoS Policy Match
- Authentication Policy Match
- Decryption/SSL Policy Match
- NAT Policy Match
- Policy Based Forwarding Policy Match
- DoS Policy Match
- Routing
- Test Wildfire
- Threat Vault
- Ping
- Trace Route
- Log Collector Connectivity
- External Dynamic List
- Update Server
- Test Cloud Logging Service Status
- Test Cloud GP Service Status
- Device > Virtual Systems
- Device > Shared Gateways
- Device > Certificate Management
- Device > Certificate Management > Certificate Profile
- Device > Certificate Management > OCSP Responder
- Device > Certificate Management > SSL/TLS Service Profile
- Device > Certificate Management > SCEP
- Device > Certificate Management > SSL Decryption Exclusion
- Device > Certificate Management > SSH Service Profile
- Device > Response Pages
- Device > Server Profiles
- Device > Server Profiles > SNMP Trap
- Device > Server Profiles > Syslog
- Device > Server Profiles > Email
- Device > Server Profiles > HTTP
- Device > Server Profiles > NetFlow
- Device > Server Profiles > RADIUS
- Device > Server Profiles > TACACS+
- Device > Server Profiles > LDAP
- Device > Server Profiles > Kerberos
- Device > Server Profiles > SAML Identity Provider
- Device > Server Profiles > DNS
- Device > Server Profiles > Multi Factor Authentication
- Device > Local User Database > Users
- Device > Local User Database > User Groups
- Device > Scheduled Log Export
- Device > Software
- Device > Dynamic Updates
- Device > Licenses
- Device > Support
- Device > Policy Recommendation > IoT
- Device > Policy > Recommendation SaaS
-
- Network > GlobalProtect > MDM
- Network > GlobalProtect > Clientless Apps
- Network > GlobalProtect > Clientless App Groups
- Objects > GlobalProtect > HIP Profiles
-
- Use the Panorama Web Interface
- Context Switch
- Panorama Commit Operations
- Defining Policies on Panorama
- Log Storage Partitions for a Panorama Virtual Appliance in Legacy Mode
- Panorama > Setup > Interfaces
- Panorama > High Availability
- Panorama > Administrators
- Panorama > Admin Roles
- Panorama > Access Domains
- Panorama > Device Groups
- Panorama > Plugins
- Panorama > Log Ingestion Profile
- Panorama > Log Settings
- Panorama > Server Profiles > SCP
- Panorama > Scheduled Config Export
- Panorama > Device Registration Auth Key
TCP Settings
The following table describes TCP settings.
TCP Settings | Description |
---|---|
Forward segments exceeding TCP out-of-order queue | Select this option if you want the firewall
to forward segments that exceed the TCP out-of-order queue limit
of 64 per session. If you disable this option, the firewall drops
segments that exceed the out-of-order queue limit. To see a count
of the number of segments that the firewall dropped as a result
of enabling this option, run the following CLI command:
show
counter global tcp_exceed_flow_seg_limit
This option is disabled
by default and should remain this way for the most secure deployment.
Disabling this option may result in increased latency for the specific
stream that received over 64 segments out of order. There should
be no loss of connectivity because the TCP stack should handle missing
segments retransmission. |
Allow Challenge ACK / Allow arbitrary ACK
in response to SYN | Enable this option to allow a response to
a challenge ACK (also known as an arbitrary ACK) for cases where
the server responds to the client SYN with an ACK instead of a SYN/ACK.
For example, challenge ACKs can be sent from the server for attack
mitigation purposes, and enabling this setting on the firewall allows
communication between the client and server so that the challenge
ACK process can be completed even when the handshake is out of state
or out of sequence. |
Drop segments with null timestamp option | The TCP timestamp records when the segment
was sent and allows the firewall to verify that the timestamp is
valid for that session, preventing TCP sequence number wrapping.
The TCP timestamp is also used to calculate round trip time. With
this option enabled, the firewall drops packets with null timestamps.
To see a count of the number of segments that the firewall dropped
as a result of enabling this option, run the following CLI command:
show
counter global tcp_invalid_ts_option
This option is enabled
by default and should remain this way for the most secure deployment.
Enabling this option should not result in performance degradation.
However, if a network stack incorrectly generates segments with
a null TCP timestamp option value, enabling this option may result
in connectivity issues. |
Asymmetric Path | Set globally whether to drop or bypass packets
that contain out-of-sync ACKs or out-of-window sequence numbers.
To control the setting
for individual Zone Protection Profiles, change the Asymmetric
Path setting in TCP Drop. |
Urgent Data Flag | Use this option to configure whether the
firewall allows the urgent pointer (URG bit flag) in the TCP header.
The urgent pointer in the TCP header is used to promote a packet
for immediate processing—the firewall removes it from the processing
queue and expedites it through the TCP/IP stack on the host. This
process is called out-of-band processing. Because the implementation
of the urgent pointer varies by host, setting this option to Clear (the
default and recommended setting) eliminates any ambiguity by disallowing out-of-band
processing so that the out-of-band byte in the payload becomes part
of the payload and the packet is not processed urgently. Additionally,
the Clear setting ensures that the firewall
sees the exact stream in the protocol stack as the host for whom the
packet is destined. To see a count of the number of segments in which
the firewall cleared the URG flag when this option is set to Clear,
run the following CLI command:
show
counter global tcp_clear_urg
By default, this flag
is set to Clear and should remain this way
for the most secure deployment. This should not result in performance
degradation; in the rare instance that applications, such as telnet,
are using the urgent data feature, TCP may be impacted. If you set
this flag to Do Not Modify, the firewall
allows packets with the URG bit flag in the TCP header and enables
out-of-band processing ( not recommended). |
Drop segments without flag | Illegal TCP segments without any flags set
can be used to evade content inspection. With this option enabled
(the default) the firewall drops packets that have no flags set
in the TCP header. To see a count of the number of segments that
the firewall dropped as a result of this option, run the following
CLI command:
show counter
global tcp_flag_zero
This option is enabled
by default and should remain this way for the most secure deployment.
Enabling this option should not result in performance degradation.
However, if a network stack incorrectly generates segments with
no TCP flags, enabling this option may result in connectivity issues. |
Strip MPTCP option | Enabled globally by default to convert (Multipath
TCP) MPTCP connections to standard TCP connections. To
allow MCTCP, change the Multipath TCP (MPTCP) Options setting
in TCP Drop. |
SIP TCP cleartext | Select one of the following options to set
the cleartext proxy behavior for SIP TCP sessions when a segmented
SIP header is detected.
|
TCP Retransmit Scan (PAN-OS 10.0.2
or later) | If enabled, the checksum for the original
packet is scanned when a retransmitted packet is seen. If the checksum
are different between the original and retransmitted packet, the
retransmitted packet is assumed to be malicious and dropped. |