Support Support Downloads Knowledge Base Juniper Support Portal Community

Knowledge Base

Search our Knowledge Base sites to find answers to your questions.

Ask All Knowledge Base Sites All Knowledge Base Sites JunosE Defect (KA)Knowledge BaseSecurity AdvisoriesTechnical BulletinsTechnotes Sign in to display secure content and recently viewed articles

List of Screen Protections not applicable to 'Alarm without drop'

0

0

Article ID: KB11117 KB Last Updated: 26 Feb 2013Version: 8.0
Summary:
Some Screen Protection settings still drop attack packets, even though 'set zone <zone name> screen alarm-without-drop' is enabled.  
Symptoms:
Symptoms & Errors:
  • Some Screen Protection settings still drop attack packets, even though 'set zone <zone name> screen alarm-without-drop' is enabled.  
  • Does 'Generate Alarms without Dropping Packet' apply to all screen protection options?
  • Even with 'set zone <zone name> screen alarm-without-drop', some traffic is still being dropped while detecting some attacks.
  • The 'alarm-without-drop' setting is not working.

 
Cause:

Solution:

The 'Generate Alarms without Dropping Packet' option does not apply to the following Screen Protection settings:

    • SYN-ACK-ACK Proxy Protection
    • Mal-URL
    • Syn-Flood Protection detected by attack-threshold
Even with 'set zone screen alarm-without-drop' set, the traffic will be dropped while detecting the above attacks. This is the current design.

Also, in addition to the above Screen Protection settings, Alarm-without-drop does not apply to the following Screen Protection Settings on the ISG or NS5000 (high-end ASIC-Based platforms) when running NAT/Route mode.

    • ICMP Flood Protection
    • UDP Flood Protection
This is because in NAT/route mode, UDP and ICMP flood protection is enforced at the ASIC level on the ISG and NS5000 platform -- ISG1000, ISG2000, NS5200, and NS5400.
However, in Transparent mode, the UDP and ICMP flood protection is not performed in hardware, so Alarm-without-drop will work with a UDP/ICMP flood.

IMPORTANT NOTE:
If your firewall is running ScreenOS 5.4.0r8 and below, then packets may be dropped for the following Screen Protections too:
  • Source IP-based/Destination IP-based Session Limit
This is a bug and is fixed in ScreenOS 5.4.0r9 and later.
 

Related Links

Comment on this article > Affected Products Browse the Knowledge Base for more articles related to these product categories. Select a category to begin.

Getting Up and Running with Junos

Getting Up and Running with Junos Security Alerts and Vulnerabilities Product Alerts and Software Release Notices Problem Report (PR) Search Tool EOL Notices and Bulletins JTAC User Guide Customer Care User Guide Pathfinder SRX High Availability Configurator SRX VPN Configurator Training Courses and Videos End User Licence Agreement Global Search