ICMP Type 3 Packets Blocked Unexpectedly After 14.3 RU10 Upgrade

Products

• Endpoint Security
• Endpoint Security Complete

Issue/Introduction

After upgrading from SEP 14.3 RU10 to SEP 16 you notice that ICMP traffic gets blocked unexpectedly.  When attempting to Remote Desktop (RDP) from a system a different subnet to another host you notice it no longer works.

Environment

Symantec Endpoint Protection 16 (SEP 16)
Endpoint Security Agent (ESA)  v2.8.0.31
Symantec Endpoint Security (SES)

Cause

The default firewall policy for SEP 16 agents blocks ICMP type 3 packets unexpectedly because there is no firewall rule to allow this traffic.  

Resolution

This is a known issue and we will address this in a future release.  

Workaround: 
Add a temporary Allow All rule for ICMP traffic (Type 3, Code 4) at the top of your firewall rules list and save your changes.  

 

Additional Information

CRE-24142