Is there a definitive way to tell that rp_filter is dropping traffic (in this case echo request) other than disabling it and seeing the expected traffic (echo reply)? I tried an iptables packet trace but I either did it wrong or it showed nothing. The only indications I have right now are: No firewall rules blocking traffic but no replies either. The problem is subnet-specific (only occurs on a directly-connected subnet). Early Bird Extended! Save now until July 20 on the 2018 Momentum User Conference! Register here Leroy Tennison Network Information/Cyber Security Specialist E: leroy@xxxxxxxxxxxxxxxx 2220 Bush Dr McKinney, Texas 75070 www.datavoiceint.com TThis message has been sent on behalf of a company that is part of the Harris Operating Group of Constellation Software Inc. These companies are listed here . If you prefer not to be contacted by Harris Operating Group please notify us . This message is intended exclusively for the individual or entity to which it is addressed. This communication may contain information that is proprietary, privileged or confidential or otherwise legally exempt from disclosure. If you are not the named addressee, you are not authorized to read, print, retain, copy or disseminate this message or any part of it. If you have received this message in error, please notify the sender immediately by e-mail and delete all copies of the message. ��.n��������+%������w��{.n����j�\�)��jg��������ݢj����G�������j:+v���w�m������w�������h�����٥