09-21-2020 08:18 AM
Hi All
i have a scenario where the traffic works fine if it's forwarded by the routing table (and nat is applied)
when i used pbf, it didn't work, checking global counters i found oacket are dropped and the reason is "strict ip" option in the zone protection profile.
I run debug flow basic and got this message :
"source ip address in packet does not belong to interface address, packet dropped"
unchecking this option fixed the issue.
I did little research on this option and found it's releated to malformed packets not spoofing
we have spoofing check enabled but it's not affecting the operation (tried disabling it but everything is same)
So i see strict is making the spoof check but on the return traffic . Is that normal ?!
PAN OS 9.0.9-h1
Thanks!
09-22-2020 03:30 PM
The s2c traffic is dropping because of Strict IP is failing due to the source IP address is not routable over the exact ingress interface. The firewall decides if the address is routable by checking the routing table to see if a route exists for the server to use that interface.
Disabling Strict IP Address Check would allow the s2c traffic through the firewall, but it also introduces a security risk for that zone as well.
A better solution would be to add a route for the server address to use that interface. This would allow Strick IP Address Check can stay enabled and the routable check to succeed.
09-21-2020 12:41 PM
09-22-2020 12:15 AM
I couldn't see any document below , could you please share it.
For the PAN OS , customer is still running 9.0 , is this topic related to the upgrade to 9.1 ?
Thanks
09-22-2020 03:06 AM
Hi,
from the little infos you wrote on your problem i will say, you have a problem with the returning traffic.
just use "enforce symmetric return".
09-22-2020 03:09 AM
Hi @Abdul-Fattah Thanks for your reply . We tried already, result is same . We had to uncheck "strict ip" .
Why "strict ip" is affected by the routing,! isn't it for malfored packets/reserved IPs ,.. ?
09-22-2020 03:34 AM
as you can see below Stict Ip check can affect Incoming packets and match the error desc you were seeing
09-22-2020 06:18 AM
Not related to upgrade it is just suggestion.
Here is link to document
https://knowledgebase.paloaltonetworks.com/KCSArticleDetail?id=kA10g000000ClzeCAC
Regards
09-22-2020 06:22 AM
Hi @MP18 , thanks for your reply. Yes, spoofing is understanable but "IP strict" isn't
@Abdul-Fattah thanks for sharing the defination for "IP strict", but as per the defination, this might happen only on the ingress interface, for our case c2s is counting while s2c is zero, until we uncheck "strict ip"!
Thanks again
09-22-2020 06:27 AM - edited 09-22-2020 06:28 AM
Thats exactly what should happen.
Glade that it works now.
Good Luck.
09-22-2020 06:37 AM
@Abdul-Fattah yeah it already works with disabling "strict IP" so this is my question , why should i disable it ? even with the guide you shared it might only affect ingress interface
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