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Odd issue with internet access

alxl29 7 months ago

Hi,

I did several research and looked everywhere in the firewall, but I was not able to find an answer to my problem. Basically:

- I have an XGS126w with the latest OS

- The setup is fairly simple: 1 LAN on a private /24 subnet --> The Firewall --> Internet connection via the internet provider's gateway

- I set up a MASQ rule and ACL rule for the /24 subnet to access the internet, and but I still have no internet access

- However, as soon as I ping an internet target (like 8.8.8.8) from the firewall (Diagnostics -> Ping -> Ping 8.8.8.8 from my LAN interface), then the internet access starts working from my LAN.

- A few hours later, the LAN->internet access stops working again, and I have to ping an internet target from the firewall diagnostics tools again...

Did anyone see this issue before? I assume something happens when I ping 8.8.8 from the firewall, and I need to configure that thing in the firewall, but I can't figure out why... I'm happy to provide screenshots of my configuration if needed.

Many thanks for your help.

Alex

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0 Bharat J 7 months ago

Hi Alex

please post the firewall rule and Nat rules with gateway failover condition set along with current DDOS settings?

"Sophos Partner: Networkkings Pvt Ltd".

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0 alxl29 7 months ago in reply to Bharat J

Sure - this is the firewall rule:

NAT Rule:

DoS settings:

And my gateway details:
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0 rfcat_vk 7 months ago in reply to alxl29

What are you pinging in your test?

Ian

XG115W - v20.0.1 MR-1 - Home

XG on VM 8 - v20 GA

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0 alxl29 7 months ago in reply to rfcat_vk

8.8.8.8
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0 Bharat J 7 months ago in reply to alxl29

Add a new NAT rule and keep it on top for tshoot.

Regards

"Sophos Partner: Networkkings Pvt Ltd".

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0 alxl29 7 months ago in reply to Bharat J

Sure - I added the new rule and will wait until the issue happens again.
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0 alxl29 7 months ago in reply to alxl29

The issue occurred again, and my ping stopped working, the new rule didn't seem to have worked.
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0 emmosophos 7 months ago in reply to alxl29

Hello there,

If the issue persists, please open a case with Support and share the Case ID with us.

I recommend you do a pcap when the issue isn’t happening and one when the issue is happening so support can compare both captures.

Additionally, do a GUI Packet Capture, showing what firewall rules are hitting the traffic (when it is working) and do the same when the traffic stops working.

And finally, do a conntrack during both scenarios.

But it does sound like an issue with ARP, so you might want to check the connection between your Moden and the Sophos Firewall

That should help support get started with the investigation.

Regards,

Emmanuel (EmmoSophos)

Technical Team Lead, Global Community Support
Sophos Support Videos | Product Documentation | @SophosSupport | Sign up for SMS Alerts
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0 alxl29 7 months ago in reply to emmosophos

Emmanuel,

thanks for your response - I will follow those steps now.

Regards,
Alex
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0 Adam Dodge 7 months ago in reply to alxl29

You can also check the log viewer if the gateway was down during a specific time
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0 Adam Dodge 7 months ago in reply to alxl29

You can also check the log viewer if the gateway was down during a specific time
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0 alxl29 7 months ago in reply to Adam Dodge

thanks Adam.

When the issue occurs, I can reach the firewall from the internet (sophos central), and so the issue really "only" is that my LAN can't access the internet (even with a firewall rule and NAT MASQ rule).

Is there something else I can/should configure?

Regards,
Alex
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0 Bharat J 7 months ago in reply to alxl29

Create new test firewall rule from lan to wan keep on top of all firewall rules along with above suggested NAT rule for tshoot

"Sophos Partner: Networkkings Pvt Ltd".

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0 rfcat_vk 7 months ago in reply to alxl29

I would suggest you upgrade to v20.0 GA and see if the issue still persists.

Ian

XG115W - v20.0.1 MR-1 - Home

XG on VM 8 - v20 GA

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