Azure Virtual Network
An Azure networking service that is used to provision private networks and optionally to connect to on-premises datacenters.
2,252 questions
Certain IP Blocks being blocked that are hosted on Azure Cloud
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John Alcock
0
Reputation points
I am the Network Engineer with a small ISP in Tennessee.
Sites hosted on the Azure Cloud are not accessible. This started in the last 12 hours or so.
Some of my IP Blocks are ok, others are not. What is odd is that I can ping and trace route to them. I suspect this is most likely a filter of some type.
Example IP I am trying to reach
52.251.75.164
I can not get to it from 138.43.152.0/24 however, 143.55.254.0/24 can with no issues.
{count} votes
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Deepanshukatara-6769 6,715 Reputation points2024-06-28T05:48:20.58+00:00 Hi John , welcome to MS Q&A
Given that some of your IP blocks can access the Azure-hosted sites while others cannot, and considering that you can ping and trace route to the IPs, it does seem likely that there might be a network filter or access control list (ACL) in place that is affecting specific IP ranges.
Here are a few steps you can take to troubleshoot and potentially resolve the issue:
- Check Network Security Groups (NSGs): Ensure that the NSGs associated with the Azure resources are not blocking traffic from the affected IP ranges.
- Review Azure Firewall Rules: If you are using Azure Firewall, check the rules to ensure that the affected IP ranges are not being blocked.
- Verify Azure DDoS Protection: If Azure DDoS Protection is enabled, verify that it is not inadvertently blocking traffic from the affected IP ranges.
Kindly check and let us know if any further questions
Please accept answer , if it helps
Thanks
Deepanshu
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GitaraniSharma-MSFT 49,001 Reputation points Microsoft Employee2024-06-28T05:48:41.38+00:00 Hello @John Alcock ,
Welcome to Microsoft Q&A Platform. Thank you for reaching out & hope you are doing well.
I understand that you are unable to access some sites hosted in Azure from certain IP Blocks.
Could you please confirm if those Azure sites are hosted/owned by you?
The issue you're describing suggests that there might be a problem with routing or firewall rules specific to certain IP blocks.
If the Azure sites are hosted/owned by you, you could try the below steps to diagnose and potentially resolve the issue:
- Ensure that there are no misconfigured routing tables either within your network or on the Azure side that could be blocking traffic from the affected IP blocks.
- Check for any firewall rules that might be blocking traffic from the affected IP range (138.43.152.0/24) while allowing it from the other range (143.55.254.0/24).
- Check Azure NSG (Network Security Groups). Ensure that the NSG rules on Azure are not inadvertently blocking traffic from the affected IP range. Verify both inbound and outbound rules.
- Use Azure Network Watcher to check for any anomalies or blocked traffic in the diagnostic logs. This can help identify if Azure is blocking the traffic and why.
Refer: https://video2.skills-academy.com/en-us/azure/virtual-network/manage-route-table
https://video2.skills-academy.com/en-us/azure/virtual-network/network-security-groups-overview
https://video2.skills-academy.com/en-us/azure/network-watcher/ip-flow-verify-overview
Regards,
Gita
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