Unable to bind source IP to send data

[vectorzjl]

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Issue description

There are multiple IP addresses on one network port. I want to specify the source IP address to send data. However, after I bind the interface using the bind interface, the traffic I see through packet capture still shows the default IP address, which is not the one I specified. What is the reason for this problem?

Environment

• libzmq version (commit hash if unreleased): 4.3.5
• OS: win11

Minimal test code / Steps to reproduce the issue

1. N/A

What's the actual result? (include assertion message & call stack if applicable)

N/A

What's the expected result?

I hope to specify the source IP to send data, and display the source IP address I specified in the actual captured data packet