NEFilterSocketFlow remoteHostname property

Question

Hi, i was wondering about the remoteHostname property of NEFilterSocketFlow that is available on macOS 11.0+. I have been doing some tests and I can never seem to get a value, it is always nil. I am looking at all flows from all apps. In what cases will this property show up?

Network Extension

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Posted by

santalvarez

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Answer 1

OK. If you get remoteEndpoint but not remoteHostname then there simply is no DNS name available. The doc comments associated with that property make it clear that this is a possibility:

Code Block  This property is only non-nil if the flow was created using Network.framework or NSURLSession.

Was the connection created by Network framework or NSURLSession (the latter includes Safari)?

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eskimo

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Answer 2

Can you get things to a point where remoteEndpoint gets populated?

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Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"

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eskimo

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Answer 3

Yes, I can get the remoteEndpoint populated

Code Block guard let socketFlow = flow as? NEFilterSocketFlow,
    let remoteEndpoint = socketFlow.remoteEndpoint as? NWHostEndpoint,
    let localEndpoint = socketFlow.localEndpoint as? NWHostEndpoint else {
      return nil
}
     
if #available(macOS 11.0, *) {
    if let hostname = socketFlow.remoteHostname {
        // Access hostname
    }
}

Posted by

santalvarez

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Answer 4

OK. If you get remoteEndpoint but not remoteHostname then there simply is no DNS name available. The doc comments associated with that property make it clear that this is a possibility:

Code Block  This property is only non-nil if the flow was created using Network.framework or NSURLSession.

Was the connection created by Network framework or NSURLSession (the latter includes Safari)?

Share and Enjoy
—
Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"

Posted by

eskimo

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NEFilterSocketFlow remoteHostname property

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