keepalives are an optional TCP feature so they are not necessarily supported by all TCP implementations and therefor default to off even when supported.
Where is it off? Most linux distros have it on it’s just the default kickoff timer is ridiculously long (like 2 hours iirc). Besides, TCP keepalives won't help with the issue at hand and were put in for totally different purpose (gc'ing idle connections). Most of the time you don't even need them because the other side will send RST packet if it already closed the socket.
You're conflating all optional TCP features of all operating systems, network devices, and RFCs together. This lack of nuance fails to appreciate that different applications have different needs for how they use TCP: ( server | client ) x ( one way | chatty bidirectional | idle tinygram | mixed ). If a feature needs to be used on a particular connection, then use it. ;)
If the feature already technically exists in TCP, it's either broken or disabled by default, which is pretty much the same as not having it.
keepalives are an optional TCP feature so they are not necessarily supported by all TCP implementations and therefor default to off even when supported.
Where is it off? Most linux distros have it on it’s just the default kickoff timer is ridiculously long (like 2 hours iirc). Besides, TCP keepalives won't help with the issue at hand and were put in for totally different purpose (gc'ing idle connections). Most of the time you don't even need them because the other side will send RST packet if it already closed the socket.
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So we need a protocol with some kind of non-optional default-enabled keepalive.
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You're conflating all optional TCP features of all operating systems, network devices, and RFCs together. This lack of nuance fails to appreciate that different applications have different needs for how they use TCP: ( server | client ) x ( one way | chatty bidirectional | idle tinygram | mixed ). If a feature needs to be used on a particular connection, then use it. ;)