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comzyh / clash

A rule-based tunnel in Go.
GNU General Public License v3.0
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Clash can only accept around 7k connections. #5

Closed comzyh closed 3 years ago

comzyh commented 4 years ago

Clash can only accept around 7k connections and then stop to accept a new TCP connection.

Analysis:

Clash set up a Forwarder to accept all new TCP connection https://github.com/comzyh/clash/blob/ab7da17a75c2626fcd49d3e69080fa6536391ddb/proxy/tun/tunproxy.go#L82-L97

According to gvisor netstack, netstack first check if there is an Endpoint match the incoming packet. If not, call the Forwarder I write. https://github.com/google/gvisor/blob/035f7434e978f3f246ae05e9c748e8ca7d8d7fd1/pkg/tcpip/stack/nic.go#L1301-L1311

For some reason, netstack keep the closed endpoint in the Endpoint map for a while after the connection is closed. At this time, if a new incoming connection reuses the same local-port, the TCP connection quadruple(srcIP, dstIP, srcPort, dstPort) matches the endpoints map. Then the Forwarder cannot receive the new incoming connection.

github-actions[bot] commented 3 years ago

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