SYN packets ignored over loopback

Solution Unverified - Updated -

Issue

  • SYN packets ignored for no obvious reason
  • Intermittent ignored and retransmitted SYNs for a specific connection 4-tuple when talking across the loopback device (127.0.0.1)
  • SYN retransmission over lo interface in to high-numbered LISTEN socket in local_port_range not in local_reserved_ports

Environment

  • Red Hat Enterprise Linux
  • TCP network communication
  • Loopback interface lo (IP address 127.0.0.1)

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