Harden SSH Admission And Credential Input

src/ssh_transport.h

@@ -44,6 +44,17 @@ typedef struct {
     uint64_t handshake_timeouts;
     uint64_t authentication_attempts;
     uint64_t authentication_failures;
+    /* Admission is before work; completion above excludes denied requests and
+     * unsigned probes. All values are counts, never submitted identity data. */
+    uint64_t handshake_admissions;
+    uint64_t handshake_throttle_rejections;
+    uint64_t authentication_admissions;
+    uint64_t authentication_throttle_rejections;
+    uint64_t authentication_probe_admissions;
+    uint64_t authentication_probe_rejections;
+    uint64_t authentication_limit_disconnects;
+    uint64_t authentication_backend_errors;
+    uint64_t authentication_method_rejections;
     uint64_t request_rejections;
     uint64_t broker_connections;
     uint64_t broker_failures;