session_limit

session_limit limits UDP sessions, in total and per client IP. A session is a client address (ip:port) that sent a datagram within timeout. Datagrams of new sessions over the limit are dropped; existing sessions keep working.

server:
  udp:
    middlewares:
      sessions:
        session_limit:
          max: 10000
          max_per_ip: 50
          timeout: 1m

Field	Default	Description
max	0	Maximum sessions of the router, 0 is unlimited.
max_per_ip	0	Maximum sessions of a client IP, 0 is unlimited.
timeout	60s	A session without datagrams for this long ends.

At least max or max_per_ip is required. Dropped datagrams are logged at debug level.

Use it before load_balancer so one client cannot fill its max_sessions. Set timeout near the session_timeout of the load balancer.