As others have suggested you can try to fight back depending on the capabilities of your infrastructure. All crawlers will have some kind of queuing system. If you manage to cause for the queues to fill up then the crawler wont be able to send as many requests. For example, you can allow the crawler to open the socket but you only send the data very slowly causing the queues to get filled quickly with busy workers.
Depending on how the crawler is designed this may or may not work. If they are using SQS with Lambda then that will obviously not work but it will fire back nevertheless because the serverless functions will be running for longer (5 - 15 minutes).
Another technique that comes to mind is to try to force the client to upgrade the connection (i.e. websocket). See what will happen. Mostly it will fail but even if it gets stalled for 30 seconds that is a win.
Depending on how the crawler is designed this may or may not work. If they are using SQS with Lambda then that will obviously not work but it will fire back nevertheless because the serverless functions will be running for longer (5 - 15 minutes).
Another technique that comes to mind is to try to force the client to upgrade the connection (i.e. websocket). See what will happen. Mostly it will fail but even if it gets stalled for 30 seconds that is a win.