Today, like the past few days, we have had some downtime. Apparently some script kids are enjoying themselves by targeting our server (and others). Sorry for the inconvenience.
Most of these โattacksโ are targeted at the database, but some are more ddos-like and can be mitigated by using a CDN. Some other Lemmy servers are using Cloudflare, so we know that works. Therefore we have chosen Cloudflare as CDN / DDOS protection platform for now. We will look into other options, but we needed something to be implemented asap.
For the other attacks, we are using them to investigate and implement measures like rate limiting etc.
They mean after adding a ddos mitigation like cloudflare, you should rotate the origin server IP so the origin serverโs IP is no longer publicly known and thus not directly reachable by ddos attackers. The only way to now interact with the application is though Cloudflareโs network. You should only have to do this once as long as the origin IP doesnโt publicly leak.
Another step would be to add firewall rules to only allow inbound traffic from cloudflare IPs: https://www.cloudflare.com/ips/
I recall a certain amount of overhead in IPTables โallow only fromโ situations but Iโm not sure whether itโs enough to make a DDOS any kind of viable on a server in this configuration.
Do you happen to know how effective the strategy is?
If your origin servers IP is never revealed then all traffic goes through cloudflare regardless. Firewall restricting the IPs is just good practice since cloudflare is the only IP that is supposed to talk to that server anyway, but itโs not a requirement.
I can see some overhead if youโre maintaining a large blacklist, but I donโt see it happening with a small whitelist and default inbound DROP
