[Bug]: Please consider whitelisting local and private IP ranges in malform traffic detection by default

[fakeboboliu]

Describe the bug you're experiencing

When the server relies on local programs or routers for forwarding and other processing,

blocking the IP address 127.0.0.1/192.168.0.1/etc can lead to destructive consequences (for example, blocking all join requests because they all originate from the same local/router IP address), and this may go unnoticed for a while (appearing only as a single line in the logs).

Connectivity was widely introduced for its analysis and repair features, and is described as a painless, problem-solving lightweight mod:

Lightweight mod which solves several connection problems like ....... It also offers commands to analyze network traffic and a bunch of debugging utilities, advanced error logging, packet logging etc.

However, the default intervention of this feature has led to many network-layer operations being incorrectly blocked, resulting in penalties for players.

Reproducability

Just forward the game port through the router, and soon everyone will be blocked

Mod up to date

• Before submitting this issue I updated to the newest version and reproduced it

Minecraft version

1.20.1

Modloader version

Forge

Logs

[co.co.Connectivity/]: Ignoring further traffic from: 127.0.0.1 for repeated malformed traffic.

[someaddons]

The config literally tells you to add proxy IPs or disable the feature. Also when you have repeated errors in your network something is going wrong.

[fakeboboliu]

I do see that the config provides the option, my suggestion is more about what the default (maybe generated default config so the users can alternate on purpose) should be.

Connectivity's strength is that it's a drop-in mod that fix things without requiring manual tuning. Most users won't dig into the config of a mod they installed for its "painless fix" reputation.

Having the feature (nearly) silently block all traffic from 127.0.0.1 or local IPs can be quite destructive in some common setups (NAT port forwarding, reverse proxy), and it's not easy to diagnose (for ordinary user).

Since loopback and private IP ranges are not considered as external sources (usually), defaulting them into the whitelist seems like a safe and reasonable change, it would protect the drop-in experience without weakening the feature's purpose for public internet threats.