mod_s2s_keepalive: Ignore errors from the local server If a stanza can't be delivered and instead an bounce is generated, the origin of the error, when different from the stanza 'from' should be indicated in the 'by' attribute of the <error>, which we look for here so this doesn't count as a successful ping. An error that does come from the remote means we have connectivity, but probably no XEP-0199 handling. This is fine. We care about connectivity, not protocol.

This module implements the [Server
Optimization](https://xmpp.org/extensions/xep-0410.html#serveroptimization)
part of [XEP-0410: MUC Self-Ping]

# Usage

The module is loaded on MUC components:

```lua
Component "muc.example.com" "muc"
modules_enabled = {
    "muc_ping";
}
```

# Configuration

No options.

# Compatibility

It should work with Prosody up until 0.10.x.

Prosody 0.11.x and trunk natively supports XEP-0410 so this module is **not** needed.