3 ms·

The default ports are often blocked on such networks (public wifi, corporate firewalls, etc.), but also often open. 5222 is used by e.g. WhatsApp, 5223 is used

The default ports are often blocked on such networks (public wifi, corporate firewalls, etc.), but also often open. 5222 is used by e.g. WhatsApp, 5223 is used by e.g. Apple push notifications. So it's not as bad as it could be. But it's also totally possible to run XMPP over 443, and this is a feature of many popular XMPP deployments. If you're self-hosting, there are some guides for different deployment approaches here: https://wiki.xmpp.org/web/Tech_pages/XEP-0368 https://wiki.xmpp.org/web/Tech_pages/XEP-0368

toast0 1y ago
> 5222 is used by e.g. WhatsApp I left in 2019, but when I was there, WhatsApp used port 5222, but the client would try port 443 if port 5222 didn't work. After it had tried those enough, it would try on port 80 with HTTP wrappers. Really, the right model for a public service is what AOL did for AIM. Listen on all the ports. Clients should try on the 'proper' port, then 443, then 80, then random permutation. Skip certain ports because nobody likes it if you probe on smtp, smb, or chargen (etc)
- MattJ100 1y ago
  Yeah. I'd be surprised if Apple didn't use similar logic. XMPP can do multiple ports (a deployment can specify the recommended order in DNS). I've not heard of an all-ports deployment, but it does sound like an interesting experiment :)
  - toast0 1y ago
    Apple has a bit of an easier time, because they can (and do) lean on cellular carriers that restrict access to their push servers. And they have 17.0.0.0/8 But they say port 5223 and 2197 with fallback to 443 [1]. Google says 5228-5230 and 443, with a couple outliers [2]. [1] https://support.apple.com/en-us/102266 https://support.apple.com/en-us/102266 [2] https://support.google.com/work/android/answer/10513641?hl=en https://support.google.com/work/android/answer/10513641?hl=e...

3 ms·

The default ports are often blocked on such networks (public wifi, corporate firewalls, etc.), but also often open. 5222 is used by e.g. WhatsApp, 5223 is used

by MattJ100 1y ago

toast0 1y ago
> 5222 is used by e.g. WhatsApp I left in 2019, but when I was there, WhatsApp used port 5222, but the client would try port 443 if port 5222 didn't work. After it had tried those enough, it would try on port 80 with HTTP wrappers. Really, the right model for a public service is what AOL did for AIM. Listen on all the ports. Clients should try on the 'proper' port, then 443, then 80, then random permutation. Skip certain ports because nobody likes it if you probe on smtp, smb, or chargen (etc)
- MattJ100 1y ago
  Yeah. I'd be surprised if Apple didn't use similar logic. XMPP can do multiple ports (a deployment can specify the recommended order in DNS). I've not heard of an all-ports deployment, but it does sound like an interesting experiment :)
  - toast0 1y ago
    Apple has a bit of an easier time, because they can (and do) lean on cellular carriers that restrict access to their push servers. And they have 17.0.0.0/8 But they say port 5223 and 2197 with fallback to 443 [1]. Google says 5228-5230 and 443, with a couple outliers [2]. [1] https://support.apple.com/en-us/102266 https://support.apple.com/en-us/102266 [2] https://support.google.com/work/android/answer/10513641?hl=en https://support.google.com/work/android/answer/10513641?hl=e...