Core networking
probe.icloud.com and pong.icloud.com
probe.icloud.com and pong.icloud.com are Apple hosts for “iCloud connection testing”. Apple lists them for every platform, on port 443 over TCP and UDP.
Short answer
Apple's iCloud connection testing hosts.
Block with care
Blocking them may affect how Apple devices test their iCloud connection. Apple doesn't say what else depends on them.
- Matches
probe.icloud.compong.icloud.com
A name with *. covers every name under it: *.push.apple.com matches 1-courier.push.apple.com.
What it serves
Apple's enterprise host list names both in its iCloud section, with proxy support. Apple added them in January 2026.
Apple doesn't describe what the tests measure or how often devices run them.
Kilobat doesn't guess at more than Apple documents.
What breaks if you block it
Block with care
Blocking them may affect how Apple devices test their iCloud connection. Apple doesn't say what else depends on them.
What breaks if you block it
- iCloud connection tests fail. Apple doesn't document the effect on iCloud services.
With Kilobat Pro and the network filter, you can block a host for every app or for one app: in Connections, select a connection and choose Block. Apple’s own services are never blocked by Kilobat’s Protection lists.
Apple’s rules for its hosts
Apple’s list, Use Apple products on enterprise networks, says that devices open these connections, not Apple’s servers. Apple services fail any connection that uses HTTPS interception, so a proxy that inspects TLS should leave Apple’s hosts alone.
If a firewall allows hosts by name, allowing *.apple.com covers most Apple services, Apple says. A firewall that works only with addresses can allow 17.0.0.0/8 for IPv4, and 2403:300::/32, 2620:149::/32 and 2a01:b740::/32 for IPv6.
To see which app on your Mac opened a connection to this host, use Kilobat’s Connections tab, or the agent network log for AI agents.
Sources
Checked on 1 November 2026.