Hi,

Port  4500 is the IPSec UDP nat port and 500 is IKE.

Anyconnect uses ISPEC so I think those ports are simply in use.


--John

On 24/09/19 9:36 PM, wireguard@p-np.de wrote:
> Hello,
>
> in place upgrades from iOS 12 -> iOS 13 (release) seem to work well in 
> general. But there is a bizarre issue depending on *remote* endpoint 
> ports. If you have, in my case, 4500/UDP configured as remote endpoint 
> the tunnel does not send or receive traffic. Changing it to any other 
> port works. Changing back to 4500/UDP breaks it again reproducibly. 
> For others, documented here 
> <https://www.reddit.com/r/WireGuard/comments/d6in39/wg_broken_on_ios_13/> , 
> it is 1500/UDP, in #WireGuard there has been a documented issue for 
> 500/UDP not working.
>
> I have AnyConnect installed in parallel and checked, whether that's 
> related. But removing and resetting Network settings did not fix port 
> 4500 for me.
>
> As there is no port number dependent branching in the WireGuard-iOS 
> code base, this is likely an iOS regression. Does any one of you have 
> a working channel to Apple to report this?
>
> Thank you for an else excellent product. Let me know if I can be of 
> any help.
>
> Best regards,
>
> Christian
>
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