Nextcloud behind nginx reverse proxy error on iPhone and iPad

When publishing a nextcloud website using a nginx reverse proxy, you might get an error shown on Apple iOS iPhone and iPadOS iPads on all browsers - e.g. Safari or Chrome: ERR_CONNECTION_CLOSED

Solution

Add in the nginx reverse proxy configuration the following line:

proxy_hide_header Upgrade;

http://nginx.org/en/docs/http/ngx_http_proxy_module.html#proxy_hide_header 

By default, nginx does not pass the header fields “Date”, “Server”, “X-Pad”, and “X-Accel-...” from the response of a proxied server to a client. The proxy_hide_header directive sets additional fields that will not be passed. If, on the contrary, the passing of fields needs to be permitted, the proxy_pass_header directive can be used.

Syntax:	proxy_hide_header field;
Default:	—
Context:	http, server, location

Nginx GUI configuration:

1. Login to your Nginx Proxy Manager.
2. Open the 3 dots settings menu of the NextCloud host and select “Edit”
3. In the tab menu at the top of the window that has just opened select “Advanced” and insert the following in the “Custom Nginx Configuration” box:
   

   proxy_hide_header Upgrade;

4. Click "save". 

 

Source: https://help.nextcloud.com/t/nextcloud-behind-nginx-proxy-manager-and-safari-ios-macos-no-access/142234/13

iPhone iOS SMB CIFS connection

How to establish a SMB CIFS connection from your iOS device (iPhone or iPad), for example to your NAS storage system or some other network share:

1. Open the "files-app"
   
2. Select the three dots in the upper right corner
3. Select "connect to server" (in german "Mit Server verbinden"): 
4. Enter your SMB CIFS destination as IPv4 address or FQDN:

Apple iPhone/iPad iOS IPSec IKEv2 Proposals

When setting up VPN-tunnel from an Apple iPhone or iPad running iOS using IPSec with IKEv2 you need to know, which IPSec proposals the iPhone/iPad/iOS device are supporting/offering:

Offered proposals from iOS

Testing with an iPhone running iOS 12.4.1 and iPad 13.1.2:

• AES256-SHA256-DH14 (2048-bit MODP Group) <------ (✔ okay)
• AES256-SHA256-DH19 (256-bit random ECP group) <------ (✅ recommended)
• AES256-SHA256-DH5 (1536-bit MODP Group) <------ (❌not recommended)
• AES128-SHA1-DH2 (1024-bit MODP Group) <------ (❌not recommended)
• 3DES-SHA1-DH2 (1024-bit MODP Group) <------ (❌not recommended)

Recommendation

Therefore I recommened 🔒✅ to use for your IPSec IKEv2 proposals:

• IKEv2 Phase1: AES-CBC-256 with SHA2-256 and DH-Grp 19 (ECP 256bit)
• IKEv2 Phase2: AES-CBC-256 with SHA2-256 and DH-Grp 19 (ECP 256bit)

DH-Grp 19 ECP 256Bit > DH-Grp 14 RSA 2048Bit
-> For example see BSI recommendation for crypto IPSec page 13 section 3.2.4  or NIST recommendation page 9 line 264

-> Details for ECP (Elliptic Curve from NIST) for IKEv1/v2 see RFC5903 or IANA ipsec registry

Details to reverse engineering

iPhone iOS 12.4.1 IKEv2 RAW output:

2019-10-27 16:25:15.519164 ike 4: incoming proposal:
2019-10-27 16:25:15.519176 ike 4: proposal id = 1:
2019-10-27 16:25:15.519185 ike 4:   protocol = IKEv2:
2019-10-27 16:25:15.519195 ike 4:      encapsulation = IKEv2/none
2019-10-27 16:25:15.519205 ike 4:         type=ENCR, val=AES_CBC (key_len = 256)
2019-10-27 16:25:15.519215 ike 4:         type=INTEGR, val=AUTH_HMAC_SHA2_256_128
2019-10-27 16:25:15.519224 ike 4:         type=PRF, val=PRF_HMAC_SHA2_256
2019-10-27 16:25:15.519234 ike 4:         type=DH_GROUP, val=MODP2048.
2019-10-27 16:25:15.519246 ike 4: proposal id = 2:
2019-10-27 16:25:15.519255 ike 4:   protocol = IKEv2:
2019-10-27 16:25:15.519264 ike 4:      encapsulation = IKEv2/none
2019-10-27 16:25:15.519274 ike 4:         type=ENCR, val=AES_CBC (key_len = 256)
2019-10-27 16:25:15.519283 ike 4:         type=INTEGR, val=AUTH_HMAC_SHA2_256_128
2019-10-27 16:25:15.519293 ike 4:         type=PRF, val=PRF_HMAC_SHA2_256
2019-10-27 16:25:15.519303 ike 4:         type=DH_GROUP, val=ECP256.
2019-10-27 16:25:15.519314 ike 4: proposal id = 3:
2019-10-27 16:25:15.519323 ike 4:   protocol = IKEv2:
2019-10-27 16:25:15.519332 ike 4:      encapsulation = IKEv2/none
2019-10-27 16:25:15.519342 ike 4:         type=ENCR, val=AES_CBC (key_len = 256)
2019-10-27 16:25:15.519353 ike 4:         type=INTEGR, val=AUTH_HMAC_SHA2_256_128
2019-10-27 16:25:15.519365 ike 4:         type=PRF, val=PRF_HMAC_SHA2_256
2019-10-27 16:25:15.519374 ike 4:         type=DH_GROUP, val=MODP1536.
2019-10-27 16:25:15.519384 ike 4: proposal id = 4:
2019-10-27 16:25:15.519392 ike 4:   protocol = IKEv2:
2019-10-27 16:25:15.519400 ike 4:      encapsulation = IKEv2/none
2019-10-27 16:25:15.519408 ike 4:         type=ENCR, val=AES_CBC (key_len = 128)
2019-10-27 16:25:15.519416 ike 4:         type=INTEGR, val=AUTH_HMAC_SHA_96
2019-10-27 16:25:15.519424 ike 4:         type=PRF, val=PRF_HMAC_SHA
2019-10-27 16:25:15.519432 ike 4:         type=DH_GROUP, val=MODP1024.
2019-10-27 16:25:15.519443 ike 4: proposal id = 5:
2019-10-27 16:25:15.519451 ike 4:   protocol = IKEv2:
2019-10-27 16:25:15.519459 ike 4:      encapsulation = IKEv2/none
2019-10-27 16:25:15.519466 ike 4:         type=ENCR, val=3DES_CBC
2019-10-27 16:25:15.519474 ike 4:         type=INTEGR, val=AUTH_HMAC_SHA_96
2019-10-27 16:25:15.519482 ike 4:         type=PRF, val=PRF_HMAC_SHA
2019-10-27 16:25:15.519490 ike 4:         type=DH_GROUP, val=MODP1024.