NPM with Vaultwarden and self signed cert won't work properly

[vvurzelsepp]

Hi all,
I have some problems with my NPM configuration. First a quick overview of what I have done so far:

1. Installed Vaultwarden via docker.
2. Since my instance should run in my local network only, I chose the method with a private CA and self signed certificates.
3. Configured a proxy in NPM for Vaultwarden.

On Linux and iOS (after importing the root CA) this works flawlessly. The first problem appeared with the macOS application. Once an API call is made, I get an pop up with a pretty generic network error message. I don't know how to trace this further and decided to ignore it for now, since I am mostly on Linux and can use the web app on macOS in the meantime.

In our household there's one person with an Android device, and with the official Bitwarden app I can't connect to the Vaultwarden server. Good thing is, here I can see a more verbose error message pop up:

Exception message: Read error: ssl=0xb40000762e35e188: Failure in SSL library, usually a protocol error
error:10000458:SSL routines:OPENSSL_internal:TLSV1_ALERT_UNRECOGNIZED_NAME(external/boringssl/src/ssl/tls_record.cc:594 0xb40000762d015248:0x000000001)

I didn't find much information about the UNRECOGNIZED_NAME error on the internet, and even looking at the source code hasn't helped a lot. I only found a reference in the extract_sni() function for this error in the file handshake_server.cc. So it seems like an error is happening on the server side of things while the TLS handshake is processed.

Then I used OpenSSL cli to check if everything is set up correctly:

openssl s_client -connect vaultwarden:443 -tls1_2 -tlsextdebug -status
CONNECTED(00000003)
001E68D9737F0000:error:0A000458:SSL routines:ssl3_read_bytes:tlsv1 unrecognized name:ssl/record/rec_layer_s3.c:1605:SSL alert number 112
---
no peer certificate available
---
No client certificate CA names sent
---
SSL handshake has read 7 bytes and written 197 bytes
Verification: OK
---
New, (NONE), Cipher is (NONE)
Secure Renegotiation IS NOT supported
Compression: NONE
Expansion: NONE
No ALPN negotiated
SSL-Session:
    Protocol  : TLSv1.2
    Cipher    : 0000
    Session-ID: 
    Session-ID-ctx: 
    Master-Key: 
    PSK identity: None
    PSK identity hint: None
    SRP username: None
    Start Time: 1681121486
    Timeout   : 7200 (sec)
    Verify return code: 0 (ok)
    Extended master secret: no
---

Here I get the same error (although in OpenSSL and not BoringSSL) I guess, but it seems like it's working nonetheless.
Now my guess is maybe something is not probably configured in NPM. All my internet searches boiled down to SNI and that it's maybe not setup correctly, but I don't know how to change this, as it seems as long as Nginx is compiled with SNI support, it should work out of the box.

Ultimately I tried out the following command, forcing OpenSSL to use SNI, and no error is propagated.
So I guess this is definitely the right direction, but I'm stuck here, since my DevOps skills are very limited.

openssl s_client -connect vaultwarden:443 -servername vaultwarden  -tls1_2 -tlsextdebug -status

CONNECTED(00000003)
TLS server extension "renegotiation info" (id=65281), len=1
0000 - 00                                                .
TLS server extension "server name" (id=0), len=0
TLS server extension "EC point formats" (id=11), len=4
0000 - 03 00 01 02                                       ....
TLS server extension "session ticket" (id=35), len=0
TLS server extension "extended master secret" (id=23), len=0
depth=1 C = DE, ST = Baden-Wuerttemberg, L = xxx, O = xxx, OU = Local Network, CN = vaultwarden
verify return:1
depth=0 C = DE, ST = Baden-Wuerttemberg, L = xxx, O = xxx, OU = vaultwarden, CN = vaultwarden
verify return:1
OCSP response: no response sent
---
Certificate chain
 0 s:C = DE, ST = Baden-Wuerttemberg, L = xxx, O = xxx, OU = vaultwarden, CN = vaultwarden
   i:C = DE, ST = Baden-Wuerttemberg, L = xxx, O = xxx, OU = Local Network, CN = vaultwarden
   a:PKEY: rsaEncryption, 2048 (bit); sigalg: RSA-SHA256
   v:NotBefore: Apr  9 16:49:00 2023 GMT; NotAfter: Apr  8 16:49:00 2024 GMT
 1 s:C = DE, ST = Baden-Wuerttemberg, L = xxx, O = xxx, OU = Local Network, CN = vaultwarden
   i:C = DE, ST = Baden-Wuerttemberg, L = xxx, O = xxx, OU = Local Network, CN = vaultwarden
   a:PKEY: rsaEncryption, 2048 (bit); sigalg: RSA-SHA256
   v:NotBefore: Apr  9 16:47:33 2023 GMT; NotAfter: Apr  8 16:47:33 2024 GMT
---
Server certificate
-----BEGIN CERTIFICATE-----
....
-----END CERTIFICATE-----
subject=C = DE, ST = Baden-Wuerttemberg, L = xxx, O = xxx, OU = vaultwarden, CN = vaultwarden
issuer=C = DE, ST = Baden-Wuerttemberg, L = xxx, O = xxx, OU = Local Network, CN = vaultwarden
---
No client certificate CA names sent
Peer signing digest: SHA256
Peer signature type: RSA-PSS
Server Temp Key: X25519, 253 bits
---
SSL handshake has read 2713 bytes and written 310 bytes
Verification: OK
---
New, TLSv1.2, Cipher is ECDHE-RSA-AES256-GCM-SHA384
Server public key is 2048 bit
Secure Renegotiation IS supported
Compression: NONE
Expansion: NONE
No ALPN negotiated
SSL-Session:
    Protocol  : TLSv1.2
    Cipher    : ECDHE-RSA-AES256-GCM-SHA384
    Session-ID: ...
    Session-ID-ctx: 
    Master-Key: ...
    PSK identity: None
    PSK identity hint: None
    SRP username: None
    TLS session ticket lifetime hint: 300 (seconds)
    TLS session ticket:
    0000 - 89 89 bd a9 65 aa 31 97-5e ba b0 67 ea f5 ae 8c   ....e.1.^..g....
    0010 - 2b f8 21 4a 1f 4f f6 6f-f0 1b 12 f8 77 e6 aa da   +.!J.O.o....w...
    0020 - 78 95 6b ee 72 0d 82 af-a5 fa 03 68 82 41 04 9d   x.k.r......h.A..
    0030 - 1f 81 78 2f 6d 23 da 52-46 2e 84 7e 94 d5 4c 4c   ..x/m#.RF..~..LL
    0040 - 92 63 bd a3 a6 e5 d9 1f-58 51 92 4e cb 4c 14 85   .c......XQ.N.L..
    0050 - cb 5d 2d fa 59 2a 93 32-36 3f a2 31 4a 2e 84 cf   .]-.Y*.26?.1J...
    0060 - 8f 44 b6 b1 fb 16 d4 66-8c 27 08 36 b3 ba a7 7a   .D.....f.'.6...z
    0070 - ec 7c 20 fe fa 93 9b 12-bc 46 bc dd 49 61 94 3d   .| ......F..Ia.=
    0080 - 64 c0 7f df 60 95 45 38-f4 41 84 99 c1 f5 5d 25   d...`.E8.A....]%
    0090 - 53 96 e8 26 30 e1 64 b3-7b b8 82 44 23 20 f4 a9   S..&0.d.{..D# ..
    00a0 - 33 cd 45 08 73 64 15 cc-3e 3a 03 8c ca 8f 41 ba   3.E.sd..>:....A.
    00b0 - f3 14 46 fe df f8 ee 18-55 e2 44 09 4b 24 af d6   ..F.....U.D.K$..

    Start Time: 1681124745
    Timeout   : 7200 (sec)
    Verify return code: 0 (ok)
    Extended master secret: yes
---
closed

Best regards
vvurzelsepp

[vvurzelsepp]

I got it to work. I ditched NPM and started to configure a custom Nginx docker container.

nginx.conf looks like this:

server {
   listen 443 ssl;
   server_name: vaultwarden;
   ssl_certificate: ssl/vaultwarden.crt;
   ssl_certificate_key: ssl/vaultwarden.key;

   location / {
      proxy_pass <IP-to-actual-vaultwarden-instance>;
   }
}

# further server configurations for more services
server {
 ....
}