[stunnel-users] Configuring Stunnel to work between client and server - possible certificate issue

[David Faizulaev]

Sorry but I've was incorrect.
The application cannot send or receive messages, I thought I was able to send messages, but I was wrong.

Best Regards,
David.



David Faizulaev | PL/SQL Developer | T  [phone] | M [phone]

Centralized OT Security Management for Distributed SCADA/ICS Networks

 Please consider the environment before printing this e-mail

-----Original Message-----
From: stunnel-users [mailto:stunnel-users-***@stunnel.org] On Behalf Of David Faizulaev
Sent: Tuesday, May 17, 2016 2:13 PM
To: stunnel-***@stunnel.org
Subject: Re: [stunnel-users] Configuring Stunnel to work between client and server - possible certificate issue

I see, I have a keystore file for the server, can it be set as KEY ? can I convert keystore to PEM?

Additionally, I've thought about configuring Stunnel in client mode.
Here is the configuration:

[custom]
client = yes
accept = 127.0.0.1:8449
connect = 192.168.220.72:444
verify = 2
CAfile = server.pem

In this case, my application appears to successfully connect to Stunnel & send messages.
But when it tries to access it in order to collect messages, it fails:

(App in C++)
Error: socketReceive data failed (Requested: 4 bytes, Cur chunk size: 4 bytes. Progress: Got: 0 bytes, Left: 4 bytes): System Err: An unknown error occurred while accessing an unnamed file.

Thank you for your assistance.

Best Regards,
David.



David Faizulaev | PL/SQL Developer | T  [phone] | M [phone]

Centralized OT Security Management for Distributed SCADA/ICS Networks

 Please consider the environment before printing this e-mail

-----Original Message-----
From: stunnel-users [mailto:stunnel-users-***@stunnel.org] On Behalf Of Ludolf Holzheid
Sent: Tuesday, May 17, 2016 2:03 PM
To: stunnel-***@stunnel.org
Subject: Re: [stunnel-users] Configuring Stunnel to work between client and server - possible certificate issue

Hello Ludolf,
I've printed the content of certificate file and the lines: "-----BEGIN CERTIFICATE-----" "-----END CERTIFICATE-----" exist.
In addition, I've compared the default certificate provided by Stunnel with the one I wish to use, they're structure is identical.

Hello David,

Please reply to the list, so others are able to comment too.

I don't know the 'default certificate provided by Stunnel'. I expect it to be depending on the distribution.

However, if there are "BEGIN/END CERTIFICATE" lines in your file, but no "BEGIN/END RSA PRIVATE KEY", then the file is in PEM format, but the key is missing. Maybe you have separate files for private key and certificate. If this is the case, you may either concatenate key and certificate to a single file or specify both files in the stunnel

key = my-private-key.pem
cert = my-certificate.pem

Ludolf

--

Ludolf Holzheid
 
Bihl+Wiedemann GmbH
Floßwörthstraße 41
68199 Mannheim, Germany
 
Tel: [phone]
Fax: [phone]
 
mailto:***@bihl-wiedemann.de
http://www.bihl-wiedemann.de
 
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Geschäftsführer: Jochen Bihl, Bernhard Wiedemann Amtsgericht Mannheim, HRB 5796 _______________________________________________
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[Ludolf Holzheid]

Post by David Faizulaev
I see, I have a keystore file for the server, can it be set as KEY ? can I convert keystore to PEM?

I don't know.

Some key/certificate repositories don't allow to export private keys.
Maybe there is a PKCS11 plug-in for OpenSSL to access the keystore.
If this is the case, you don't have to export your private key. But
again, I don't know.

Post by David Faizulaev
Additionally, I've thought about configuring Stunnel in client mode.
[..]

Running stunnel in client or server mode makes no difference
w.r.t. certificate and key files. As long as stunnel is not able to
access your private key, the client mode won't work either.

HTH,

Ludolf
--
Ludolf Holzheid
 
Bihl+Wiedemann GmbH
Floßwörthstraße 41
68199 Mannheim, Germany
 
Tel: [phone]
Fax: [phone]
 
mailto:***@bihl-wiedemann.de
http://www.bihl-wiedemann.de
 
Sitz der Gesellschaft: Mannheim
Geschäftsführer: Jochen Bihl, Bernhard Wiedemann
Amtsgericht Mannheim, HRB 5796

[Ludolf Holzheid]

After further investigation, it became evident that Stunnel should run as client.
Therefore, I've converted my existing certs file (from my application) into a PEM file.
The file includes -----BEGIN CERTIFICATE----- & -----END CERTIFICATE-----.
2016.05.17 15:57:24 LOG4[281]: CERT: Pre-verification error: self signed certificate in certificate chain
2016.05.17 15:57:24 LOG4[281]: Rejected by CERT at depth=1: CN=NextnineCA
2016.05.17 15:57:24 LOG3[281]: SSL_connect: 14090086: error:14090086:SSL routines:ssl3_get_server_certificate:certificate verify failed
[custom]
client = yes
accept = 127.0.0.1:8449
connect = 192.168.220.62:443
verify = 2
CAfile = myapp.pem

David,

CAfile should point to a list of trusted certificates. The file(s)
for your pair of certificate and key should be specified with
cert=... (and key=..., if certificate and key are stored to separate
files).

Are the log messages generated at stunnel startup or at connection
establishment?

Ludolf
--
Ludolf Holzheid
 
Bihl+Wiedemann GmbH
Floßwörthstraße 41
68199 Mannheim, Germany
 
Tel: [phone]
Fax: [phone]
 
mailto:***@bihl-wiedemann.de
http://www.bihl-wiedemann.de
 
Sitz der Gesellschaft: Mannheim
Geschäftsführer: Jochen Bihl, Bernhard Wiedemann
Amtsgericht Mannheim, HRB 5796

[Ludolf Holzheid]

Logs messages are generated upon connection attempt.

Then the server presents a certificate that can't be validated against
the trusted certificates stored to the file you specified with
CAfile=...

Ludolf
--
Ludolf Holzheid
 
Bihl+Wiedemann GmbH
Floßwörthstraße 41
68199 Mannheim, Germany
 
Tel: [phone]
Fax: [phone]
 
mailto:***@bihl-wiedemann.de
http://www.bihl-wiedemann.de
 
Sitz der Gesellschaft: Mannheim
Geschäftsführer: Jochen Bihl, Bernhard Wiedemann
Amtsgericht Mannheim, HRB 5796

[Ludolf Holzheid]

Bag Attributes
friendlyName: trustcenterclass2caii
2.16.840.1.113894.746875.1.1: <Unsupported tag 6>
subject=/C=DE/O=TC TrustCenter GmbH/OU=TC TrustCenter Class 2 CA/CN=TC TrustCenter Class 2 CA II
issuer=/C=DE/O=TC TrustCenter GmbH/OU=TC TrustCenter Class 2 CA/CN=TC TrustCenter Class 2 CA II
possible cause?

No, this should be ignored as a comment.

But you instructed stunnel to check the peer's certificate against the
trusted ones (verify = 2), and the certificate chain the peer presents
ends with a certificate not found in the CA file.

Ludolf
--
Ludolf Holzheid
 
Bihl+Wiedemann GmbH
Floßwörthstraße 41
68199 Mannheim, Germany
 
Tel: [phone]
Fax: [phone]
 
mailto:***@bihl-wiedemann.de
http://www.bihl-wiedemann.de
 
Sitz der Gesellschaft: Mannheim
Geschäftsführer: Jochen Bihl, Bernhard Wiedemann
Amtsgericht Mannheim, HRB 5796

[Ludolf Holzheid]

Hello,
2016.05.17 16:40:25 LOG3[285]: SSL_connect: 14090086: error:14090086:SSL routines:ssl3_get_server_certificate:certificate verify failed
2016.05.17 16:40:25 LOG5[285]: Connection reset: 0 byte(s) sent to SSL, 0 byte(s) sent to socket
2016.05.17 16:40:25 LOG4[285]: Possible memory leak at .\crypto\asn1\tasn_new.c:179: 11859 allocations
2016.05.17 16:40:25 LOG4[285]: Possible memory leak at .\crypto\asn1\asn1_lib.c:408: 11241 allocations

Strange. I never used verify = 0, but I had the understanding,
stunnel should accept a connection even if the peer's certificate
can't be verified.

Anyhow, what happens if you add the self-signed certificate presented
by the peer to the CA file?

Ludolf
--
Ludolf Holzheid
 
Bihl+Wiedemann GmbH
Floßwörthstraße 41
68199 Mannheim, Germany
 
Tel: [phone]
Fax: [phone]
 
mailto:***@bihl-wiedemann.de
http://www.bihl-wiedemann.de
 
Sitz der Gesellschaft: Mannheim
Geschäftsführer: Jochen Bihl, Bernhard Wiedemann
Amtsgericht Mannheim, HRB 5796

[Ludolf Holzheid]

Do you concatenate the self-signed certificate to the current CA?

This self-signed certificate /is/ the current CA certificate, as it is
the root of the peer's certificate chain and you trust it.

Ludolf
--
Ludolf Holzheid
 
Bihl+Wiedemann GmbH
Floßwörthstraße 41
68199 Mannheim, Germany
 
Tel: [phone]
Fax: [phone]
 
mailto:***@bihl-wiedemann.de
http://www.bihl-wiedemann.de
 
Sitz der Gesellschaft: Mannheim
Geschäftsführer: Jochen Bihl, Bernhard Wiedemann
Amtsgericht Mannheim, HRB 5796