[Swan] UPDATE Re: Authentication with pam_url and nonces

Mirsad Goran Todorovac mirsad.todorovac at alu.hr
Tue Feb 8 17:07:37 EET 2022


I get the error:

Feb  8 15:48:21 domac pamtester: pam_url(test:auth): TLSv1.3 (IN), TLS 
alert, unknown CA (560):
Feb  8 15:48:21 domac pamtester: pam_url(test:auth): OpenSSL SSL_read: 
error:14094418:SSL routines:ssl3_read_bytes:tlsv1 alert unknown ca, errno 0

and the certificates in pam_url.conf are the same as the working apache2 

         url         = 
"https://domac.alu.hr:443/cgi-bin/myauth-hmac.php"; # URI to fetch
         returncode  = "OK";                        # The remote 
script/cgi should return a 200 http code and this string as its only results
         userfield   = "user";                      # userfield name to send
         passwdfield = "pass";                      # passwdfield name 
to send
         extradata   = "&do=login";                 # extra data to send
         # prompt      = "Token: ";                   # password prompt

         verify_peer = true;                               # Verify peer?
         verify_host = true;                               # Make sure 
peer CN matches?
         client_cert = 
"/etc/ssl/certs/domac_alu_hr_wchain_20220110.pem";   # Client-side 
         client_key  = "/etc/ssl/private/domac_alu_hr_20220110.key"; # 
Client-side key
         ca_cert     = "/etc/ssl/certs/SectigoCA_20220110.pem"; # ca 
cert - defaults to ca-bundle.crt

I have verified the certs with "diff" and they are literally the same.
I am running out of options. Perhaps you have tested mTLS with pam_url?

I feel so tired, and it is only Tuesday. My weekend enthusiasm appears 
to have splashed :-(


On 2/8/2022 3:17 PM, Mirsad Goran Todorovac wrote:
> SSLVerifyClient did not exactly work out of the box on our apache2 
> server, and I don't have
> liberty to experiment with it ...
> pam_url with HMAC-SHA-2 just works, and I believe it has sound logic: 
> HMAC-SHA-256 protected the
> URL POST fields from tampering in the man-in-the-middle attacks and 
> the script return code.
> However, brute forcing CGI PHP script presents a problem, and mTLS 
> still seems like a way to do it, if only
> I could make it work for me.
> Mirsad
> On 2/7/2022 7:51 PM, Paul Wouters wrote:
>> If you feel the pam TLS calls needs more than server side cert 
>> verification, you should look into client authentication, eg mTLS. 
>> Don’t invent your own crypto.
>> Paul
Mirsad Goran Todorovac
CARNet sistem inženjer
Grafički fakultet | Akademija likovnih umjetnosti
Sveučilište u Zagrebu
CARNet system engineer
Faculty of Graphic Arts | Academy of Fine Arts
University of Zagreb, Republic of Croatia
tel. +385 (0)1 3711 451
mob. +385 91 57 88 355

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