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<p class="MsoNormal"><span lang="EN-CA" style="font-size:11.0pt;font-family:"Calibri",sans-serif">Hi Attila,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-CA" style="font-size:11.0pt;font-family:"Calibri",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal" style="margin-left:36.0pt"><i><span style="color:gray">The trusted-dn() option is used for an additional verification step to reject clients/servers<o:p></o:p></span></i></p>
<p class="MsoNormal"><span lang="EN-CA" style="font-size:11.0pt;font-family:"Calibri",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-CA" style="font-size:11.0pt;font-family:"Calibri",sans-serif">Ah, OK, yes, I think I misread (or misinterpreted) this. I get how this is used now, thx.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-CA" style="font-size:11.0pt;font-family:"Calibri",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal" style="margin-left:36.0pt"><i><span style="color:gray">Could you kindly confirm that this is what you are looking for?<o:p></o:p></span></i></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span lang="EN-CA" style="font-size:11.0pt;font-family:"Calibri",sans-serif">Yes, exactly. This is similar to what (for e.g.) the SSLCACertificate{File|Path} mod_ssl directives are used for with the Apache HTTP Server and its HTTPS operation
(see <a href="https://httpd.apache.org/docs/2.4/mod/mod_ssl.html">https://httpd.apache.org/docs/2.4/mod/mod_ssl.html</a>). Without this connecting clients aren’t given any hints that can help them provide a proper client certificate (when they otherwise have
many to choose from, each possibly signed by different CAs).<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-CA" style="font-size:11.0pt;font-family:"Calibri",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-CA" style="font-size:11.0pt;font-family:"Calibri",sans-serif">Thanks,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-CA" style="font-size:11.0pt;font-family:"Calibri",sans-serif">-David<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-CA" style="font-size:11.0pt;font-family:"Calibri",sans-serif"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> syslog-ng <syslog-ng-bounces@lists.balabit.hu>
<b>On Behalf Of </b>Attila Szakács<br>
<b>Sent:</b> Thursday, March 30, 2023 3:12 AM<br>
<b>To:</b> Syslog-ng users' and developers' mailing list <syslog-ng@lists.balabit.hu><br>
<b>Subject:</b> Re: [syslog-ng] TLS "trusted-dn" Question<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Hi David, <o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">The trusted-dn() option is used for an additional verification step to reject clients/servers, which provide a cert having such a <b>subject</b> field that does not match with any of the patterns set in trusted-dn().<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Unfortunately, I think that the first sentence in the documentation is a bit misleading:<o:p></o:p></p>
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<p class="MsoNormal"><i>Description: To accept connections only from hosts using certain certificates signed by the trusted CAs, list the distinguished names of the accepted certificates in this parameter. For example, using trusted-dn("*, O=Example Inc, ST=Some-State,
C=*") will accept only certificates issued for the Example Inc organization in Some-State state.</i><o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">If I understand correctly, what you would like to achieve is defined in <a href="https://usg02.safelinks.protection.office365.us/?url=https%3A%2F%2Fwww.ietf.org%2Frfc%2Frfc5246.txt&data=05%7C01%7Cdavidh%40netacquire.com%7C4d2481e9962047dc420d08db31073b8e%7Cec65e18eede24cedbdab49355e3f602d%7C0%7C0%7C638157679363439549%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=wL9mYnHT0wDAWeUPj1DCRdF1DcwQUpguUech2vhKb7s%3D&reserved=0">https://www.ietf.org/rfc/rfc5246.txt</a>
-> <span style="color:black">7.4.4. Certificate Request:</span><o:p></o:p></p>
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<pre style="white-space:pre-wrap"><span style="color:black"> certificate_authorities<o:p></o:p></span></pre>
<pre><span style="color:black"> A list of the distinguished names [X501] of acceptable<o:p></o:p></span></pre>
<pre><span style="color:black"> certificate_authorities, represented in DER-encoded format. These<o:p></o:p></span></pre>
<pre><span style="color:black"> distinguished names may specify a desired distinguished name for a<o:p></o:p></span></pre>
<pre><span style="color:black"> root CA or for a subordinate CA; thus, this message can be used to<o:p></o:p></span></pre>
<pre><span style="color:black"> describe known roots as well as a desired authorization space. If<o:p></o:p></span></pre>
<pre><span style="color:black"> the certificate_authorities list is empty, then the client MAY<o:p></o:p></span></pre>
<pre><span style="color:black"> send any certificate of the appropriate ClientCertificateType,<o:p></o:p></span></pre>
<pre><span style="color:black"> unless there is some external arrangement to the contrary.<o:p></o:p></span></pre>
<pre style="white-space:pre-wrap"><span style="color:black"><o:p> </o:p></span></pre>
<pre style="white-space:pre-wrap"><span style="font-family:"Arial",sans-serif;color:#222222">This is not implemented in syslog-ng, yet, but it could be done easily with </span><span style="font-family:"Arial",sans-serif;color:black"><a href="https://usg02.safelinks.protection.office365.us/?url=https%3A%2F%2Fwww.openssl.org%2Fdocs%2Fman3.0%2Fman3%2FSSL_get0_CA_list.html&data=05%7C01%7Cdavidh%40netacquire.com%7C4d2481e9962047dc420d08db31073b8e%7Cec65e18eede24cedbdab49355e3f602d%7C0%7C0%7C638157679363439549%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=v1Hbhcgm4Bf2zw0AYF6%2F177xXLXxjkU5HhwLPCBfDS0%3D&reserved=0">SSL_set_client_CA_list()</a>:<o:p></o:p></span></pre>
<pre><i><span style="font-family:"Arial",sans-serif;color:black">SSL_set_client_CA_list() sets the list of CAs sent to the client when requesting a client certificate for the chosen ssl, overriding the setting valid for ssl's SSL_CTX object.</span></i><span style="color:black"><o:p></o:p></span></pre>
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<p class="MsoNormal"><span style="color:black">Could you kindly confirm that this is what you are looking for?</span><o:p></o:p></p>
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<p class="MsoNormal"><span style="color:black"><br>
<br>
</span><o:p></o:p></p>
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<p class="MsoNormal"><span style="color:black">Cheers,</span><o:p></o:p></p>
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<p class="MsoNormal"><span style="color:black">Attila</span><o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">On Wed, Mar 29, 2023 at 8:42 PM David Hauck <<a href="mailto:davidh@netacquire.com">davidh@netacquire.com</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt">Hi,<br>
<br>
I'm currently using syslog-ng OSE v3.31.2 and trying to get a TLS configured endpoint to use the 'trusted-dn()' TLS option. I'm having trouble getting syslog-ng to return these DN specifiers in the Certificate Request option during the TLS negotiation so that
clients can properly condition their supplied client certificates. <br>
<br>
I invariably see the following TLS negotiations (empty DNs list) in my Wireshark captures (as returned by the syslog-ng server):<br>
<br>
TLSv1.2 Record Layer: Handshake Protocol: Certificate Request<br>
Content Type: Handshake (22)<br>
Version: TLS 1.2 (0x0303)<br>
Length: 58<br>
Handshake Protocol: Certificate Request<br>
Handshake Type: Certificate Request (13)<br>
Length: 54<br>
Certificate types count: 3<br>
Certificate types (3 types)<br>
Signature Hash Algorithms Length: 46<br>
Signature Hash Algorithms (23 algorithms)<br>
Distinguished Names Length: 0 <----- always '0'<br>
<br>
In these cases my clients choose random client certificates that can't be refined to certificates signed by those expected (via the 'trusted-dn()' values) by the server and the connection is immediately closed.<br>
<br>
Here's the syslog-ng.conf entry for these sources:<br>
<br>
source s_515_tls {<br>
network( transport(tls) port(515) ip-protocol(6)<br>
tls(ca-dir("/etc/ssl/certs") key-file("/root/naservers.key") cert-file("/root/naservers.cer")<br>
peer-verify(required-trusted) trusted-dn("CN=*.<a href="https://usg02.safelinks.protection.office365.us/?url=http%3A%2F%2Fnetacquire.com%2F&data=05%7C01%7Cdavidh%40netacquire.com%7C4d2481e9962047dc420d08db31073b8e%7Cec65e18eede24cedbdab49355e3f602d%7C0%7C0%7C638157679363439549%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=X5NIUWuYD5F4GQ6WbnW%2F5HMrjJFkeg%2Fh4ma9xUMdN8w%3D&reserved=0" target="_blank">netacquire.com</a>"))
); <br>
};<br>
<br>
I've tried several variants of the 'trusted-dn()' values, including other wildcards for country, state, etc. I always see a DNs list of zero size in the TLS Certificate Request option returned by the server. As expected switching to 'peer-verify(required-untrusted)'
results in successful negotiation (with expected server-side errors indicating problems associated with the client certificates) and subsequent successful client/server logging.<br>
<br>
I figure I must be missing something obvious ;). Any ideas?<br>
<br>
Here's my syslog-ng version info:<br>
<br>
[logdest:~]# syslog-ng --version<br>
syslog-ng 3 (3.31.2)<br>
Config version: 3.29<br>
Installer-Version: 3.31.2<br>
Revision:<br>
Compile-Date: Nov 9 2021 12:52:59<br>
Module-Directory: /usr/lib/syslog-ng<br>
Module-Path: /usr/lib/syslog-ng<br>
Include-Path: /usr/share/syslog-ng/include<br>
Available-Modules: tfgetent,mod-python,cryptofuncs,hook-commands,kvformat,cef,afuser,linux-kmsg-format,map-value-pairs,system-source,azure-auth-header,csvparser,affile,afprog,secure-logging,http,examples,timestamp,afsocket,confgen,stardate,dbparser,xml,disk-buffer,appmodel,afsnmp,add-contextual-data,afstomp,graphite,json-plugin,basicfuncs,syslogformat,pseudofile,tags-parser<br>
Enable-Debug: off<br>
Enable-GProf: off<br>
Enable-Memtrace: off<br>
Enable-IPv6: on<br>
Enable-Spoof-Source: off<br>
Enable-TCP-Wrapper: on<br>
Enable-Linux-Caps: on<br>
Enable-Systemd: off<br>
<br>
Thanks,<br>
-David<br>
______________________________________________________________________________<br>
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