<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html><head><title>TLS-protected syslog: generating the machine certificate</title> </head> <body> <h1>Encrypting Syslog Traffic with TLS (SSL)</h1> <p><small><i>Written by <a href="http://www.adiscon.com/en/people/rainer-gerhards.php">Rainer Gerhards</a> (2008-06-18)</i></small></p> <ul> <li><a href="rsyslog_secure_tls.html">Overview</a> <li><a href="tls_cert_scenario.html">Sample Scenario</a> <li><a href="tls_cert_ca.html">Setting up the CA</a> <li><a href="tls_cert_machine.html">Generating Machine Certificates</a> <li><a href="tls_cert_server.html">Setting up the Central Server</a> <li><a href="tls_cert_client.html">Setting up syslog Clients</a> <li><a href="tls_cert_udp_relay.html">Setting up the UDP syslog relay</a> <li><a href="tls_cert_summary.html">Wrapping it all up</a> </ul> <h3>generating the machine certificate</h3> <p>In this step, we generate certificates for each of the machines. Please note that both clients and servers need certificates. The certificate identifies each machine to the remote peer. The DNSName specified inside the certificate can <span style="float: left"> <script type="text/javascript"><!-- google_ad_client = "pub-3204610807458280"; /* rsyslog doc inline */ google_ad_slot = "5958614527"; google_ad_width = 125; google_ad_height = 125; //--> </script> <script type="text/javascript" src="http://pagead2.googlesyndication.com/pagead/show_ads.js"> </script> </span> be specified inside the $<object>PermittedPeer config statements. <p>For now, we assume that a single person (or group) is responsible for the whole rsyslog system and thus it is OK if that single person is in posession of all machine's private keys. This simplification permits us to use a somewhat less complicated way of generating the machine certificates. So, we generate both the private and public key on the CA (which is NOT a server!) and then copy them over to the respective machines. <p>If the roles of machine and CA administrators are split, the private key must be generated by the machine administrator. This is done via a certificate request. This request is then sent to the CA admin, which in turn generates the certificate (containing the public key). The CA admin then sends back the certificate to the machine admin, who installs it. That way, the CA admin never get's hold of the machine's private key. Instructions for this mode will be given in a later revision of this document. <p><b>In any case, it is vital that the machine's private key is protected. Anybody able to obtain that private key can imporsonate as the machine to which it belongs, thus breaching your security.</b> <h3>Sample Screen Session</h3> <p>Text in red is user input. Please note that for some questions, there is no user input given. This means the default was accepted by simply pressing the enter key. <p><b>Please note:</b> you need to substitute the names specified below with values that match your environment. Most importantly, machine.example.net must be replaced by the actual name of the machine that will be using this certificate. For example, if you generate a certificate for a machine named "server.example.com", you need to use that name. If you generate a certificate for "client.example.com", you need to use this name. Make sure that each machine certificate has a unique name. If not, you can not apply proper access control. <code><pre> [root@rgf9dev sample]# <font color="red">certtool --generate-privkey --outfile key.pem --bits 2048</font> Generating a 2048 bit RSA private key... [root@rgf9dev sample]# <font color="red">certtool --generate-request --load-privkey key.pem --outfile request.pem</font> Generating a PKCS #10 certificate request... Country name (2 chars): <font color="red">US</font> Organization name: <font color="red">SomeOrg</font> Organizational unit name: <font color="red">SomeOU</font> Locality name: <font color="red">Somewhere</font> State or province name: <font color="red">CA</font> Common name: <font color="red">machine.example.net</font> UID: Enter a challenge password: [root@rgf9dev sample]# <font color="red">certtool --generate-certificate --load-request request.pem --outfile cert.pem --load-ca-certificate ca.pem --load-ca-privkey ca-key.pem</font> Generating a signed certificate... Enter the certificate's serial number (decimal): Activation/Expiration time. The certificate will expire in (days): 1000 Extensions. Does the certificate belong to an authority? (Y/N): <font color="red">n</font> Is this a TLS web client certificate? (Y/N): <font color="red">y</font> Is this also a TLS web server certificate? (Y/N): <font color="red">y</font> Enter the dnsName of the subject of the certificate: <font color="red">machine.example.net</font> <i>{This is the name of the machine that will use the certificate}</i> Will the certificate be used for signing (DHE and RSA-EXPORT ciphersuites)? (Y/N): Will the certificate be used for encryption (RSA ciphersuites)? (Y/N): X.509 Certificate Information: Version: 3 Serial Number (hex): 485a3819 Validity: Not Before: Thu Jun 19 10:42:54 UTC 2008 Not After: Wed Mar 16 10:42:57 UTC 2011 Subject: C=US,O=SomeOrg,OU=SomeOU,L=Somewhere,ST=CA,CN=machine.example.net Subject Public Key Algorithm: RSA Modulus (bits 2048): b2:4e:5b:a9:48:1e:ff:2e:73:a1:33:ee:d8:a2:af:ae 2f:23:76:91:b8:39:94:00:23:f2:6f:25:ad:c9:6a:ab 2d:e6:f3:62:d8:3e:6e:8a:d6:1e:3f:72:e5:d8:b9:e0 d0:79:c2:94:21:65:0b:10:53:66:b0:36:a6:a7:cd:46 1e:2c:6a:9b:79:c6:ee:c6:e2:ed:b0:a9:59:e2:49:da c7:e3:f0:1c:e0:53:98:87:0d:d5:28:db:a4:82:36:ed 3a:1e:d1:5c:07:13:95:5d:b3:28:05:17:2a:2b:b6:8e 8e:78:d2:cf:ac:87:13:15:fc:17:43:6b:15:c3:7d:b9 Exponent: 01:00:01 Extensions: Basic Constraints (critical): Certificate Authority (CA): FALSE Key Purpose (not critical): TLS WWW Client. TLS WWW Server. Subject Alternative Name (not critical): DNSname: machine.example.net Subject Key Identifier (not critical): 0ce1c3dbd19d31fa035b07afe2e0ef22d90b28ac Authority Key Identifier (not critical): fbfe968d10a73ae5b70d7b434886c8f872997b89 Other Information: Public Key Id: 0ce1c3dbd19d31fa035b07afe2e0ef22d90b28ac Is the above information ok? (Y/N): <font color="red">y</font> Signing certificate... [root@rgf9dev sample]# <font color="red">rm -f request.pem</font> [root@rgf9dev sample]# <font color="red">ls -l</font> total 16 -r-------- 1 root root 887 2008-06-19 12:33 ca-key.pem -rw-r--r-- 1 root root 1029 2008-06-19 12:36 ca.pem -rw-r--r-- 1 root root 1074 2008-06-19 12:43 cert.pem -rw-r--r-- 1 root root 887 2008-06-19 12:40 key.pem [root@rgf9dev sample]# # it may be a good idea to rename the files to indicate where they belong to [root@rgf9dev sample]# <font color="red">mv cert.pem machine-cert.pem</font> [root@rgf9dev sample]# <font color="red">mv key.pem machine-key.pem</font> [root@rgf9dev sample]# </pre></code> <h3>Distributing Files</h3> <p>Provide the machine with: <ul> <li>a copy of ca.pem <li>cert.pem <li>key.pem </ul> <p>This is how the relevant part of rsyslog.conf looks on the target machine: <p> <code><pre> $DefaultNetstreamDriverCAFile /home/rger/proj/rsyslog/sample/ca.pem $DefaultNetstreamDriverCertFile /home/rger/proj/rsyslog/sample/machine-cert.pem $DefaultNetstreamDriverKeyFile /home/rger/proj/rsyslog/sample/machine-key.pem </pre></code> <p><b><font color="red">Never</font> provide anyone with ca-key.pem!</b> Also, make sure nobody but the machine in question gets hold of key.pem. <h2>Copyright</h2> <p>Copyright (c) 2008 <a href="http://www.adiscon.com/en/people/rainer-gerhards.php">Rainer Gerhards</a> and <a href="http://www.adiscon.com/en/">Adiscon</a>.</p> <p> Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license can be viewed at <a href="http://www.gnu.org/copyleft/fdl.html">http://www.gnu.org/copyleft/fdl.html</a>.</p> </body></html>