2 \section*{Bacula TLS -- Communications Encryption}
4 \index[general]{TLS -- Communications Encryption}
5 \index[general]{Communications Encryption}
6 \index[general]{Encryption!Communications}
7 \index[general]{Encryption!Transport}
8 \index[general]{Transport Encryption}
10 \addcontentsline{toc}{section}{TLS -- Communications Encryption}
12 Bacula TLS (Transport Layer Security) is built-in network
13 encryption code to provide secure network transport similar to
14 that offered by {\bf stunnel} or {\bf ssh}. The data written to
15 Volumes by the Storage daemon is not encrypted by this code.
16 For data encryption, please see the \ilink{Data Encryption
17 Chapter}{DataEncryption} of this manual.
19 The Bacula encryption implementations were written by Landon Fuller.
21 Supported features of this code include:
23 \item Client/Server TLS Requirement Negotiation
24 \item TLSv1 Connections with Server and Client Certificate
26 \item Forward Secrecy Support via Diffie-Hellman Ephemeral Keying
29 This document will refer to both "server" and "client" contexts. These
30 terms refer to the accepting and initiating peer, respectively.
32 Diffie-Hellman anonymous ciphers are not supported by this code. The
33 use of DH anonymous ciphers increases the code complexity and places
34 explicit trust upon the two-way CRAM-MD5 implementation. CRAM-MD5 is
35 subject to known plaintext attacks, and it should be considered
36 considerably less secure than PKI certificate-based authentication.
38 Appropriate autoconf macros have been added to detect and use OpenSSL
39 if enabled on the {\bf ./configure} line with {\bf \verb?--?enable-openssl}
41 \subsection*{TLS Configuration Directives}
42 \addcontentsline{toc}{section}{TLS Configuration Directives}
43 Additional configuration directives have been added to all the daemons
44 (Director, File daemon, and Storage daemon) as well as the various
45 different Console programs.
46 These new directives are defined as follows:
49 \item [TLS Enable = \lt{}yes|no\gt{}]
50 Enable TLS support. If TLS is not enabled, none of the other TLS directives
51 have any effect. In other words, even if you set {\bf TLS Require = yes}
52 you need to have TLS enabled or TLS will not be used.
54 \item [TLS Require = \lt{}yes|no\gt{}]
55 Require TLS connections. This directive is ignored unless {\bf TLS Enable}
56 is set to {\bf yes}. If TLS is not required, and TLS is enabled, then
57 Bacula will connect with other daemons either with or without TLS depending
58 on what the other daemon requests. If TLS is enabled and TLS is required,
59 then Bacula will refuse any connection that does not use TLS.
61 \item [TLS Certificate = \lt{}Directory\gt{}]
62 Path to a PEM encoded TLS certificate. It can be used as either a client
63 or server certificate. PEM stands for Privacy Enhanced Mail, but in
64 this context refers to how the certificates are encoded. It is used
65 because PEM files are base64 encoded and hence ASCII text based
66 rather than binary. They may also contain encrypted information.
68 \item [TLS Key = \lt{}Directory\gt{}]
69 Path to a PEM encoded TLS private key. It must correspond to the TLS
72 \item [TLS Verify Peer = \lt{}yes|no\gt{}]
73 Verify peer certificate. Instructs server to request and verify the
74 client's x509 certificate. Any client certificate signed by a known-CA
75 will be accepted unless the TLS Allowed CN configuration directive is used,
76 in which case the client certificate must correspond to the Allowed
77 Common Name specified. This directive is valid only for a server
78 and not in a client context.
80 \item [TLS Allowed CN = \lt{}string list\gt{}]
81 Common name attribute of allowed peer certificates. If this directive is
82 specified, all client certificates will be verified against this list.
83 This directive may be specified more than once. It is not valid in a client
86 \item [TLS CA Certificate File = \lt{}Filename\gt{}]
87 The full path and filename specifying a
88 PEM encoded TLS CA certificate(s). Multiple certificates are
89 permitted in the file. One of \emph{TLS CA Certificate File} or \emph{TLS
90 CA Certificate Dir} are required in a server context if \emph{TLS
91 Verify Peer} (see above) is also specified, and are always required in a client
94 \item [TLS CA Certificate Dir = \lt{}Directory\gt{}]
95 Full path to TLS CA certificate directory. In the current implementation,
96 certificates must be stored PEM encoded with OpenSSL-compatible hashes,
97 which is the subject name's hash and an extension of {bf .0}.
98 One of \emph{TLS CA Certificate File} or \emph{TLS CA Certificate Dir} are
99 required in a server context if \emph{TLS Verify Peer} is also specified,
100 and are always required in a client context.
102 \item [TLS DH File = \lt{}Directory\gt{}]
103 Path to PEM encoded Diffie-Hellman parameter file. If this directive is
104 specified, DH key exchange will be used for the ephemeral keying, allowing
105 for forward secrecy of communications. DH key exchange adds an additional
106 level of security because the key used for encryption/decryption by the
107 server and the client is computed on each end and thus is never passed over
108 the network if Diffie-Hellman key exchange is used. Even if DH key
109 exchange is not used, the encryption/decryption key is always passed
110 encrypted. This directive is only valid within a server context.
112 To generate the parameter file, you
116 openssl dhparam -out dh1024.pem -5 1024
121 \subsection*{Creating a Self-signed Certificate}
122 \index[general]{Creating a Self-signed Certificate }
123 \index[general]{Certificate!Creating a Self-signed }
124 \addcontentsline{toc}{subsection}{Creating a Self-signed Certificate}
126 You may create a self-signed certificate for use with the Bacula TLS that
127 will permit you to make it function, but will not allow certificate
128 validation. The .pem file containing both the certificate and the key
129 valid for 10 years can be made with the following:
133 openssl req -new -x509 -nodes -out bacula.pem -keyout bacula.pem -days 3650
137 The above script will ask you a number of questions. You may simply answer
138 each of them by entering a return, or if you wish you may enter your own data.
140 Note, however, that self-signed certificates will only work for the
141 outgoing end of connections. For example, in the case of the Director
142 making a connection to a File Daemon, the File Daemon may be configured to
143 allow self-signed certifictes, but the certificate used by the
144 Director must be signed by a certificate that is explicitly trusted on the
147 This is neccessary to prevent ``man in the middle'' attacks from tools such
148 as \elink{ettercap}{http://ettercap.sourceforge.net/}. Essentially, if the
149 Director does not verify that it is talking to a trusted remote endpoint,
150 it can be tricked into talking to a malicious 3rd party who is relaying and
151 capturing all traffic by presenting its own certificates to the Director
152 and File Daemons. The only way to prevent this is by using trusted
153 certificates, so that the man in the middle is incapable of spoofing the
154 connection using his own.
156 To get a trusted certificate (CA or Certificate Authority signed
157 certificate), you will either need to purchase certificates signed by a
158 commercial CA or find a friend that has setup his own CA or become a CA
159 yourself, and thus you can sign all your own certificates. The book
160 OpenSSL by John Viega, Matt Mesier \& Pravir Chandra from O'Reilly explains
161 how to do it, or you can read the documentation provided in the Open-source
162 PKI Book project at Source Forge: \elink{
163 http://ospkibook.sourceforge.net/docs/OSPKI-2.4.7/OSPKI-html/ospki-book.htm}
164 {http://ospkibook.sourceforge.net/docs/OSPKI-2.4.7/OSPKI-html/ospki-book.htm}.
165 Note, this link may change.
167 The program TinyCA has a very nice Graphical User Interface
168 that allows you to easily setup and maintain your own CA.
169 TinyCA can be found at
170 \elink{http://tinyca.sm-zone.net/}{http://tinyca.sm-zone.net/}.
173 \subsection*{Getting a CA Signed Certificate}
174 \index[general]{Certificate!Getting a CA Signed }
175 \index[general]{Getting a CA Signed Certificate }
176 \addcontentsline{toc}{subsection}{Getting a CA Signed Certificate}
178 The process of getting a certificate that is signed by a CA is quite a bit
179 more complicated. You can purchase one from quite a number of PKI vendors, but
180 that is not at all necessary for use with Bacula. To get a CA signed
181 certificate, you will either need to find a friend that has setup his own CA
182 or to become a CA yourself, and thus you can sign all your own certificates.
183 The book OpenSSL by John Viega, Matt Mesier \& Pravir Chandra from O'Reilly
184 explains how to do it, or you can read the documentation provided in the
185 Open-source PKI Book project at Source Forge:
187 http://ospkibook.sourceforge.net/docs/OSPKI-2.4.7/OSPKI-html/ospki-book.htm}
188 {http://ospkibook.sourceforge.net/docs/OSPKI-2.4.7/OSPKI-html/ospki-book.htm}.
189 Note, this link may change.
191 \subsection*{Example TLS Configuration Files}
192 \index[general]{Example!TLS Configuration Files}
193 \index[general]{TLS Configuration Files}
194 \addcontentsline{toc}{subsection}{Example TLS Configuration Files}
196 Landon has supplied us with the TLS portions of his configuration
197 files, which should help you setting up your own.
199 {\bf bacula-dir.conf}
202 Director { # define myself
207 TLS Verify Peer = yes
208 TLS Allowed CN = "bacula@backup1.example.com"
209 TLS Allowed CN = "administrator@example.com"
210 TLS CA Certificate File = /usr/local/etc/ssl/ca.pem
211 # This is a server certificate, used for incoming
212 # console connections.
213 TLS Certificate = /usr/local/etc/ssl/backup1/cert.pem
214 TLS Key = /usr/local/etc/ssl/backup1/key.pem
219 Address = backup1.example.com
222 TLS CA Certificate File = /usr/local/etc/ssl/ca.pem
223 # This is a client certificate, used by the director to
224 # connect to the storage daemon
225 TLS Certificate = /usr/local/etc/ssl/bacula@backup1/cert.pem
226 TLS Key = /usr/local/etc/ssl/bacula@backup1/key.pem
239 TLS Verify Peer = yes
240 # Allow only the Director to connect
241 TLS Allowed CN = "bacula@backup1.example.com"
242 TLS CA Certificate File = /usr/local/etc/ssl/ca.pem\
243 # This is a server certificate. It is used by connecting
244 # directors to verify the authenticity of this file daemon
245 TLS Certificate = /usr/local/etc/ssl/server1/cert.pem
246 TLS Key = /usr/local/etc/ssl/server1/key.pem
254 Storage { # definition of myself
257 # These TLS configuration options are used for incoming
258 # file daemon connections. Director TLS settings are handled
262 # Peer certificate is not required/requested -- peer validity
263 # is verified by the storage connection cookie provided to the
264 # File Daemon by the director.
266 TLS CA Certificate File = /usr/local/etc/ssl/ca.pem
267 # This is a server certificate. It is used by connecting
268 # file daemons to verify the authenticity of this storage daemon
269 TLS Certificate = /usr/local/etc/ssl/backup1/cert.pem
270 TLS Key = /usr/local/etc/ssl/backup1/key.pem
274 # List Directors who are permitted to contact Storage daemon
281 # Require the connecting director to provide a certificate
282 # with the matching CN.
283 TLS Verify Peer = yes
284 TLS Allowed CN = "bacula@backup1.example.com"
285 TLS CA Certificate File = /usr/local/etc/ssl/ca.pem
286 # This is a server certificate. It is used by the connecting
287 # director to verify the authenticity of this storage daemon
288 TLS Certificate = /usr/local/etc/ssl/backup1/cert.pem
289 TLS Key = /usr/local/etc/ssl/backup1/key.pem