1 imip-agent
2 ==========
3
4 This software implements an agent that can interpret e-mail messages
5 containing calendar information, maintain availability records for scheduling
6 participants, act on behalf of resources and other entities that need to
7 participate in scheduling, and support user interfaces for end-users whose
8 e-mail programs do not understand calendar data.
9
10 Getting Started
11 ===============
12
13 Eventually, this information should be incorporated into packages for various
14 operating system distributions, and these instructions should be largely
15 superfluous for most users.
16
17 System User and Filesystem Access
18 =================================
19
20 The data handled by imip-agent needs to be accessible to other software,
21 notably mail handling software and Web server software. Two approaches are
22 described here: LMTP delivery and local SMTP delivery.
23
24 LMTP Delivery
25 -------------
26
27 Here, imip-agent's programs run in a way that permits LMTP delivery (requiring
28 suitable local privileges to communicate with the mail storage solution)
29 whilst allowing the Web server to read data written by those programs.
30
31 A system group needs to be created for LMTP delivery and for certain users to
32 share resources:
33
34 addgroup lmtp
35
36 This group should be employed for LMTP delivery by systems like Cyrus and
37 Dovecot. See the section on configuring mail systems for delivery for more
38 information.
39
40 A system user needs to be created and to belong to certain groups in order to
41 deliver messages to mail stores and to publish resources on the Web:
42
43 useradd -d /var/lib/imip-agent -m -U -G lmtp,www-data -r imip-agent
44
45 Store details and published resources need to be accessible by the imip-agent
46 and www-data users. Thus, www-data also needs to belong to the lmtp group:
47
48 adduser www-data lmtp
49
50 Stored and published data is then initialised using the tools/init.sh script.
51 The script employs the setgid flag on the directories initialised for stored
52 and published data so that new files and directories have the appropriate
53 group associated with them.
54
55 It should be possible to omit all arguments to the init.sh script, but it is
56 also worth reading the help message:
57
58 tools/init.sh --help
59
60 Fixing ownership can be done using the tools/fix.sh script, in case some form
61 of modification has altered the ownership or membership of the created files
62 and directories.
63
64 Local SMTP Delivery
65 -------------------
66
67 Here, imip-agent's programs run in a way that permits local SMTP delivery
68 (which merely needs the ability to connect to a local network service) whilst
69 allowing the Web server to read data written by those programs.
70
71 A system user needs to be created and to belong to certain groups in order to
72 deliver messages to mail stores and to publish resources on the Web:
73
74 useradd -d /var/lib/imip-agent -m -U -G www-data -r imip-agent
75
76 Again, the tools/init.sh script will initialise directories for stored and
77 published data. The tools/config.sh script should be edited and the group
78 redefined as follows:
79
80 IMIP_AGENT_GROUP=www-data
81
82 If already installed, the /etc/imip-agent/config.sh script should be edited
83 instead.
84
85 Installing the Software
86 =======================
87
88 The tools/install.sh script should install the software in appropriate
89 locations. See the prerequisites below for other software that will be
90 required.
91
92 Configuring Other Software
93 ==========================
94
95 The conf directory contains subdirectories for different systems:
96
97 apache Apache 2 site configuration for publishing resources
98 cron Cron command scheduling for free/busy updates
99 exim Exim 4 routing and transport configuration
100 postfix Postfix routing and transport configuration
101
102 Either Exim or Postfix can be chosen as a mail system supporting the agent.
103
104 Configuring Mail Systems for the Agent
105 --------------------------------------
106
107 The essential aspect of mail system configuration involves mail transports and
108 the integration of agent programs into the mail processing pipeline. Thus, the
109 following files are of particular interest:
110
111 For Exim (in conf/exim)...
112
113 30_exim4-config_people Integration of agent programs
114 30_exim4-config_people_outgoing ...
115 30_exim4-config_resources ...
116
117 For Postfix (in conf/postfix)...
118
119 master.cf.items Integration of agent programs (for
120 inclusion in master.cf)
121 transport Configuration of agent transports
122 virtual Configuration of outgoing mail routing
123
124 Such files need adjusting for the deployment environment so that, for example,
125 the example.com domain would be replaced with a suitable value.
126
127 Where LMTP_SOCKET is employed, a suitable filesystem path is required; see
128 below for a discussion of LMTP and mail delivery.
129
130 If local SMTP delivery is being used, the conf/postfix/master.cf.items file
131 will need adjusting to use the appropriate system group.
132
133 Configuring Mail Systems for Mail Recipients
134 --------------------------------------------
135
136 The software should operate independently of the way mail recipients are
137 identified in any given mail system, and thus does not dictate things such as
138 routing or account querying. However, example configuration files are provided
139 that demonstrate the use of LDAP to identify mail recipients:
140
141 For Exim with LDAP (in conf/exim/ldap)...
142
143 010_exim4-config_people_outgoing Defines recipients and outgoing
144 mail routing
145 890_exim4-config_ldap_people ...
146 890_exim4-config_ldap_resources ...
147
148 For Postfix with LDAP (in conf/postfix/ldap)...
149
150 main.cf.example Defines recipients and outgoing
151 mail routing (for inclusion in
152 main.cf)
153
154 virtual_alias_maps_people.cf Defines recipients and outgoing
155 virtual_alias_maps_people_outgoing.cf mail routing
156 virtual_alias_maps_resources.cf ...
157
158 Since the use of LDAP can be somewhat challenging and also excessive in some
159 situations, examples of maintaining recipient information using a simpler
160 approach are provided:
161
162 For Exim without LDAP (in conf/exim/simple)...
163
164 010_exim4-config_people_outgoing Defines recipients and outgoing
165 mail routing
166 890_exim4-config_ldap_people ...
167 890_exim4-config_ldap_resources ...
168
169 virtual_people Defines recipient identities
170 virtual_resources belonging to known domains
171
172 virtual_domains Defines recipient domains
173 virtual_people_outgoing Defines sender addresses
174
175 For Postfix without LDAP (in conf/postfix/simple)...
176
177 main.cf.example Defines recipients and outgoing
178 mail routing (for inclusion in
179 main.cf)
180
181 virtual_alias_maps Defines recipients and outgoing
182 virtual_alias_maps_people_outgoing mail routing
183
184 In this simpler environment, recipient details must be manually edited in the
185 virtual alias map files, but this permits a very transparent way of
186 administering the system. To add support for delivery to local mailboxes, the
187 following alternative to virtual_alias_maps is provided as an example:
188
189 virtual_alias_maps_local Defines recipients and local users
190
191 Naturally, the above recipient identification configuration examples can be
192 disregarded in favour of other ways of defining mail recipients, subject to
193 the needs of any given environment.
194
195 LDAP Representations for Mail Recipients
196 ----------------------------------------
197
198 Relevant LDAP resources for structuring recipient information include the
199 following:
200
201 RFC 4524 Defines the mail attribute
202 http://tools.ietf.org/html/rfc4524
203
204 RFC 2798 Defines the inetOrgPerson object
205 http://tools.ietf.org/html/rfc2798 class
206
207 RFC 2739 Defines the calEntry object class
208 https://tools.ietf.org/html/rfc2739 supporting calFBURL
209
210 An additional draft RFC describes the mailRecipient object class:
211
212 https://tools.ietf.org/html/draft-lachman-ldap-mail-routing-03
213
214 Resource schemas for LDAP are not effectively standardised for the purposes of
215 this software. A useful object class, inetResource, was defined for the
216 iPlanet Calendar Server:
217
218 http://docs.oracle.com/cd/E19566-01/819-4437/6n6jckqrf/index.html#anocg
219 http://docs.oracle.com/cd/E19566-01/819-4437/6n6jckqr8/index.html
220
221 Although Kolab maintains notions of resources, they are tied up with the
222 notion of a shared folder and the kolabSharedFolder object class, although the
223 mailRecipient object class is employed by resources in Kolab.
224
225 Configuring Mail Systems for Mail Delivery
226 ------------------------------------------
227
228 The agent software assumes that delivery of mail to recipients may be
229 performed using LMTP to a suitable mailbox provider. This is largely beyond
230 the scope of this document, but systems such as Cyrus and Dovecot can be
231 configured to provide a Unix domain socket offering support for LMTP
232 connections.
233
234 For Cyrus, the following bug report is pertinent:
235
236 https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=494746
237
238 A permanent change in permissions on the Cyrus LMTP socket is therefore
239 required to make delivery available to the lmtp group:
240
241 dpkg-statoverride --force --update --add \
242 cyrus lmtp 750 /var/run/cyrus/socket
243
244 Configuring Cron for Free/Busy Updates
245 --------------------------------------
246
247 The periods occupied by recurring events are not expanded beyond a certain
248 window of time by imip-agent. As a consequence, free/busy collections need to
249 be progressively expanded over time to include periods occupied by such events
250 that were not previously recorded in those collections.
251
252 The conf/cron/cron.daily/imip-agent file contains commands that update
253 free/busy collections for all known users, and this should be copied to the
254 appropriate destination. For example:
255
256 cp conf/cron/cron.daily/imip-agent /etc/cron.daily/
257
258 Where frequency-specific directories are not supported by cron on a system, a
259 crontab entry of the appropriate format is required instead.
260
261 Configuring Web Servers for Free/Busy Publishing
262 ------------------------------------------------
263
264 Each user may request the publishing of their free/busy information by
265 configuring certain settings. The conf/apache/imip-agent.conf file provides a
266 configuration file for deployment with the Apache Web server software that
267 exposes a directory for Web publishing containing the published free/busy
268 information.
269
270 Access to free/busy information may not be moderated, but Web server
271 directives can be introduced to impose access controls. Mail programs that
272 wish to consult the free/busy information may have problems in dealing with
273 authentication mechanisms, however, and it may be regarded as acceptable in
274 certain environments to expose such information publicly or with
275 network-specific access constraints.
276
277 Configuring Web Servers for the Calendar Management Interface
278 -------------------------------------------------------------
279
280 A calendar management interface is provided to allow users to view and
281 interact with their calendars through the Web. The
282 conf/apache/imip-manager.conf file provides a configuration file for
283 deployment with the Apache Web server software that enables this interface.
284
285 Since such access to calendars should only be performed by identified
286 users, access controls are suggested in the configuration file.
287
288 Prerequisites
289 =============
290
291 Depending on the mail transport agent (MTA) chosen, the following packages are
292 required for this software to work on Debian systems:
293
294 Exim: exim4-daemon-heavy
295 Postfix: postfix postfix-ldap
296
297 The software itself requires the following packages:
298
299 Python: python
300 pytz: python-tz
301
302 The management Web interface requires the following packages:
303
304 Apache: apache2
305 Babel: python-babel
306
307 Although not necessarily within the scope of the deployment of this software,
308 the following mail storage solutions would be used to receive and hold
309 messages:
310
311 Cyrus: cyrus-imapd
312 Dovecot: dovecot-imapd dovecot-ldap dovecot-lmtpd