| [1] | 1 | <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
|
|---|
| 2 | <html>
|
|---|
| 3 | <head>
|
|---|
| 4 | <title>HOWTO client+server</title>
|
|---|
| 5 | <style type="text/css">
|
|---|
| 6 | <!--
|
|---|
| 7 |
|
|---|
| 8 | html { background: #eee; color: #000; }
|
|---|
| 9 |
|
|---|
| 10 | body { background: #eee; color: #000; margin: 0; padding: 0;}
|
|---|
| 11 |
|
|---|
| 12 | div.body {
|
|---|
| 13 | background: #fff; color: #000;
|
|---|
| 14 | margin: 0 1em 0 1em; padding: 1em;
|
|---|
| 15 | font-family: serif;
|
|---|
| 16 | font-size: 1em; line-height: 1.2em;
|
|---|
| 17 | border-width: 0 1px 0 1px;
|
|---|
| 18 | border-style: solid;
|
|---|
| 19 | border-color: #aaa;
|
|---|
| 20 | }
|
|---|
| 21 |
|
|---|
| 22 | div.block {
|
|---|
| 23 | background: #b6c5f2; color: #000;
|
|---|
| 24 | margin: 1em; padding: 0 1em 0 1em;
|
|---|
| 25 | border-width: 1px;
|
|---|
| 26 | border-style: solid;
|
|---|
| 27 | border-color: #2d4488;
|
|---|
| 28 | }
|
|---|
| 29 |
|
|---|
| 30 | div.warnblock {
|
|---|
| 31 | background: #b6c5f2; color: #000;
|
|---|
| 32 | margin: 1em; padding: 0 1em 0 1em;
|
|---|
| 33 | border-width: 1px;
|
|---|
| 34 | border-style: solid;
|
|---|
| 35 | border-color: #FF9900;
|
|---|
| 36 | }
|
|---|
| 37 |
|
|---|
| 38 | table {
|
|---|
| 39 | background: #F8F8F8; color: #000;
|
|---|
| 40 | margin: 1em;
|
|---|
| 41 | border-width: 0 0 0 1px;
|
|---|
| 42 | border-style: solid;
|
|---|
| 43 | border-color: #C0C0C0;
|
|---|
| 44 | }
|
|---|
| 45 |
|
|---|
| 46 | td {
|
|---|
| 47 | border-width: 0 1px 1px 0;
|
|---|
| 48 | border-style: solid;
|
|---|
| 49 | border-color: #C0C0C0;
|
|---|
| 50 | }
|
|---|
| 51 |
|
|---|
| 52 | th {
|
|---|
| 53 | background: #F8F8FF;
|
|---|
| 54 | border-width: 1px 1px 2px 0;
|
|---|
| 55 | border-style: solid;
|
|---|
| 56 | border-color: #C0C0C0;
|
|---|
| 57 | }
|
|---|
| 58 |
|
|---|
| 59 |
|
|---|
| 60 | /* body text, headings, and rules */
|
|---|
| 61 |
|
|---|
| 62 | p { margin: 0; text-indent: 0em; margin: 0 0 0.5em 0 }
|
|---|
| 63 |
|
|---|
| 64 | h1, h2, h3, h4, h5, h6 {
|
|---|
| 65 | color: #206020; background: transparent;
|
|---|
| 66 | font-family: Optima, Arial, Helvetica, sans-serif;
|
|---|
| 67 | font-weight: normal;
|
|---|
| 68 | }
|
|---|
| 69 |
|
|---|
| 70 | h1 { font-size: 1.69em; margin: 1.4em 0 0.4em 0; }
|
|---|
| 71 | h2 { font-size: 1.44em; margin: 1.4em 0 0.4em 0; }
|
|---|
| 72 | h3 { font-size: 1.21em; margin: 1.4em 0 0.4em 0; }
|
|---|
| 73 | h4 { font-size: 1.00em; margin: 1.4em 0 0.4em 0; }
|
|---|
| 74 | h5 { font-size: 0.81em; margin: 1.4em 0 0.4em 0; }
|
|---|
| 75 | h6 { font-size: 0.64em; margin: 1.4em 0 0.4em 0; }
|
|---|
| 76 |
|
|---|
| 77 | hr {
|
|---|
| 78 | color: transparent; background: transparent;
|
|---|
| 79 | height: 0px; margin: 0.6em 0;
|
|---|
| 80 | border-width: 1px ;
|
|---|
| 81 | border-style: solid;
|
|---|
| 82 | border-color: #999;
|
|---|
| 83 | }
|
|---|
| 84 |
|
|---|
| 85 | /* bulleted lists and definition lists */
|
|---|
| 86 |
|
|---|
| 87 | ul { margin: 0 1em 0.6em 2em; padding: 0; }
|
|---|
| 88 | li { margin: 0.4em 0 0 0; }
|
|---|
| 89 |
|
|---|
| 90 | dl { margin: 0.6em 1em 0.6em 2em; }
|
|---|
| 91 | dt { color: #285577; }
|
|---|
| 92 |
|
|---|
| 93 | tt { color: #602020; }
|
|---|
| 94 |
|
|---|
| 95 | /* links */
|
|---|
| 96 |
|
|---|
| 97 | a.link {
|
|---|
| 98 | color: #33c; background: transparent;
|
|---|
| 99 | text-decoration: none;
|
|---|
| 100 | }
|
|---|
| 101 |
|
|---|
| 102 | a:hover {
|
|---|
| 103 | color: #000; background: transparent;
|
|---|
| 104 | }
|
|---|
| 105 |
|
|---|
| 106 | body > a {
|
|---|
| 107 | font-family: Optima, Arial, Helvetica, sans-serif;
|
|---|
| 108 | font-size: 0.81em;
|
|---|
| 109 | }
|
|---|
| 110 |
|
|---|
| 111 | h1, h2, h3, h4, h5, h6 {
|
|---|
| 112 | color: #2d5588; background: transparent;
|
|---|
| 113 | font-family: Optima, Arial, Helvetica, sans-serif;
|
|---|
| 114 | font-weight: normal;
|
|---|
| 115 | }
|
|---|
| 116 |
|
|---|
| 117 | -->
|
|---|
| 118 | </style></head>
|
|---|
| 119 |
|
|---|
| 120 | <body>
|
|---|
| 121 | <div class="body">
|
|---|
| 122 | <p style="text-align: center; background: #ccc; border: 1px solid #2d5588;"><a
|
|---|
| 123 | style="text-decoration: none;"
|
|---|
| 124 | href="http://www.la-samhna.de/samhain/">samhain file integrity
|
|---|
| 125 | scanner</a> | <a style="text-decoration: none;"
|
|---|
| 126 | href="http://www.la-samhna.de/samhain/s_documentation.html">online
|
|---|
| 127 | documentation</a></p>
|
|---|
| 128 | <br><center>
|
|---|
| 129 | <h1>Setting up a client/server samhain system</h1>
|
|---|
| 130 | </center>
|
|---|
| 131 | <br>
|
|---|
| 132 | <hr>
|
|---|
| 133 | <p>
|
|---|
| 134 | This document aims to explain how to set up a client/server
|
|---|
| 135 | samhain system, where the client (samhain) runs on one machine to be
|
|---|
| 136 | monitored, and sends reports via TCP/IP to a remote server (yule).
|
|---|
| 137 | </p>
|
|---|
| 138 | <p>
|
|---|
| 139 | <b>Please note:</b> the server (yule) does not perform any filesystem and/or
|
|---|
| 140 | kernel checks. If you want to perform such checks on the log server host,
|
|---|
| 141 | you need to run a samhain client on this host as well.
|
|---|
| 142 | </p>
|
|---|
| 143 | <p>
|
|---|
| 144 | Client and server are
|
|---|
| 145 | <b>distict applications</b>, and must be
|
|---|
| [553] | 146 | built separately. By default, installation names and paths (e.g.
|
|---|
| [1] | 147 | the configuration file) are
|
|---|
| 148 | different. Do not blame us if you abuse './configure' options to
|
|---|
| 149 | cause name clashes, if you install both on the same host.
|
|---|
| 150 | </p>
|
|---|
| 151 |
|
|---|
| 152 | <h2>Introduction</h2>
|
|---|
| 153 | <p>
|
|---|
| 154 | Samhain can be compiled for remote logging to a central server via a
|
|---|
| 155 | secure (AES-encrypted, signed, and authenticated) TCP/IP connection.
|
|---|
| 156 | </p><p>
|
|---|
| 157 | In addition, both the client configuration file and the file signature
|
|---|
| 158 | database can be stored on the server. The client will then pull them from
|
|---|
| 159 | the server upon startup.
|
|---|
| 160 | </p><p>
|
|---|
| 161 | This requires three basic steps:
|
|---|
| 162 | </p>
|
|---|
| 163 | <ol>
|
|---|
| 164 | <li>
|
|---|
| 165 | compile and install server and client,
|
|---|
| 166 | </li>
|
|---|
| 167 | <li>
|
|---|
| 168 | establish trust between client and server, and
|
|---|
| 169 | </li>
|
|---|
| 170 | <li>
|
|---|
| 171 | enable remote logging in the client's configuration file.
|
|---|
| 172 | </li>
|
|---|
| 173 | </ol>
|
|---|
| 174 |
|
|---|
| 175 |
|
|---|
| 176 | <h2>Compiling</h2>
|
|---|
| 177 |
|
|---|
| 178 | <h3>The server - yule</h3>
|
|---|
| 179 |
|
|---|
| 180 | <p>
|
|---|
| 181 | <b>Note: </b> the server can be started with root privileges (e.g. to use
|
|---|
| 182 | a privileged port < 1024), but it will always
|
|---|
| 183 | drop root privileges irrevocably
|
|---|
| 184 | before accepting any connections, and run as a non-root user. This user
|
|---|
| 185 | can be specified explicitely with the <i>configure</i>
|
|---|
| 186 | option <tt>--enable-identity=USER</tt>. The default is
|
|---|
| 187 | the first existing user
|
|---|
| 188 | out of the list <i>yule, daemon, nobody</i>.
|
|---|
| 189 | </p>
|
|---|
| 190 |
|
|---|
| 191 | <pre>
|
|---|
| 192 |
|
|---|
| 193 | bash$ ./configure --enable-network=server
|
|---|
| 194 | bash$ make
|
|---|
| 195 | bash$ make install
|
|---|
| 196 |
|
|---|
| 197 | </pre>
|
|---|
| 198 |
|
|---|
| 199 | <h3>The client - samhain</h3>
|
|---|
| 200 |
|
|---|
| 201 |
|
|---|
| 202 | <ul>
|
|---|
| 203 | <li>
|
|---|
| 204 | <p>
|
|---|
| 205 | If you just want remote logging:
|
|---|
| 206 | </p><p>
|
|---|
| 207 | <tt> ./configure --enable-network=client
|
|---|
| 208 | --with-logserver=server.example.com</tt>
|
|---|
| 209 | </p>
|
|---|
| 210 | </li>
|
|---|
| 211 | <li>
|
|---|
| 212 | <p>
|
|---|
| 213 | If you want configuration and database files on the server:
|
|---|
| 214 | </p><p>
|
|---|
| 215 | <tt> ./configure --enable-network=client
|
|---|
| 216 | --with-logserver=server.example.com \<br />
|
|---|
| 217 | --with-config-file=REQ_FROM_SERVER/etc/samhainrc \<br />
|
|---|
| 218 | --with-data-file=REQ_FROM_SERVER/var/lib/samhain/samhain_file</tt>
|
|---|
| 219 | </p>
|
|---|
| 220 | </li>
|
|---|
| 221 | </ul>
|
|---|
| 222 | <p>
|
|---|
| 223 | The path after the keyword <tt>REQ_FROM_SERVER</tt> has the following meaning:
|
|---|
| 224 | <ul>
|
|---|
| 225 | <li>for the configuration file:
|
|---|
| 226 | <ul>
|
|---|
| 227 | <li> if <i>initializing</i>, and the connection to the server
|
|---|
| 228 | fails, samhain will fall back on the local file (if given);
|
|---|
| 229 | </li>
|
|---|
| 230 | <li> if in <i>check mode</i>, it is <i>ignored</i>. Samhain will
|
|---|
| 231 | abort if the connection to the server fails.
|
|---|
| 232 | </li>
|
|---|
| 233 | </ul>
|
|---|
| 234 | Thus, the local path allows you to initialize the database from a local
|
|---|
| 235 | configuration file before the client is known to the server.
|
|---|
| 236 | </li>
|
|---|
| 237 | <li>for the database file:
|
|---|
| 238 | <ul>
|
|---|
| 239 | <li> if <i>initializing</i>, the database is written to the local file;
|
|---|
| 240 | </li>
|
|---|
| 241 | <li> if in <i>check mode</i>, the local path is <i>ignored</i>. Samhain will
|
|---|
| 242 | abort if the connection to the server fails.
|
|---|
| 243 | </li>
|
|---|
| 244 | </ul>
|
|---|
| 245 | Thus, <i>init</i> (or <i>update</i>) always requires a local file that
|
|---|
| 246 | must be uploaded to the server thereafter. <b>Note</b> that if you
|
|---|
| 247 | use the <b>Beltane</b> web-based frontend, database updates can be performed
|
|---|
| 248 | on the server without ever running an <i>update</i> on the client.
|
|---|
| 249 | </li>
|
|---|
| 250 | </ul>
|
|---|
| 251 |
|
|---|
| 252 | <h2>Establishing trust between client and server</h2>
|
|---|
| 253 |
|
|---|
| 254 | <p>
|
|---|
| 255 | By default, samhain uses the SRP (Secure Remote Password) protocol,
|
|---|
| 256 | with a password that is <i>embedded in the client binary</i>, and a
|
|---|
| 257 | corresponding verifier that is in the <i>server configuration file</i>.
|
|---|
| 258 | </p>
|
|---|
| 259 |
|
|---|
| 260 | <h3>Embedding the password in the client, and register it with the server</h3>
|
|---|
| 261 |
|
|---|
| 262 | <p>
|
|---|
| 263 | To embed the password in the binary, there is a dummy password compiled
|
|---|
| 264 | in as placeholder, and a utility <i>samhain_setpwd</i> is provided that
|
|---|
| 265 | </p>
|
|---|
| 266 |
|
|---|
| 267 | <ol>
|
|---|
| 268 | <li>
|
|---|
| 269 | takes a password as input,
|
|---|
| 270 | </li>
|
|---|
| 271 | <li>
|
|---|
| 272 | searches the original binary for the
|
|---|
| 273 | correct place (i.e. the placeholder), and
|
|---|
| 274 | </li>
|
|---|
| 275 | <li>
|
|---|
| 276 | writes a copy of the original binary, with the placeholder replaced
|
|---|
| 277 | by the password. The original is left untouched. The copy cannot
|
|---|
| 278 | be changed to another password anymore.
|
|---|
| 279 | </li>
|
|---|
| 280 | </ol>
|
|---|
| 281 |
|
|---|
| 282 |
|
|---|
| 283 | <p>
|
|---|
| 284 | For convenience, the server has functions to
|
|---|
| 285 | </p>
|
|---|
| 286 |
|
|---|
| 287 | <ul>
|
|---|
| 288 | <li>
|
|---|
| 289 | <p>
|
|---|
| 290 | generate a random password in the correct format:
|
|---|
| 291 | </p><p>
|
|---|
| 292 | <tt> sh$ yule -G</tt>
|
|---|
| 293 | </p>
|
|---|
| 294 | </li>
|
|---|
| 295 | <li>
|
|---|
| 296 | <p>
|
|---|
| 297 | and generate a corresponding entry for the
|
|---|
| 298 | server configuration file:
|
|---|
| 299 | </p><p>
|
|---|
| 300 | <tt> sh$ yule -P PASSWORD</tt>.
|
|---|
| 301 | <p>
|
|---|
| 302 | </li>
|
|---|
| 303 | <li>
|
|---|
| 304 | The generated entry has a string <tt>'HOSTNAME'</tt> that you should
|
|---|
| 305 | replace with the fully qualified name of the client. This entry must
|
|---|
| 306 | then be placed in the <tt>[Clients]</tt> section of the yule configuration
|
|---|
| 307 | file (e.g. <tt>/etc/yulerc</tt>).
|
|---|
| 308 | </li>
|
|---|
| 309 | <li>
|
|---|
| 310 | Finally, you need to tell yule to reload the configuration (send SIGHUP,
|
|---|
| 311 | or use <tt>/etc/init.d/yule reload</tt>).
|
|---|
| 312 | </li>
|
|---|
| 313 | </ul>
|
|---|
| 314 |
|
|---|
| 315 |
|
|---|
| 316 | <h3>Example</h3>
|
|---|
| 317 |
|
|---|
| 318 | <pre style="background-color:#DDDDDD; color:#000000">
|
|---|
| 319 |
|
|---|
| 320 | rainer$ ./samhain_setpwd
|
|---|
| 321 |
|
|---|
| 322 | Usage: samhain_setpwd <filename> <suffix> <new_password>
|
|---|
| 323 |
|
|---|
| 324 | This program is a utility that will:
|
|---|
| 325 | - search in the binary executable <filename> for samhain's
|
|---|
| 326 | compiled-in default password,
|
|---|
| 327 | - change it to <new_password>,
|
|---|
| 328 | - and output the modified binary to <filename>.<suffix>
|
|---|
| 329 |
|
|---|
| 330 | To allow for non-printable chars, <new_password> must be
|
|---|
| 331 | a 16-digit hexadecimal number (only 0-9,A-F allowed in input),
|
|---|
| 332 | thus corresponding to an 8-byte password.
|
|---|
| 333 |
|
|---|
| 334 | Example: 'samhain_setpwd samhain new 4142434445464748'
|
|---|
| 335 | takes the file 'samhain', sets the password to 'ABCDEFGH'
|
|---|
| 336 | ('A' = 41 hex, 'B' = 42 hex, ...) and outputs the result
|
|---|
| 337 | to 'samhain.new'.
|
|---|
| 338 |
|
|---|
| 339 | rainer$ yule -G
|
|---|
| 340 | 5B5CDF18CE8D66A3
|
|---|
| 341 |
|
|---|
| 342 | rainer$ ./samhain_setpwd samhain new 5B5CDF18CE8D66A3
|
|---|
| 343 | INFO old password found
|
|---|
| 344 | INFO replaced: f7c312aaaa12c3f7 by: 5b5cdf18ce8d66a3
|
|---|
| 345 | INFO finished
|
|---|
| 346 |
|
|---|
| 347 | rainer$ scp ./samhain.new root@client.example.com:/usr/local/sbin/samhain
|
|---|
| 348 | samhain 100% |********************************| 592 KB 00:00
|
|---|
| 349 |
|
|---|
| 350 | rainer$ yule -P 5B5CDF18CE8D66A3
|
|---|
| 351 | Client=HOSTNAME@8A542F99C3514499@744C3A3EE8323470D9DAD42E2485BD0B138F6B4116E964\
|
|---|
| 352 | A9991A0B0D221E1AADE5800968804B99B494C39E7B9DD5710D18F1E6703D1DB6D6393295E05DF6A\
|
|---|
| 353 | 6AA8D10BB4A21D7D9DC4901D444500D4EA358C1B44A3E3D44ACEC645F938F790A11AB0D03586143\
|
|---|
| 354 | 977E2BCE3A2D689445AC89134B409E68F34B0DE8BD8242ADD7C0
|
|---|
| 355 |
|
|---|
| 356 | rainer$ yule -P 5B5CDF18CE8D66A3 | sed s%HOSTNAME%client.example.com% >> /etc/yulerc
|
|---|
| 357 |
|
|---|
| 358 | rainer$ tail -2 /etc/yulerc
|
|---|
| 359 | [Clients]
|
|---|
| 360 | Client=client.example.com@8A542F99C3514499@744C3A3EE8323470D9DAD42E2485BD0B138F
|
|---|
| 361 | 6B4116E964A9991A0B0D221E1AADE5800968804B99B494C39E7B9DD5710D18F1E6703D1DB6D6393
|
|---|
| 362 | 295E05DF6A6AA8D10BB4A21D7D9DC4901D444500D4EA358C1B44A3E3D44ACEC645F938F790A11AB
|
|---|
| 363 | 0D03586143977E2BCE3A2D689445AC89134B409E68F34B0DE8BD8242ADD7C0
|
|---|
| 364 |
|
|---|
| 365 | rainer$ /etc/init.d/yule reload
|
|---|
| 366 |
|
|---|
| 367 | </pre>
|
|---|
| 368 |
|
|---|
| 369 | <p>
|
|---|
| 370 | <b>Note 1:</b> the verifier <tt>Client=client.example.com@.....</tt> must be
|
|---|
| 371 | in the <b>[Clients]</b> section of the server configuration file. It is
|
|---|
| 372 | convenient if this is the last section in the config file, because then
|
|---|
| 373 | you can just concatenate the output of <tt>yule -P PASSWORD</tt> to the
|
|---|
| 374 | configuration file. This allows for better automatisation with a simple
|
|---|
| 375 | script.
|
|---|
| 376 | </p>
|
|---|
| 377 | <p>
|
|---|
| 378 | <b>Note 2:</b> samhain comes with a <b>deploy system</b> that handles
|
|---|
| 379 | the deployment of clients, including password embedding and server
|
|---|
| 380 | configuration, in a semi-automatic way.
|
|---|
| 381 | This deploy system is tested and used in a production system
|
|---|
| 382 | of more than 50 machines, and described in detail in Chapt. 10 of the MANUAL.
|
|---|
| 383 | </p>
|
|---|
| 384 |
|
|---|
| 385 | <h2>Enabling remote logging</h2>
|
|---|
| 386 | <p>
|
|---|
| 387 | Samhain has multiple independent logging facilities (such as a local logfile,
|
|---|
| 388 | syslog, e-mail, TCP/IP, etc.) that can be used
|
|---|
| 389 | in parallel. You therefore have to specify in the client's configuration
|
|---|
| 390 | file, <b>which logging facility</b> you want to use.
|
|---|
| 391 | </p>
|
|---|
| 392 | <p>
|
|---|
| 393 | Selecting logging facilities is done by setting appropriate <b>thresholds</b>
|
|---|
| 394 | in the <b>[Log]</b> section of the configuration file: each
|
|---|
| 395 | message with a <b>priority</b> exceeding
|
|---|
| 396 | the threshold will be logged via the respective facility. Setting
|
|---|
| 397 | the threshold to <i>none</i> will disable a facility. For details,
|
|---|
| 398 | refer to Chapt. 4 in the MANUAL.
|
|---|
| 399 | </p>
|
|---|
| 400 | <h3>Example</h3>
|
|---|
| 401 | <p>
|
|---|
| 402 | To enable remote logging to the server for all messages of
|
|---|
| 403 | priority <i>error</i> or higher, use the following directive in the
|
|---|
| 404 | client configuration file:
|
|---|
| 405 | </p>
|
|---|
| 406 | <pre style="background-color:#DDDDDD; color:#000000">
|
|---|
| 407 |
|
|---|
| 408 | [Log]
|
|---|
| 409 | ExportSeverity=err
|
|---|
| 410 |
|
|---|
| 411 | </pre>
|
|---|
| 412 |
|
|---|
| 413 |
|
|---|
| 414 | <h2>Databases and config files on the server</h2>
|
|---|
| 415 |
|
|---|
| 416 | <p>
|
|---|
| 417 | The client does <i>not</i> tell the server the path to the requested
|
|---|
| 418 | file - it just requests a config or a database file. It's entirely the
|
|---|
| 419 | responsibility of the server to locate the correct file and send it.
|
|---|
| 420 | </p>
|
|---|
| 421 | <p>
|
|---|
| 422 | The server has a <i>data directory</i>, which by default would be
|
|---|
| 423 | <tt>/var/lib/yule</tt>, but depends on your compile options.
|
|---|
| 424 | </p>
|
|---|
| 425 | <p>
|
|---|
| 426 | Config files and baseline databases for clients must be located
|
|---|
| 427 | in this directory, and they must be named as follows:
|
|---|
| 428 | </p>
|
|---|
| 429 | <p>
|
|---|
| 430 | Configuration files: <tt>rc.</tt><i>client.mydomain.tld</i> or
|
|---|
| 431 | simply <tt>rc</tt>
|
|---|
| 432 | (this can be used as a catchall file).
|
|---|
| 433 | </p>
|
|---|
| 434 | <p>
|
|---|
| 435 | Database files: <tt>file.</tt><i>client.mydomain.tld</i> or
|
|---|
| 436 | simply <tt>file</tt>
|
|---|
| 437 | (this can be used as a catchall file).
|
|---|
| 438 | </p>
|
|---|
| 439 | </div>
|
|---|
| 440 | </body>
|
|---|
| 441 | </html>
|
|---|
