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  56 <a href="http://www.linuxsecurity.com/articles/documentation_article-9544.html">Securing Linux, Part 1: Introduction<br>
  57 </a></font><font face="Arial,Helvetica,Geneva,Swiss,SunSans-Regular" size="1">Jul 23<br>
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  72 <a href="http://www.linuxsecurity.com/articles/forums_article-9542.html">Linux Advisory Watch - July 23rd 2004<br>
  73 </a></font><font face="Arial,Helvetica,Geneva,Swiss,SunSans-Regular" size="1">Jul 23<br>
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  92   <tbody><tr><td><center><b><font face="Arial,Helvetica" size="+1">Today's Term</font></b></center>
  93       <font face="Arial,Helvetica" size="2"><a href="http://www.linuxsecurity.com/dictionary/dict-271.html">penetration</a>:
  94       <i>Successful, repeatable, unauthorized access to a protected system resource. (See: attack, violation.) ...</i>
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 112
 113       <font face="Arial,Helvetica" size="2"><a href="http://www.linuxsecurity.com/tips/tip-4.html">Monitoring Files with Special Permissions</a>:
 114       <br>Monitoring system files is crucial in maintaining host integrity.
 115
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 162                                                         <td height="15" align="right" nowrap="" width="100%"><font size="2" face="Arial,Helvetica,Geneva,Swiss,SunSans-Regular"><update_date>7/9/2004</update_date><update_time> 16:40</update_time></font></td>
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 169                                             <h3><article_title>Catching up with Wietse Venema, creator of Postfix and TCP Wrapper</article_title></h3>
 170                                             By <author_email><a href="mailto:duane@sukkha.info"></a></author_email><author><a href="mailto:duane@sukkha.info">Duane Dunston</a></author><br>
 171                                             <date>7/9/2004</date> <time>16:40</time><br><br>
 172                                             <b><summary>Wietse Venema is best known for the software <a href="ftp://ftp.porcupine.org/pub/security/index.html">TCP Wrapper</a>, which is still widely used today and is included with almost all unix systems.  Wietse is also the author of the <a href="http://www.postfix.org/">Postfix</a> mail system and the co-author of the very cool suite of utilities called <a href="http://www.porcupine.org/forensics/">The Coroner's Toolkit</a>
 173 or "TCT".  He is currently working at the Thomas J. Watson Research Center
 174 and he has gratiously agreed to allow us to catch up with him and and see
 175 what he's been up to lately.</summary></b><br><br>
 176                                             <description>Wietse Venema is best known for the software <a href="ftp://ftp.porcupine.org/pub/security/index.html">TCP Wrapper</a>, which is still widely used today and is included with almost all unix systems.  Wietse is also the author of the <a href="http://www.postfix.org/">Postfix</a> mail system and the co-author of the very cool suite of utilities called <a href="http://www.porcupine.org/forensics/">The Coroner's Toolkit</a>
 177 or "TCT".  He is currently working at the Thomas J. Watson Research Center
 178 and he has gratiously agreed to allow us to catch up with him and and see
 179 what he's been up to lately.  </description><p>
 180
 181 <b>Linuxsecurity.com:</b> Thanks for taking the time to interview with us.
 182 How you doing these days?  The most we hear from you is when Postfix
 183 is updated, the mailing lists, or something like that.  What are you up to?
 184
 185 </p><p>
 186
 187 <b>Wietse:</b> I have been finishing things, so that I can start work on new
 188 projects. After a major documentation rewrite for the Postfix mail
 189 system, I finished the manuscript for a book on computer forensic
 190 analysis with Dan Farmer.  When I finish something, I normally
 191 start reading everything that I can lay my hands on and then
 192 inspiration comes.
 193
 194 </p><p>
 195
 196 <b>Linuxsecurity.com:</b>  On your website you mentioned you go bike riding, weather permitting,
 197 how's the weather been where you are this year?
 198
 199 </p><p>
 200
 201 <b>Wietse:</b> It has been fairly typical here in southern New York state. We dig
 202 ourselves out from the snow a few times in January and February.
 203 Once the snow is gone in March, we spend quality time walking up
 204 a hill or riding a bike.  Many several former railroads are/were
 205 converted into trails, and riding them is fun. Unlike Europe, where
 206 I grew up, the roads in southern New York state are not really safe
 207 for riding a bicycle.
 208
 209 </p><p>
 210
 211 <b>Linuxsecurity.com:</b>  You have a suite of tools available on your website.  Any new
 212 ones coming out that address basic fundamental security practices that
 213 still aren't followed or are you going to add any new functionality to
 214 your existing programs?
 215
 216 </p><p>
 217
 218 <b>Wietse:</b> Some tools such as TCP WRAPPER are complete, and adding more features
 219 does not make them more useful. I would update them only so that
 220 they survive changes in operating systems, language compilers and/or
 221 network protocols.  Some tools such as SATAN have served their
 222 purpose, and now have historical value only.
 223
 224 </p><p>
 225
 226 <b>Linuxsecurity.com:</b> Does the continued success of TCP Wrapper surprise you?  If so,
 227 why is that?  What does TCP Wrapper have that makes it so valuable today.
 228
 229 </p><p>
 230
 231 Perhaps the biggest virtue is that tcp_wrappers works as expected.
 232 This means that not only the software is relatively error free, it
 233 is also possible for human beings to install, configure, and forget
 234 tcp_wrappers without getting into trouble.
 235
 236 </p><p>
 237
 238 It does not matter how well software is written when people can't
 239 figure out how to use it, or when it has sharp edges that make it
 240 unsafe to use.  Being safe and secure is hard enough with software
 241 like tcp_wrappers that spans only a few thousand lines of code.
 242
 243 </p><p>
 244
 245 With a 10 times larger system such as Postfix, even relatively
 246 error-free software contains a number of errors, and one has to
 247 build additional safety features into the architecture to prevent
 248 accidents from happening.  Just like elevators have safety brakes
 249 that prevent them from crashing into the basement, Postfix has
 250 safety brakes that most people never notice until they are needed.
 251
 252 </p><p>
 253
 254 <b>Linuxsecurity.com:</b>  Postfix is a really good Mail Transport Agent (MTA), I've been
 255 using it for a long time and I set it up for someone any chance I get.  Why
 256 did you decide to write a new MTA instead of scaling down an existing MTA? :-)
 257
 258 </p><p>
 259
 260 <b>Wietse:</b> Indeed, why would anyone spend so much time writing yet another
 261 UNIX-based mail system, when Sendmail and qmail already existed?
 262 When I was looking for a programming project, neither mail system
 263 was a desirable option for me, and enough people felt the same way.
 264
 265 </p><p>
 266
 267 Writing a new mail system from scratch was a change from previous
 268 projects. Normally I would retrofit security features almost
 269 invisibly, either by replacing an existing server such as portmap
 270 by a hardened version that was 100% compatible, or by adding a very
 271 thin layer such as tcp_wrappers. In the case of the Postfix mail
 272 system, there was no way that the changes could be made in an
 273 invisible manner.
 274
 275 </p><p>
 276
 277 <b>Linuxsecurity.com:</b>  What is your take on spam and the role the MTA plays in helping to
 278 prevent it?
 279
 280 </p><p>
 281
 282 <b>Wietse:</b> Stopping email that contains spam is not fundamentally different
 283 from stopping email that contains viruses.
 284
 285 </p><p>
 286
 287 In both cases, complex content analysis is better done outside the
 288 mail system. That allows people to choose the best mail system and
 289 the best spam/virus software for their environment.
 290
 291 </p><p>
 292
 293 And in both cases, a lot of spam or viral email comes from systems
 294 that have no business sending email directly across the Internet.
 295 These are often PCs on residential networks that have been compromised
 296 via some worm of virus, and that are under remote control by
 297 criminals that use those systems to send spam and/or to infect more
 298 systems.  These rogue systems can often be recognized by the way
 299 they implement the email protocols wrongly, if not by their
 300 residential IP address.
 301
 302 </p><p>
 303
 304 Blocking direct mail from rogue systems is best done by the ISP
 305 that hosts those systems, but that happens rarely. The next best
 306 solution is to block direct mail from rogue systems at the receiving
 307 end, and that is where Postfix can help.
 308
 309 </p><p>
 310
 311 <b>Linuxsecurity.com:</b>  In one article, I wrote about how attackers are still breaking
 312 into computer systems using well-known exploits.  Any ideas on how to help
 313 instill basic security practices in administrators and vendors?
 314
 315 </p><p>
 316
 317 <b>Wietse:</b> I think that learning by example is a good way to bring the point
 318 across.  This is what Dan Farmer and I attempted years ago with
 319 our white paper on improving the security of your system by breaking
 320 into it.
 321
 322 </p><p>
 323
 324 I have the same experience when explaining how to build more secure
 325 software. People just don't see that there is a problem until you
 326 can show good examples of software that does not do the things that
 327 it obviously was meant to do. Security problems happen when there
 328 is a mismatch between expected behavior and actual behavior.
 329
 330 </p><p>
 331
 332 <b>Linuxsecurity.com:</b>  How did you get into the forensics side of computers?
 333
 334 </p><p>
 335
 336 <b>Wietse:</b> The initial motivation for getting involved with computer forensics
 337 was to reconstruct computer break-ins, so that I could prevent them
 338 from happening again. An amazing amount of information can be found
 339 after an incident. As computers become more complex, humans have
 340 less control over when and where information is stored, and how
 341 that storage is recycled when information is discarded.
 342
 343 </p><p>
 344
 345 Because of this it is practically impossible to erase all information
 346 about an incident from a disk, without physically destroying the
 347 hardware.  Erasing all memory is difficult too, if you don't want
 348 to draw attention by crashing the system.  How much reconstruction
 349 is possible depends only on the amount of skill and effort you're
 350 willing to put in.
 351
 352 </p><p>
 353
 354 <b>Linuxsecurity.com:</b>  You and Dan Farmer still work on The Coroner's Toolkit (TCT).
 355 What research, seminars, or open source programs you working on in
 356 forensics?
 357
 358 </p><p>
 359
 360 <b>Wietse:</b> We just finished a manuscript for a book on computer forensic
 361 analysis that we hope will come out this year. In this book we
 362 write about things that we learned after we released the TCT. For
 363 some experiments we used the TCT, and for other measurements we
 364 wrote a few new tools.  When this book is published I will be happy
 365 to turn my attention to other projects.
 366
 367 </p><p>
 368
 369 <b>Linuxsecurity.com:</b>  We just wanted to catch up with you and see how things were
 370 going.  Can you please give us a final statement about keeping our systems secure?
 371 </p><p>
 372
 373 <b>Wietse:</b> You don't make a system secure by patching the holes - if the system
 374 wasn't built to be secure then it never will be.
 375
 376 </p><p>
 377
 378 <i>Linuxsecurity.com: Wietse provided this quote:</i>
 379
 380 </p><p>
 381
 382 "As long as there is support for ad hoc fixes and security
 383 packages for these inadequate designs and as long as the illusory
 384 results of penetration teams are accepted as demonstrations of
 385 computer system security, proper security will not be a reality."
 386
 387 </p><p>
 388
 389 Roger Schell et al., Preliminary notes on the Design of Secure
 390 Military Computer Systems, 1973. Archive of seminal security papers
 391 at http://seclab.cs.ucdavis.edu/projects/history/seminal.html
 392
 393 </p><p>
 394
 395 <b>Linuxsecurity.com:</b>  Okay one last thing, where were you and who drew that caricature
 396 on your website?
 397
 398 </p><p>
 399
 400 <b>Wietse:</b>  The caricature was drawn, by an artist whose name I do not know,
 401 at a conference dinner in 1997 when the Forum of Incident Response
 402 and Security Teams (www.first.org) met for its annual conference
 403 in Bristol, UK.  I have supported this organization for many years,
 404 and I even had the privilege of spending more than the maximal time
 405 as its chair.
 406
 407 </p><p>
 408 Duane Dunston is an Information Technology Specialist (Security) for the <a href="http://www.ncdc.noaa.gov/">National Climatic Data Center</a>. He was previously a contractor for <a href="http://www.stginc.com/">STG Inc.</a> for the same organization. He received his B.A. and M.S. degrees from <a href="http://www.pfeiffer.edu/">Pfeiffer University</a> and he has his GSEC certification from <a href="http://www.sans.org/">SANS</a>. Hey, <a href="http://msnbc.msn.com/id/4515786/">Ann Curry</a>!
 409
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