Chronophage's Blog

Tag: Software

Some Security is Better than None

by on Mar.29, 2012, under Security, UNIX 101

Having a laptop as your primary computer means that a whole chunk of your life is subject to walking off. Now, I’m no security expert, but here are a few things that I know to do in order, well, make me feel a little more secure.

First, my new computer is a MacBook. Mac OS X has a nice little feature that scrubs the files in trash as it deletes them. You can command click on the trash icon and choose “Secure Empty Trash” every time you empty it, or you can go “Finder Preferences”, click “Advanced” and check “Empty trash securely”

Next up, GPGtools. GPG is an open source implementation of PGP security. There are several small encryption related tools, but the killer one is the ability to sign and/or encrypt mail.

Next, I installed TrueCrypt. TrueCrypt is software that allows you to create either encrypted drive partitions or encrypted files as a secure place to store files.

Next, I installed Prey from This is free software that will help you track down your laptop should someone steal it. You can track three devices for free, including smart phones. I also enabled “Where’s my Mac?” and a cron/reverse-ssh/webserver scheme as other ways to recover my laptop should it grow legs and wander off.

For network access, I use OpenVPN to connect to my firewall, and an IPSEC tunnel to connect to my work firewall. Mike provided me a nifty VPNTracker “Player” that made configuring it a non-issue.

Just a few tips to keep my private life private…

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Postfix MySQL and You!

by on Oct.30, 2009, under Administration, E-Mail, News

Postfix is surprisingly flexible. When I initially set it up two years ago, I set it up to reference a database, but I had a flaw in my logic. Basically, Postfix had no idea if a domain was marked active or inactive in the database. All it knew was whether a domain was in the database or not. Postfix has a default query, that looks for key information. However, you can supercede it in your config files. So I simply commented out the old variables that it passed to the default query, and wrote a new one:

user = DB_USER
password = supersecretpassword
hosts =
dbname = DB_NAME
table = domain
#select_field = domain < -- old version, commented out
#where_field = domain <-- old version, commented out
#New Query:
query = SELECT domain FROM domain WHERE domain='%s' and backupmx = false and active = true

Yes, I have backupmx enabled, even though that’s a titanically bad idea, and I would never use it. Why is it a bad idea to fuction as a Backup MX server? Because spammers don’t play by the RFCs and often send spam to lower weighted MX records in an attempt to bypass spam protection.

But I never know what people may ask for in the future. ;)

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by on Sep.24, 2009, under Administration, News, Software

This is a live and learn moment. When I did my last update, I had a lot of old libraries hanging around. I thought that portupgrade would recompile all of my ports, but it didn’t. Most had been recompiled in the interim as I had been upgrading, but Apache, well, Apache upgrades are hardly for the weak. So, when I deleted a bunch of crud laying around. I broke SUEXEC. SUEXEC is what allows scripts to be executed under my various users’ home directories. Well, a recompile and reinstall, and things are working much much faster. Always fix your architecture kids.

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by on Aug.21, 2009, under News, Security

People are so curious nowadays… Today I’ve received one NMAP ping from Colorado State (I’m guessing since I recently downloaded NMAP) and one “Version” query from Or at least, I think I have. Oh well, no harm done.

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Ok, “ClueBringer” has some problems but it’s neat.

by on Aug.10, 2009, under E-Mail, News

Spam is fun. Watching spammers in action is even more fun. Via a friend, I have a very old domain that for which I handle mail. Since only one address is legitimate, it’s easy to use a wild card alias to catch and analyze spam. I implemented some Policies via Policyd2, aka “ClueBringer” (linux kids are cute, aren’t they?) Basically, I added a 20/hour recipient quota, and a 5/hour /24 based sender quota, hoping to bounce a few messages. It never happens. The bot network that sends these messages implements a simple, but effective interpolation scheme where the same address NEVER receives mail from the same ip address, and it always jumps /24s after 2 messages. It’s fascinating to watch.

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DNS and you!

by on Jul.31, 2009, under News, Security

Say what you want about Kaminsky. I mean, the man is crazy. However, being on call when your employer, a regional ISP, reboots both the primary and secondary DNS servers, makes you appreciate how important DNS is in the grand scheme of internet things. Granted, his attack is fairly novel, but yeah… I’m glad ISC makes updating BIND nice and easy.

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Chronophage E-mail Settings

by on May.18, 2009, under E-Mail, News

I host mail for a few friends and family. I use Postfix as my MTA with Dovecot as my SASL/LDA/POP/IMAP server. Users are authenticated via MySQL and PAM, so I can have local, and virtual accounts. To manage things, I user PostfixAdmin, with a few¬† tweeks to accomodate my virtual user’s file structure. Logins are either the full email address (virtual accounts) or the username.

I use a combination of SQLGrey and ClamAV and Maia(SpamAssassin frontend) for my anti-spam/anti-virus protection. SquirrelMail and RoundCube are both availible for webmail. Mutt and Alpine are installed on the server as well.

The Settings are as follows:

Main Settings:

The POP3/IMAP4  and SMTP server is

SMTP Authentication is ON

Ports are: 110/993* 143/995* and 25/587/465* for SMTP.

After switching LDA and SASL over to Dovecot, I have magnanimously set up Sieve scripting for my valuable users. And it works for both virtual and shell accounts.
Shell accounts can use either Squirrelmail, or upload Sieve scripts via the Sieve Thunderbird plugin or place them in your .sieve folder.
Virtual accounts will either have to use Squirrelmail or a program that can speak Sieve (standard port, 2000)
Sieve scripts DO count against your quota, so be careful Virtual Users.
This is LDA level filtering, so I can’t see what it’s doing via my logs, so watch your filters!

There are a lot of Sieve scripts out there, have fun!

Procmail and Maildrop are installed on the system, and can be used for shell users via a .forward file.

Webmail: for SquirrelMail for RoundCube

Postfix Admin redirects to

Shell users should be able to log in with their email address but passwords don’t sync with local passwords.

Send me an email to change passwords.

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