oinkmaster - update Snort signatures

oinkmaster -o outdir [options]

Oinkmaster is simple tool that helps you keep your Snort rules current with little or no user interaction. It downloads a tarball containing the new rules and can then enable, disable or even make arbitrary modifications to specified rules before updating your local rules files. It will also tell you the exact changes from your previous rules.

The only required argument to Oinkmaster is -o outdir where outdir is the directory to put the new rules files in. This should be where you keep your rules locally. The downloaded files will be compared to the ones in here before possibly overwriting them.

Optional arguments:

"-b If the rules have been modified, a tarball of your old rules will be put in dir before overwriting them with the new files. No backup is done if no file has changed or if Oinkmaster is running in careful mode.

"-c Run in careful mode. This means that Oinkmaster will only check for updates and print them, but not update anything.

"-C Use this configuration file instead of the default. If not specified, oinkmaster.conf will be looked for in /etc/ and then /usr/local/etc/. You can specify multiple -C cfg to load multiple configuration files. They will be loaded in order of appearance on the command line. If an option is redefined, it overrides the previous value (except for the "url" option, as you are allowed to specify multiple URLs).

"-e Enable rules that are disabled by default in the downloaded rules archive by removing all the leading "#" from them. If there are any disabled rules in the archive, they will stay that way unless you use this option. Remember that they are disabled for a reason (they may not even work), so use this option with care.

"-h Show valid command line arguments with short descriptions

"-i Enable interactive mode. You will be asked to approve the changes (if any) before updating anything.

"-m Minimize/simplify the diff when printing result for modified rules by removing common leading and trailing parts of the old and new rule so it's easier to see the actual change. A few characters to the left and to the right of the change are also printed so you get some context. The rev keyword is ignored when the comparison and removal of common parts is performed because it would often make the whole idea fail. (If you feel it's important to be able to verify that the rev number has increased when a rule has been updated, do not use the minimized diff mode.)

Normally when a rule has changed the entire old and new versions are printed, but the actual change between them can be hard to see if the rules are long, complex and many.

The normal output could look like this:

       Old: alert tcp any any -> any 22 (msg: "foo"; flags: A+; rev:1;)
       New: alert tcp any any -> any 123 (msg: "foo"; flags: A+; rev:2;)

When using -m it would instead look something like:

       Old: ...any any -> any 22 (msg: "foo";...
       New: ...any any -> any 123 (msg: "foo";...

"-q Run in quiet mode. Nothing is printed unless there are changes in the rules or if there are errors or warnings.

"-Q Run in super-quiet mode. This is the same as -q but even more quiet when printing the results (the "None." stuff is not printed). It will also suppress some other warning messages such as those for duplicate SIDs and non-matching modifysid expressions.

"-r Check for rules files that exist in the output directory but not in the downloaded rules archive, i.e. files that may have been removed from the distribution archive.

"-s Leave out details when printing results (aka bmc mode). This means that the entire added / removed / modified rules will not be printed, just their SID and msg string, plus the filename. Non-rule changes are printed as usual. This output mode could be useful for example if you send the output by email to people who don't really care about the details of the rules, just the fact that they have been updated. Example output when running with -s

       [+++]          Added rules:          [+++]

1607 - WEB-CGI HyperSeek hsx.cgi access (web-cgi.rules) 1775 - MYSQL root login attempt (mysql.rules)

[///] Modified active rules: [///]

302 - EXPLOIT Redhat 7.0 lprd overflow (exploit.rules) 304 - EXPLOIT SCO calserver overflow (exploit.rules) 305 - EXPLOIT delegate proxy overflow (exploit.rules) 306 - EXPLOIT VQServer admin (exploit.rules)

"-T Check the configuration file(s) for fatal errors and then exit. Possible warning messages are printed as well.

"-u Download the rules archive from url instead of the location specified in the configuration file. It must start with file://, ftp://, http://, https:// or scp:// and end with ".tar.gz" or ".tgz". The file must be a gzipped tarball containing a directory named "rules", holding all the rules files. For the official Snort rules, the URL to use depends on the version of Snort you run and it might also require registration. Visit the rules download section at the Snort web site to find the right URL and more information. Remember to update the URL when upgrading to a new major version of Snort.

You may specify multiple -u url to grab multiple rules archives from different locations. All rules files in the archives will be put in the same output directory so if the same filename exists in multiple archives, Oinkmaster will print an error message and exit. That's why it's usually recommended to instead run Oinkmaster once for each URL and use separate output directories. If -u url is specified, it overrides any URLs specified in the configuration file(s). Note that if multiple URLs are specified and one of them is broken, Oinkmaster will exit immediately without further processing. This can be good or bad, depending on the situation.

"-U Variables (i.e. "var foo bar" lines) that exist in downloaded snort.conf but not in file will be added to this one, right after any other variables it may contain. Modified existing variables are not merged, only new ones. file is normally your production copy of snort.conf (which should not be a file that is updated by Oinkmaster the normal way). This feature is to prevent Snort from breaking in case there are new variables added in the downloaded rules, as Snort can not start if the rules use variables that aren't defined anywhere. If you download from multiple URLs, Oinkmaster will look for a snort.conf in each downloaded rules archive.

"-v Run in verbose mode.

"-V Show version and exit.

Download rules archive from default location specified in oinkmaster.conf and put the new rules in /etc/rules/:

    oinkmaster -o /etc/rules 

Grab rules archive from local filesystem and do not print anything unless it contains updated rules:

    oinkmaster -u file:///tmp/rules.tar.gz -o /etc/rules -q 

Download rules archive from default location, make backup of old rules if there were updates, and send output by e-mail. (Note however that if you plan on distributing files with Oinkmaster that could be considered sensitive, such as Snort configuration files containing database passwords, you should of course not send the output by e-mail without first encrypting the content.)

    oinkmaster -o /etc/snort/rules -b /etc/snort/backup 2>&1 | \
    mail -s "subject" user@example.com

Load settings from two different files, use scp to download rules archive from a remote host where you have put the rules archive, merge variables from downloaded snort.conf, and send results by e-mail only if anything changed or if there were any error messages. It assumes that the "mktemp" command is available on the system:

    TMP=`mktemp /tmp/oinkmaster.XXXXXX` && \
    (oinkmaster -C /etc/oinkmaster-global.conf \
    -C /etc/oinkmaster-sensor.conf -o /etc/rules \
    -U /etc/snort.conf \
    -u scp://user@example.com:/home/user/rules.tar.gz \
    > $TMP 2>&1; if [ -s $TMP ]; then mail -s "subject" \
    you@example.com < $TMP; fi; rm $TMP) 

/etc/oinkmaster.conf

/usr/local/etc/oinkmaster.conf

If you find a bug, report it by e-mail to the author. Always include as much information as possible.

The initial version was released in early 2001 under the name arachnids_upd. It worked only with the ArachNIDS Snort rules, but as times changed, it was rewritten to work with the official Snort rules and the new name became Oinkmaster.

Andreas Ostling <andreaso@it.su.se>

The online documentation at http://oinkmaster.sf.net/ contains more information.