SNORT: email alert

Sumber: https://www.safaribooksonline.com/library/view/snort-cookbook/0596007914/ch02s16.html

Since I had to piece this together from many sites, I'm adding this here in the interest of completeness:

If you need a more robust tool for and intrusion detection system (IDS), snort bundles swatch with other tools to provide a more comprehensive solution. I'm using swatch to monitor non-system application logs. Otherwise, you're probably reinventing the wheel.

The swatch command: Code:

swatch --config-file=swatch-auth.conf --tail-file=/var/log/auth.log --tail-args=--follow=name --daemon

   swatch -- by itself uses the hidden ~.swatchrc file as its config file and the /var/logs/syslog as the tail file to watch.
   --config-file=<filename> -- tells swatch to use a different config file.
   --tail-file=<filename> -- tells swatch to use a different tail file (the log to watch).
   --tail-args=--follow=name -- tells the tail program to use the --follow=name argument instead of the -f argument. This keeps tail from "stopping" when the log rotates because tail --follow=name follows the filename, not the node id as tail -f does. Tail looks like it stopped because you're still tailing the old rolled off log file. This precludes the need to stop and start swatch for log rolling.
   --daemon -- tell swatch to run the process in the background so you don't have to leave it open in an authenticated terminal.

A sample config entry to send an email (using postfix's sendmail interface) and a text message (ATT -- look up your carrier) when someone tries to su to root:

Code:

watchfor /FAILED su for root/

       exec echo "Subject: auth: FAILED su for root\n\n$_\n" | sendmail "sysadmin@mydomain.org;5555555555@txt.att.net"

   FAILED su for root -- the regular expression to trigger on
   exec -- executes an external command without stopping swatch to do it. In this case an echoed email piped into sendmail.
   Subject: auth: FAILED su for root -- the email subject as postfix/sendmail expects it. You could add From, To, etc to make it more robust.
   \n -- line feeds. I hope those are self-explanatory.
   $_ -- prints the flagged log line, not $0 or $* as the man page states!

2.15. Logging to Email Problem

You want to send your Snort logs to email. Solution

First, configure snort.conf to log alerts to syslog:

# alert_syslog: log alerts to syslog
# ----------------------------------
# Use one or more syslog facilities as arguments.  Win32 can also
# optionally specify a particular hostname/port.  Under Win32, the
# default hostname is '127.0.0.1', and the default port is 514.
# 
# [Unix flavours should use this format...]
output alert_syslog: LOG_AUTH LOG_ALERT
#
# [Win32 can use any of these formats...]
# output alert_syslog: LOG_AUTH LOG_ALERT
# output alert_syslog: host=hostname, LOG_AUTH LOG_ALERT
# output alert_syslog: host=hostname:port, LOG_AUTH LOG_ALERT

Snort sends alerts to the syslog file with the snort: prefix. Edit /.swatchrc to send an email when a Snort event is added to the syslog:

watchfor /snort:/
mail security@company.com,subject=Snort Alert!

Next, make sure you run Swatch to watch for syslog messages in /var/log/messages (some distributions use /var/log/syslog):

[root@localhost root]# swatch -t /var/log/messages

Lastly, run Snort in NIDS mode to use the snort.conf file to invoke the syslog output plug-in:

[root@localhost snort-2.2.x]# snort -l /var/log/snort -c /etc/snort.conf

Discussion

The easiest way to receive Snort alerts via email is to configure Swatch (available at http://swatch.sourceforge.net/) to monitor syslog and send an email when a Snort event is produced. Swatch is a log-monitoring utility that can filter messages from logfiles ...

swatch - Simple Log Analyzer

swatch is a perl program that can run as a daemon and continiously analyze log files for certain patterns to appear and then trigger an email notification.

You do definitley need a working MTA (e.g. dma or postfix) installed on ipfire for swatch to actually work.

Furthermore you need a configuration file that tells swatch for which patterns it should look out and which action to trigger. For Example sending email notification on SNORT prio 1 and 2 alerts, would look like this:

watchfor /Priority\: ([1|2])/
echo=normal
mail=alerts@your.domain,subject=[SNORT] Priority $1 Alert

Put this config in a file, e.g. /var/ipfire/snort/swatchrc

Then tell swatch to start in daemon mode and read in the snort log file in “tail” mode. As SNORT alert log entries are multiline texts, seperated by 2 newlines, we also tell swatch to use the 2 new lines as a seperator:

/usr/bin/swatch --daemon -c /var/ipfire/snort/swatchrc --input-record-separator='\n\n' -t /var/log/snort/alert

To start this automatically at system startup, best put it in

/etc/sysconfig/rc.local

swatch, despite being named “simple” is a very powerful tool that can be used for all sorts of neat stuff. Here is another example about what can be done:

Referensi

• https://www.safaribooksonline.com/library/view/snort-cookbook/0596007914/ch02s16.html
• http://wiki.ipfire.org/en/addons/swatch/start
• https://ubuntuforums.org/showthread.php?t=1035589