@menu
* Download ::
* Install ::
* Bro Configuration ::
* OS Configuration ::
* Encrypted Reports ::
* Generating Reports on a Separate Host ::
@end menu

@node Download
@section Download
@cindex download

Download Bro from: @uref{http://www.bro-ids.org/}

You can unpack the distribution anywhere except into the directory
you plan to install into. To untar the file, type:

@example
tar xzf bro-pub-0.9-current.tar.gz
@end example

@node Install
@section Install
@cindex BROHOME

You'll need to collect the following information before beginning the installation.

@itemize
@item localnets: a list of local subnets for your network. Bro needs to know which networks are "internal" and which are "external".

@item interface names: the names of the capture interfaces in your host (e.g. sk0 or en1). Use @code{ifconfig -a} to get the list of all network interfaces on your Bro host.
@end itemize

If you want to use Bro's periodic email report feature, you'll also need:
@itemize
@item email list: a list of email addresses to send the reports to.

@item PGP keys: if you want to encrypt all email reports, the location of the 
@uref{http://www.gnupg.org/,GPG keyring} of all recipients.
@end itemize

Bro is easy to install. Log in as @code{root}, and type:
@example
./configure
@end example
By default Bro is installed in @code{/usr/local/bro}. 
This location
is referred to in the rest of the manual as @code{$BROHOME}.
To install Bro in a location other than @file{/usr/local/bro}, use:
@example
./configure --prefix=/path/to/bro
@end example
By default Bro uses the version of libpcap that is installed on
the system. If your system version older than version 0.7.2, you can run configure
Bro with --enable-shippedpcap to use the version of libpcap that comes packaged
with Bro. For example:
@example
./configure --enable-shippedpcap
@end example

Then type:
@example
make
make install
@end example
or
@example
make install-brolite
@end example

Use @emph{make install} to install all the Bro binaries and policy script files. Use
@emph{make install-brolite} to also run the configuration script (described in the next section) and install all the configuration files and @code{cron} jobs. @emph{make install} can be run as any user, but @emph{make install-brolite} requires
you to be root.

To update an existing Bro installation with new binaries and standard policy files, instead
of @code{"make install"} do a @code{"make update"}. This will preserve all your local customizations.

Then add @code{$BROHOME/bin} and @code{$BROHOME/scripts} to your $PATH to use
Bro's utilities and scripts.

Also note that this documentation is installed in @code{$BROHOME/docs} as both HTML and PDF versions.

@node Bro Configuration
@section Bro Configuration
@cindex bro_config
@cindex bro.cfg

The @emph{Bro-Lite} configuration script can be used to automatically configure (or reconfigure) Bro for you. It
checks your system's BPF settings, creates a "bro" user account, installs
a script to start Bro at boot time, installs the report generation package,
and installs a number of @code{cron} jobs 
to checkpoint Bro every night, run periodic reports, and manage log files.

To run this configuration script type:
@example
bro_config
@end example


This script creates the file @file{$BROHOME/etc/bro.cfg}.
@code{bro_config} will ask a number of simple questions. Note
that the full functionality of this script is only supported
under FreeBSD. Some additional configuration may need to be
done by hand under Linux.

Sample output of @code{bro_config}, along with explanation, is shown below:

@quotation

@verbatim
Running Bro Configuration Utility
Checking interfaces ....  Done.
Reading /usr/local/bro/etc/bro.cfg.example for defaults.
@end verbatim
@quotation 
@quotation 
The @code{bro_config} script looks first at ./bro.cfg, then /usr/local/bro/etc,  
for default values to use below.
@end quotation
@end quotation

@verbatim
Bro Log archive location [/usr/local/bro/archive] 
@end verbatim
@quotation
@quotation
This is the directory where log file archives are kept. 
If you expect the log files to be very large, it is recommended to put these in a separate disk partition.
@end quotation
@end quotation

@verbatim
User id to install and run Bro under [bro] 
@end verbatim
@quotation
@quotation
@code{bro_config} will create a new user account with this username if the user does not exist. 
@end quotation
@end quotation

@verbatim
Interface names to listen on. [en1,en2] 
@end verbatim
@quotation
@quotation
@code{bro_config} looks for all network interfaces and does a short test to determine which interfaces see the most traffic, and selects these interfaces as the default. 
@end quotation
@end quotation

@verbatim
Site name for reports (i.e. LBNL, FOO.COM, BAZ.ORG) [] 
Starting Report Time [0600]
Report interval (in hours) [24]
Email addresses for reports [bro@localhost] 
@end verbatim

@quotation
@quotation
Daily reports will be created.  
Enter the site name you want to appear at the top and in the subject of all email reports.
The "start time" and "interval" define the window of 
network activity that the daily report will cover, starting at "Starting Report Time" and 
lasting through "Report interval". The start time should be entered using 24hr clock notation. 
For example: 12:30AM = 0030,  2PM = 1400
@end quotation
@end quotation


@verbatim
Do you want to encrypt the email reports (Y/N) [N]
Y
@end verbatim
@quotation
@quotation 
If you want the email reports encrypted, you will need to set up GPG (@uref{http://www.gnupg.org})
and create a GPG keyring containing the public keys of all email recipients. Instructions 
for this are in @ref{Encrypted Reports}.
@emph{Note: PGP keys are compatible with GPG, but the Bro supplied scripts 
require GPG, not PGP}.

@end quotation
@end quotation

@verbatim
Running script to determine your local subnets ... 
Your Local subnets [198.129.224.1/32] 
@end verbatim

@quotation
Bro needs to know a list of your local subnets. @code{bro_config} runs a tool 
that attempts to discover this automatically. 
You should always verify the results of this tool. The format is a list of subnet/significant 
bits of address. 
For example: 131.243.0.0/16, 198.128.0.0/18, 198.129.224.1/32
This information will be stored in the file @code{$BROHOME/site/local.site.bro}
@end quotation

@verbatim
Saving settings to file: /usr/local/bro/etc/bro.cfg
Bro configuration finished. 
To change these values, you can rerun bro_config at any time.
@end verbatim
@quotation
Indicates that the script finished successfully.
@end quotation

@end quotation

For site monitoring very high traffic rates on Gigabit Ethernet, there is some
additional system tuning that should be done. See the @ref{Performance Tuning} 
section for more details.

To reconfigure Bro, run:
@example
BRHOME/scripts/bro_config
@end example

This will update your @file{/usr/local/bro/etc/bro.cfg} file. You can also edit this file using your favorite editor if you prefer.

For other site customizations, you can edit the file $BROHOME/site/brohost.bro.
For example, to tell bro to not look at traffic for host 198.162.44.66, add:
@verbatim
     redef restrict_filters += {
       ["ignore host 198.162.44.66 "] =
	 "not host 198.162.44.66"
     };
@end verbatim

More details are available in the section on @ref{Customizing Bro}.

@node OS Configuration
@section OS Configuration

This section contains information on critical OS tuning items. More detailed
tuning information can be found in the section on @ref{Performance Tuning}.

@strong{FreeBSD Configuration}

The standard FreeBSD kernel imposes a per-process limit of 512 MB of memory.
This is not enough for most Bro installations. 

To check your current limit type:

@smallexample
limits -H
@end smallexample

Unfortunately the only way to increase this limit in FreeBSD 4.x
is to reconfigure and rebuild the kernel.
In FreeBSD 5.x it is much easier. Just increase
@code{kern.maxdsiz} in @file{/boot/defaults/loader.conf} and reboot.
For example:
@smallexample
kern.maxdsiz="2G"
@end smallexample


and look at the @code{datasize} setting, which should be the same
as your amount of RAM. If this is not true, see section @ref{Hardware and OS Tuning}
for information on fixing this.

For FreeBSD 5.3+, BPF devices are no longer created using MAKEDEV, but rather are
created on demand. This is configured automatically by running '@code{make install-brolite}',
or you can figure it by hand by adding the following to @code{/etc/rc.local}

@verbatim
devfs ruleset 15
devfs rule add 15 path 'bpf*' mode 660 user bro
@end verbatim
 

@strong{Linux Configuration}

You may want increase these for a high traffic environment.

@emph{not done: need to get recommended values for these}:

@verbatim
/proc/sys/net/core/rmem_default (IP-Stack socket receive queue)
/proc/sys/net/core/rmem_max     (similar to rmem_default)
/proc/sys/net/core/netdev_max_backlog (queue between driver and socket)
@end verbatim


@node Encrypted Reports 
@section Encrypted Reports 
@cindex GPG

Bro can use GPG (@uref{http://www.gnupg.org/}) to encrypt
the reports that it sends. To have Bro encrypt your
reports you must have said "yes" to the bro_config question to
encrypt your reports. 
Then each email recipient much generate a public/private key pair, and their public key 
must be installed on the Bro machine in the home directory of the user running
the Bro process.

To create a key-pair:

@example
gpg --gen-key
@end example

To export the public key:

@example
gpg --armor --output mykey.gpg --export myemail@@address.com
@end example

Then login to the machine running Bro and import the list of public keys:

@example
gpg --import mykey.gpg
@end example


Then you must to make the list of keys "trusted" so that they can be used
to encrypt the email reports. To do this, you must 
edit the key to add "ultimate" trust to the key.

@example
gpg --edit-key myemail@@address.com

pub  1024D/4A872E40  created: 2001-02-05 expires: never      trust: -/f
sub  3072g/B72DD7FE  created: 2001-02-05 expires: never     
(1). Some R. User <myemaill@@address.com>

Command> trust
pub  1024D/4A872E40  created: 2001-02-05 expires: never      trust: -/f
sub  3072g/B72DD7FE  created: 2001-02-05 expires: never     
(1). Some R. User <myemail@@address.com>

Please decide how far you trust this user to correctly
verify other users' keys (by looking at passports,
checking fingerprints from different sources...)?

 1 = Don't know
 2 = I do NOT trust
 3 = I trust marginally
 4 = I trust fully
 5 = I trust ultimately
 m = back to the main menu

Your decision? 5
Do you really want to set this key to ultimate trust? yes

pub  1024D/4A872E40  created: 2001-02-05 expires: never      trust: u/u
sub  3072g/B72DD7FE  created: 2001-02-05 expires: never     
(1). Some R. User <myemail@@address.com>

Command> quit

@end example

For more information on GPG see @uref{http://www.gnupg.org/}

@node Generating Reports on a Separate Host 
@section Generating Reports on a Separate Host 
@cindex report generate, separate host
@cindex GPG

@emph{Warning: this section assumes a reasonably high level of Unix system administration skills!}

If your site has lots of traffic, lots of connections, or if Bro is using on average more than around 40% of your CPU,
you'll want to use a second host for generating reports.

To do this, on the Bro host, run bro_config, and say "N" to all report generation questions.
Then install Bro on the second host using the following:

@example
./configure
make
make install-reports
@end example

Then follow the instructions in @ref{Bro Configuration} for setting up report generation.

You'll also need to set up a method to copy files from the Bro host to the report generation
host. One way to do this is using @code{rsync}, and the Bro script @code{push_logs.sh} 
does this for you. For example, you can set up a cron job
like this on the Bro host:

@example
1 1 * * * (push_logs.sh /usr/local/bro/etc/bro.cfg host:/home/bro) >> /tmp/bro-push.log
@end example

To make sure your @code{rsync} command has time to transfer
all log files before your report generation
script is run, the @code{push_logs.sh} script is designed to be used with the scripts
@code{frontend-site-report.sh} and @code{frontend-mail-report.sh} on the frontend host. 
These @code{frontend} scripts wait for a file with a particular name to exist before running.
It is also important to use the @code{nice} 
command to help ensure the network copy does not unduly divert processing away from Bro.

You may want to @code{rsync} the log files over a secure ssh connection. To do this,
you need to first generate a ssh key pair on the Bro capture host with no passphrase:
@example
ssh-keygen -t rsa -C "batch key" -f ./batch.key
@end example

Put this in user @code{bro}'s .ssh/config file, also on the Bro capture host
@example
Host recvhost brohost.foo.com
IdentityFile ~/.ssh/batch.key
@end example

On the frontend host where the log files will be processed, add batch.pub 
to the authorized_keys file
@example
cat batch.key.pub >> authorized_keys
@end example

Then create a cron entry on the Bro capture host 
@example
1 1 * * * nice -n 20 rsync -e 'ssh' -azv \
  /usr/local/bro/logs host:/home/bro
@end example

@comment @node Web GUI Installation / Configuration 
@comment @section Web GUI Installation / Configuration 

@comment The Bro Web Logfile viewing GUI is not yet packaged in an easy to install format.
@comment However if you want to give try installing it, there are
@comment instructions at:
@comment @uref{http://www.icir.org/twiki/bin/view/Bro/BrooeryGUI/}
@comment 
@comment This web GUI can run on a lightly loaded Bro host, but it is recommended to run this on a separate host. Use the @code{rsync} method described in 
@comment @ref{Generating Reports on a Separate Host} to
@comment copy files to the web host. Note: this web server should NOT be publicly accessible
@comment to the Internet. Information in the log files is generally very sensitive.
@comment