[Bro] Bro Log ingestion

Hosom, Stephen M hosom at battelle.org
Thu Sep 18 05:01:11 PDT 2014

If you need a protocol that plays well with Logstash, can operate on a custom ‘low port’ (sigh…), and also supports encryption, you have described lumberjack. Lumberjack is supported by Logstash Agent (when you run full blown logstash on the Bro boxes as forwarders) or a smaller, more slim application called Logstash-Forwarder. You’re going to limit yourself a lot by using that configuration though. First of all, you’re going to need to have a very good working knowledge of TLS. The Logstash-Forwarder and Agent are both very picky about their TLS and requests to have options allowing for users to circumvent some of the checks have been largely met with opposition.

As far as getting Logstash to connect to your elasticsearch cluster, the documentation is very clear. Depending on which version of elasticsearch you’re using, the steps will vary. If you want some help configuring it, I could help you offline… seems like a pretty big distraction for me to send Logstash and Elasticsearch configuration tips on this mailing list ☺

From: bro-bounces at bro.org [mailto:bro-bounces at bro.org] On Behalf Of Jonathon Wright
Sent: Wednesday, September 17, 2014 6:38 PM
To: Donaldson, John
Cc: bro at bro.org
Subject: Re: [Bro] Bro Log ingestion

Excellent information James. Thanks also for the vote of confidence too John, but you guys are making it harder, haha. It seems I need more information to determine the best course as the opinions are varied over using Splunk or LogStash.

James, couple questions on your post.

So if I understand correctly, ElasticSearch is what listens (as a Virtu Apache module I'm assuming?), LogStash merely feeds ElasticSearch the logs. Getting logs to the server that is running LogStash and ElasticSearch is where Rsyslog-vs-Splunk-vs-whatever else comes into play...correct?

You indicated "Rsyslog on my sensors have been excellent to pipe to a listening Logstash instance (high ports mean I can run as standard user)." Does this mean you have LogStash listening on a high port where rsyslog connects too? If so, this would be a problem for me. In my over regulated environment, the logs have to be transferred on a low port, preferrably on a known standard port (such as ssh/22), and the logs must be transferred on an encrypted channel. This is the main reason I initially wanted to use rsync, which uses ssh, encrypts the connection, and obviously runs on a known/standard low port, 22. The problem being that rysnc runs with permissions of the thread owner, in this case a non-root user. And since root is not allowed to SSH into a box, I cannot use rsync. So... can you elaborate a bit more on what ports you are using (or is it random high ports), and if its encrypted, or if you have any other thoughts on how I can solve the movement of the Bro logs in a secure manner?

Once I have a good solution for getting the Bro logs over to the collector/apache server, I'd be real excited to discuss some more details about logstash.conf and configuring it to feed ElasticSearch.

Any additional thoughts from the group are welcome, thanks again for the assistance thus far!

On Wed, Sep 17, 2014 at 11:08 AM, Donaldson, John <donaldson8 at llnl.gov<mailto:donaldson8 at llnl.gov>> wrote:
We also feed our Bro logs into Splunk and have been pretty happy with that. We have a pretty good idea of what our daily volume looks like, and have been able to plan comfortably around that. We’ve only been bitten by unusually large spikes in volume once or twice in the couple of years that we’ve been Splunking our data.

John Donaldson

From: bro-bounces at bro.org<mailto:bro-bounces at bro.org> [mailto:bro-bounces at bro.org<mailto:bro-bounces at bro.org>] On Behalf Of John Landers
Sent: Wednesday, September 17, 2014 1:09 PM
To: Jonathon Wright; Stephen Reese

Cc: bro at bro.org<mailto:bro at bro.org>
Subject: Re: [Bro] Bro Log ingestion

As it relates to Splunk, you can consume the data in a number of ways. I use a universal forwarder – agent on the box – and configure it to monitor the logs I want to consume (conn.log, dns.log, files.log, etc.) in the Bro “current” working directory.

So, as Bro logs it to file, it gets replicated to the Splunk indexer by the agent. Once the file roles, I don’t care anymore. Though if you wanted to ingest old logs, that would pretty easy to accomplish as well. (Just reference splunk documentation on the inputs.conf config file.)

John Landers

From: bro-bounces at bro.org<mailto:bro-bounces at bro.org> [mailto:bro-bounces at bro.org] On Behalf Of Jonathon Wright
Sent: Wednesday, September 17, 2014 2:26 PM
To: Stephen Reese
Cc: bro at bro.org<mailto:bro at bro.org>
Subject: Re: [Bro] Bro Log ingestion

Quite the responses, thanks!

Here are my thoughts.

I saw your post Doug, and on some of our projects we can use Security Onion w/Bro and ELSA, but in this case it must be a RHEL based solution. The solution Stephen R. demo'd with the Kibana approach [1] is pretty nice. But it brought an issue to my attention. It appears that Logstash needs to startup listening on a different port, 9292. I'm wondering if I missed something or why Kibana wouldn't simply run as a plugin or additional module under apache on port 443. We are in a highly regulated network, and if I stand up an Apache server (where all the Bro logs are going to be placed), and the Apache server is listening on a non secure (!443) port such as 9292, then it causes flags to be thrown up everywhere and always kills my project. Additional thoughts on that?

Stephen H, not a nit-pick at all, great post! =) My method for moving the logs from all the seensors to a central collector at this point are still in the works. My best route is probably to use 'rsync'. The problem I have right now is that Bro logs and extracted files have 600 permissions when they are created. The cause is simply the umask for root on the servers, which is set to 077. Since the servers are configured (correctly) to not allow SSH by root, then my rsync proposal also died since all the files are accessible by root only. Also, I'm unable to change the umask of root (regulations not know how) so short of creating an every minute chmod 644 cronjob, I'm scratching my head on how to get the logs over to the collector/ apache server.

You make an excellent point though " The downside is that this can require quite the large amount of infrastructure… and the only way to find out exactly how much your environment will need is to build it and see. It also requires that you keep up to date in knowledge on 3 pieces of software and how they interact…"
The knowledge and infrastructure count / increase is a large flag that will prohibit that endeavor (but great to know about).

Both you, John L., and Will H. indicate Splunk though as your solution which gives me another option.  But I have the same "question about ingestion" =) How did you get the logs from the multiple sensors to the "ingestion / collector server"? Rsync, SCP, owner / permission issues? I'm interested for sure. But.....the cost is a big no-no as well. As Will H. indicated the cost can go up based on usage, I do need a truly open-source free solution, so I am now leaning back to ElasticSearch / LogStash unless I missed something.

Paul H. , you get to use FreeBSD... <drool>... Man do I miss FreeBSD! Give me packages or give me death, haha. Ever since we were forced to use RHEL I miss it more and more! But to your comments, this sentence really caught my attention: "...the logs are sent to a collector via syslog-ng.." Then you said "There, they are written to disk where they are read by logstash and sent to elasticsearch". Since I'm leaning in the Logstash / ElasticSearch method, based on above thoughts, can you share a bit more on how you set up the syslog-ng, logstash, elasticsearch? That seems to be really close to meeting my requirement. I'm assuming you installed them as source and set them in the rc.conf to enabled YES to startup on boot. I'm more interested in the details of the conf files on with what arguments the daemons start up and especially how you were able to get the syslog-ng piece working between the sensor and the collector.

[1] http://www.appliednsm.com/parsing-bro-logs-with-logstash/

Thanks again to all, this is great stuff.


On Wed, Sep 17, 2014 at 4:42 AM, Stephen Reese <rsreese at gmail.com<mailto:rsreese at gmail.com>> wrote:

As pointed out, a Redis solution may be an ideal open-source route, e.g. http://michael.bouvy.net/blog/en/2013/11/19/collect-visualize-your-logs-logstash-elasticsearch-redis-kibana/

On Wednesday, September 17, 2014, Hosom, Stephen M <hosom at battelle.org<mailto:hosom at battelle.org>> wrote:

As a nit-pick, just because the files are owned by root, doesn’t mean they aren’t world-readable. ☺ The absolute simplest solution to allow the logs to be viewable by non-root users is to scp them to a centralized server, but I’m guessing you want something a little fancier than that.

If you can do it, go with free Splunk. If you can afford it, go with paid Splunk.


For log viewing with Elasticsearch Kibana works great, but, you could also check out Brownian: https://github.com/grigorescu/Brownian.

For log storage, if you want to consider something other than Elasticsearch, VAST is an option! https://github.com/mavam/vast There’s no GUI, so that might be a downer for you.

As far as Elasticsearch architecture goes, using Bro to write directly into Elasticsearch is definitely the easiest option. The only concern with this setup is that if Elasticsearch gets busy, nobody is happy. Elasticsearch has a tendency to drop writes when it is too occupied. This combined with the fact that (to the best of my knowledge) the Elasticsearch writer is a ‘send it and forget it’ could result in some hardship if you under build your Elasticsearch cluster or you undergo a period of unusually high utilization.

Seth has some interesting stuff using NSQ that he has written, but I’m not sure that it is technically ‘supported’. His NSQ stuff allows you to send the events to Elasticsearch at a rate that Elasticsearch is comfortable with.

Lastly, you could use the Logstash agent to send logs to a Redis server, which buffers the logs for additional Logstash agents to pull from and parse to insert into Elasticsearch. At the moment, I think that this is the most redundant setup. If you want as many logs to make it into Elasticsearch as possible while keeping the Bro side of things as simple as possible, this is likely the way to go. The downside is that this can require quite the large amount of infrastructure… and the only way to find out exactly how much your environment will need is to build it and see. It also requires that you keep up to date in knowledge on 3 pieces of software and how they interact…

Hopefully that helps at least a little!


From: bro-bounces at bro.org<mailto:bro-bounces at bro.org> [mailto:bro-bounces at bro.org] On Behalf Of Jonathon Wright
Sent: Tuesday, September 16, 2014 11:04 PM
To: Stephen Reese
Cc: bro at bro.org<mailto:bro at bro.org>
Subject: Re: [Bro] Bro Log ingestion

Thanks Steven, I'll take a look at those.
I'm assuming my central point server would then need Apache with ElasticSearch and Kibana installed. I'm sure more questions will come as I start looking into this. Thanks again for the info!

On Tue, Sep 16, 2014 at 4:28 PM, Stephen Reese <rsreese at gmail.com<mailto:rsreese at gmail.com>> wrote:
On Tue, Sep 16, 2014 at 9:54 PM, Jonathon Wright <jonathon.s.wright at gmail.com<mailto:jonathon.s.wright at gmail.com>> wrote:
Looking around and doing some reading, I've found two possible solutions ELSA and LOGSTASH although I don't know them very well and / or what their capabilities are either. But I'd like to know if they are viable, especially given my scenario, or if there is something better. Also, a how-to so I can set it up.

You might want to skip on the Logstash piece and push the data directly to ElasticSearch per [1] unless you have a specific requirement. From there you could use Kibana [2] or whatever to interface with data stored in ElasticSearch.

[1] https://www.bro.org/sphinx/frameworks/logging-elasticsearch.html
[2] http://www.elasticsearch.org/overview/kibana/

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