Red Hat (RHEL) System Logs

We recommend using Filebeat to upload logs locally from Red Hat to Logstash.

sudo rpm --import https://artifacts.elastic.co/GPG-KEY-elasticsearch
echo "[elastic-6.x]
name=Elastic repository for 6.x packages
baseurl=https://artifacts.elastic.co/packages/oss-6.x/yum
gpgcheck=1
gpgkey=https://artifacts.elastic.co/GPG-KEY-elasticsearch
enabled=1
autorefresh=1
type=rpm-md" | sudo tee /etc/yum.repos.d/elastic-beats.repo

sudo yum install filebeat

/etc/filebeat/filebeat.yml

There are several built in filebeat modules you can use. To enable the system module run.

sudo filebeat modules list
sudo filebeat modules enable system

Additional module configuration can be done using the per module config files located in the modules.d folder, most commonly this would be to read logs from a non-default location

deb/rpm /etc/filebeat/modules.d/
mac/win <EXTRACTED_ARCHIVE>/modules.d/

We'll be shipping to Logstash so that we have the option to run filters before the data is indexed.
Comment out the elasticsearch output block.

## Comment out elasticsearch output
#output.elasticsearch:
#  hosts: ["localhost:9200"]

Uncomment and change the logstash output to match below.

output.logstash:
    hosts: ["your-logstash-host:your-ssl-port"]
    loadbalance: true
    ssl.enabled: true

All Logit stacks come pre-configured with popular Logstash filters. We would recommend that you add system specific filters if you don't already have them, to ensure enhanced dashboards and modules work correctly.

Edit your Logstash filters by choosing Stack > Settings > Logstash Filters

if [fileset][module] == "system" {
  if [fileset][name] == "auth" {
    grok {
      match => { "message" => ["%{SYSLOGTIMESTAMP:[system][auth][timestamp]} %{SYSLOGHOST:[system][auth][hostname]} sshd(?:\[%{POSINT:[system][auth][pid]}\])?: %{DATA:[system][auth][ssh][event]} %{DATA:[system][auth][ssh][method]} for (invalid user )?%{DATA:[system][auth][user]} from %{IPORHOST:[system][auth][ssh][ip]} port %{NUMBER:[system][auth][ssh][port]} ssh2(: %{GREEDYDATA:[system][auth][ssh][signature]})?",
                "%{SYSLOGTIMESTAMP:[system][auth][timestamp]} %{SYSLOGHOST:[system][auth][hostname]} sshd(?:\[%{POSINT:[system][auth][pid]}\])?: %{DATA:[system][auth][ssh][event]} user %{DATA:[system][auth][user]} from %{IPORHOST:[system][auth][ssh][ip]}",
                "%{SYSLOGTIMESTAMP:[system][auth][timestamp]} %{SYSLOGHOST:[system][auth][hostname]} sshd(?:\[%{POSINT:[system][auth][pid]}\])?: Did not receive identification string from %{IPORHOST:[system][auth][ssh][dropped_ip]}",
                "%{SYSLOGTIMESTAMP:[system][auth][timestamp]} %{SYSLOGHOST:[system][auth][hostname]} sudo(?:\[%{POSINT:[system][auth][pid]}\])?: \s*%{DATA:[system][auth][user]} :( %{DATA:[system][auth][sudo][error]} ;)? TTY=%{DATA:[system][auth][sudo][tty]} ; PWD=%{DATA:[system][auth][sudo][pwd]} ; USER=%{DATA:[system][auth][sudo][user]} ; COMMAND=%{GREEDYDATA:[system][auth][sudo][command]}",
                "%{SYSLOGTIMESTAMP:[system][auth][timestamp]} %{SYSLOGHOST:[system][auth][hostname]} groupadd(?:\[%{POSINT:[system][auth][pid]}\])?: new group: name=%{DATA:system.auth.groupadd.name}, GID=%{NUMBER:system.auth.groupadd.gid}",
                "%{SYSLOGTIMESTAMP:[system][auth][timestamp]} %{SYSLOGHOST:[system][auth][hostname]} useradd(?:\[%{POSINT:[system][auth][pid]}\])?: new user: name=%{DATA:[system][auth][user][add][name]}, UID=%{NUMBER:[system][auth][user][add][uid]}, GID=%{NUMBER:[system][auth][user][add][gid]}, home=%{DATA:[system][auth][user][add][home]}, shell=%{DATA:[system][auth][user][add][shell]}$",
                "%{SYSLOGTIMESTAMP:[system][auth][timestamp]} %{SYSLOGHOST:[system][auth][hostname]} %{DATA:[system][auth][program]}(?:\[%{POSINT:[system][auth][pid]}\])?: %{GREEDYMULTILINE:[system][auth][message]}"] }
      pattern_definitions => {
        "GREEDYMULTILINE"=> "(.|\n)*"
      }
      remove_field => "message"
    }
    date {
      match => [ "[system][auth][timestamp]", "MMM  d HH:mm:ss", "MMM dd HH:mm:ss" ]
    }
    geoip {
      source => "[system][auth][ssh][ip]"
      target => "[system][auth][ssh][geoip]"
    }
  }
  else if [fileset][name] == "syslog" {
    grok {
      match => { "message" => ["%{SYSLOGTIMESTAMP:[system][syslog][timestamp]} %{SYSLOGHOST:[system][syslog][hostname]} %{DATA:[system][syslog][program]}(?:\[%{POSINT:[system][syslog][pid]}\])?: %{GREEDYMULTILINE:[system][syslog][message]}"] }
      pattern_definitions => { "GREEDYMULTILINE" => "(.|\n)*" }
      remove_field => "message"
    }
    date {
      match => [ "[system][syslog][timestamp]", "MMM  d HH:mm:ss", "MMM dd HH:mm:ss" ]
    }
  }
}

Let's check the configuration file is syntactically correct. Run from extracted archive directory.

sudo filebeat -e -c filebeat.yml

Ok, time to start ingesting data!

sudo systemctl enable filebeat
sudo systemctl start filebeat

Red Hat Enterprise Linux (RHEL) is the most popular commercial Linux distribution used in public cloud environments.

Red Hat Enterprise Linux is often compared to CentOS. The main difference between the two Linux distributions is that RHEL offers a much more comprehensive level of technical support to their users.

Red Hat Enterprise Linux generates a near overwhelming amount of log files under the /var/log/ directory. Just under /var/log/messages alone there are mail, cron, daemon, kern & authentication logs.

Below are some of the most notable log directories that you’ll commonly encounter.

If you are using custom-built Kernels then you’ll likely need to analyse the logs contained under /var/log/kern.log when it comes to troubleshooting your application.

The log messages found under /var/log/secure are relevant for monitoring the security of your Linux distribution as they contain authentication events, login attempts & authorisation log events.

You may also wish to consult /var/log/setroubleshoot/ to discover issues related to the security context of logs files created under this directory.

With over 25 different log directories anyone would quickly find analysing their Red Hat system overwhelming without a log file analyser as part of a centralised log management solution.

Our HA (highly available) Red Hat log file analyser can be used to completely centralise and manage your log file data across Red Hat & any additional applications, servers & programming languages for a single source of truth for monitoring across your organisation.

If you need any assistance with analysing your Red Hat logs we're here to help. Feel free to reach out by contacting the Logit support team via live chat & we'll be happy to help you start analysing your data.