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IRJET-IMPORTANCE OF CENTRALIZED LOG SERVER AND LOG ANALYZER SOFTWARE FOR AN ORGANIZATION

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Most of the enterprise organizations in the last few years have designed their network infra structure to higher levels of accountability and information security standards. Information Security Regulatory bodies have implemented a substantial number of regulations which forced the organizations to focus on their information security standards. One of the major guidelines provided by the regulatory bodies is to focus on collection, retention and review of logs from their application servers and network servers like e-mail server, firewall server, web server, proxy server, etc., Log data of such organizational servers are their richest information asset for assessing security posture, tracking sophisticated threats, and meeting audit requirements. Because of their evidentiary value, logs must be managed as a legal record; they must be complete, accurate and verifiable1. Analysis of these log files are very difficult to do without the support of an external utility designed for analyzing such data. There are many log analysis programs available in the market for analyzing these log files but an indigenous program is needed for an organization to analyze its own server log data format. This paper highlights on the importance of Central log server and also the effectiveness of log analyzer software for analyzing the huge volume of log data fetched from all the network servers and appliances. It briefly discusses the indigenous log analyzer software developed for our organization.

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International Research Journal of Engineering and Technology (IRJET)

e-ISSN: 2395 -0056

Volume: 02 Issue: 03 | June-2015

p-ISSN: 2395-0072

www.irjet.net

IMPORTANCE OF CENTRALIZED LOG SERVER AND LOG ANALYZER
SOFTWARE FOR AN ORGANIZATION
R.Anusooya1, J.Rajan2, S.A.V.SatyaMurty3
1. Scientific Officer-E, Computer Division, Indira Gandhi Centre for Atomic Research, Tamilnadu, India
2. Scientific Officer-F, Computer Division, Indira Gandhi Centre for Atomic Research, Tamilnadu, India
3.Outstanding Scientist, Computer Division, Indira Gandhi Centre for Atomic Research, Tamilnadu, India
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Abstract - Most of the enterprise organizations in the
last few years have designed their network infra
structure to higher levels of accountability and
information security standards. Information Security
Regulatory bodies have implemented a substantial
number of regulations which forced the organizations
to focus on their information security standards. One of
the major guidelines provided by the regulatory bodies
is to focus on collection, retention and review of logs
from their application servers and network servers like
e-mail server, firewall server, web server, proxy server,
etc., Log data of such organizational servers are their
richest information asset for assessing security posture,
tracking sophisticated threats, and meeting audit
requirements. Because of their evidentiary value, logs
must be managed as a legal record; they must be
complete, accurate and verifiable1. Analysis of these log
files are very difficult to do without the support of an
external utility designed for analyzing such data. There
are many log analysis programs available in the
market for analyzing these log files but an indigenous
program is needed for an organization to analyze its
own server log data format. This paper highlights on
the importance of Central log server and also the
effectiveness of log analyzer software for analyzing the
huge volume of log data fetched from all the network
servers and appliances. It briefly discusses the
indigenous log analyzer software developed for our
organization.

Key words : Central Log Server, Log Server, Log
analyzer, Rsyslog, syslog
1. INTRODUCTION:
The servers on the Internet and Intranet produce diverse
and huge volume of logs. Obtaining relevant information
from these logs daily will be a challenging task for the
system / network administrator. For Example, e-mail
server / web server is an essential communication tool for
many industries, government and academic organizations.
These servers play a vital role in exchanging messages,
data files, images and voice messages over Internet. Since
these kinds of servers will be contacted by many servers
from the Internet, careful deployment planning according
to the organization’s security policy is needed. This
© 2015, IRJET.NET- All Rights Reserved

ensures that these servers have been installed, configured
and implemented in a secure manner. Logs of these
servers are the richest source of information in an
enterprise organization and it should be kept safe. Due to
its evidentiary value, logs must be managed as a legal
record; they must be complete, accurate and verifiable.1
Logs of servers will vary according to the organization’s
security policy and posture. So an in-house developed log
analyzer program will be an effective solution for an
organization to analyze its own servers log data format.
This paper discusses the importance of Central log server
and how the huge volume of log data of an organization is
converted into a meaningful Meta data and analyzed using
scripts and programs.

2. CENTRAL LOG SERVER
A centralized log server stores the real-time and archived
logs of various network services, hosts and appliances that
are used in the network and these logs are referred to for
troubleshooting, resource monitoring and security
analysis. The network servers, hosts and network
appliances keep their own logs and configured to
simultaneously send all local logs to a secured remote log
server. Storing the logs only on the host where the
message has been generated is problematic for several
security reasons.
To overcome these issues, a central log server with proper
security measures is needed. With good planning and
rigorous implementation of secure configurations and
operational procedures, organizations can operate
successful central logging system while protecting their
networks and information resources. Network devices and
operating systems generate text messages of various
events that happen to them like – login information, file
creation, server daemon statistics, user login, established
connections between remote hosts and intranet servers,
network activities, etc. These text messages are called log
messages, these messages can be used to detect security
incidents, operational problems, policy violations, and are
useful in auditing and forensics situations.
The figure (Fig – 1) illustrates that each and every
network device in an organizational network setup sends
the log messages to the central log server and the system

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administrator monitors the alerts and events generated by
all logs of the server by sitting in a centralized location.

Fig – 1: Typical Central syslog server setup
The log messages use the legacy syslog / rsyslog protocol,
which is supported by most of the UNIX distributions and
appliances. Recent Linux distributions come with the
“rsyslog” service. The “rsyslog” service replaces the
“syslog/syslog-ng” services of earlier linux distributions.
The “rsyslog” service has been implemented and is
available on virtually in every UNIX-like operating system,
and has become the de-facto standard of remote logging.
System administrators look at the syslogs as a critical
source to troubleshoot performance problems on syslog
supported systems & devices across the network. The
need for a complete sys-log monitoring solution is often
underestimated; leading to long hours spent sifting
through tons of syslogs to troubleshoot a single problem.
Efficient event log syslog analysis reduces system
downtime, increases network performance, and helps
tighten security policies in most of the organizations.
The following sections will briefly discuss on the
importance of central log server, benefits of “rsyslog”
service as it has more features when to the earlier “syslog
/ syslog-ng” service and the log analyzer software.

2.1 Aim of central log server
The aim of central logging system is to collect the log
messages from different network hosts like switches,
routers, firewall server, proxy server, e-mail server, web
server etc., into a single, central log server. The main
benefits of this server are listed below:
i.
Since the logs of all network hosts, appliances are
available at centralized location; an administrator
need not login individually to each of the network
hosts to check the logs.
ii.
A centralized log server helps nullify any system
overhead while running tools on logs, since the

© 2015, IRJET.NET- All Rights Reserved

logs on the central log server are essentially
offline to the hosts, applications etc.
iii.
Each networked hosts does not need to provision
disk space for logs that would accumulate over
time, instead only the last few days/weeks can be
retained on the client host and the server may be
configured to keep logs for a much farther time
span for the individual hosts, appliances, etc.
iv.
If the client host, appliance etc., goes offline for
some reason, the logs are still there to find out
what happened.
v.
Monitoring logs for security incidents are
proactive and the cheapest line of defense
towards an information security breach and is
one of the first step towards IT security.
The following section details how to setup a central log
server using a Linux host for the central log server.

2.2 Rsyslog configuration
System administrator monitors and responds immediately
to the critical events or an alert that takes place in a
network setup by implementing a suitable troubleshooting
mechanism. This troubleshooting mechanism can be
default software available with the operating system or an
in-house developed software solution. Rsyslog service is
one such mechanism to consolidate all logs from multiple
sources into a single location. Typically, most central
syslog servers have the following components that make
this possible.
a. Rsyslog service: Log server needs to receive messages
sent over the network. A listener process gathers
rsyslog data sent over reliable TCP transport. This
rsyslog service can also be used as a client as well as
for a relay server forwarding syslog messages from a
client to another server. Configurations are stores
under /etc/rsyslog.d/ directory.
b. Database: Large networks can generate a huge
amount of Syslog data. Good Syslog servers will use a
database to store syslog data for quick retrieval.
c. Management and filtering software: Because of the
potential for large amounts of data, it can be
cumbersome to find specific log entries when needed.
The solution is to use a syslog server that both
automates part of the work, and makes it easy to filter
and view important log messages.
The main configuration file is the rsyslog.conf file under
the /etc/ directory. “rsyslog” has the following sections a)
Configuration directives which are global, b) Templates
that format the message to be logged, c) Output modules
that write the message to their specified destination and
d) Rules that define the action to be taken on a match.
“rsyslogd” has been configured to accept remote messages
from different client machines. To configure the log server,
the client must be listed in /etc/rsyslog.conf, and the
logging facility must be specified,

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+client1.example.com
*.*
/var/log/client1.log
Once added, all facility messages will be logged to the file,
/var/log/client1.log. The log file should be created with
the following command,
# touch /var/log/client1.log

searching for log files easier than opening up a large log
file that was not set into log rotate12. Log file can be
compressed in gzip file format and can be rotated after a
specified number of weeks or months.

The following figure (Fig – 2) shows the sample rsyslog
configuration file with comments.

Log messages collected from different network hosts with
time-stamps should be routed for further analysis. The
following figure (Fig – 3) shows the routing of log
messages with rsyslog service collected from different
sources and filtered according to the application and
importance of the log data.

2.3.3 Log message routing

Fig – 3: Routing of Log messages using rsyslog

3. ROLE

OF

NTP

SERVER

IN

THE

ORGANIZATIONAL NETWORK SETUP

Fig – 2: Configuration file - rsyslog
The rsyslogd daemon should be restarted and verified:
# service rsyslogd restart
# ps –ef |grep rsyslog
If a PID is returned, the server has been restarted
successfully, and client configuration may begin. If the
server has not restarted, consult the /var/log/messages
log for any output. Now the servers configured with
rsyslog service will be able to generate alerts, notifications
and alarms in response to select messages. Now the
administrators will know as soon as a problem occurs and
can take faster action.

2.3 Features of “rsyslog”
2.3.1 Security
“rsyslog” supports TCP based network transport for
messages from log sources and has the ability to support
encrypting log traffic between client and server with TLS
(SSL). With this capability any organization may place
their log server and clients in remote geographies and use
the public Internet for transferring log data12.

2.3.2 Log rotation
Rotating the remote message logs on the server will save
precious disk space. Without rotating the log disk space
will just continue to grow eventually filling up drives. Log
rotation not only saves the disk space it will make
© 2015, IRJET.NET- All Rights Reserved

System log contains log messages with the following
information, i.e. the log message, the network
application/node/device/appliance and the time-stamp.
The time-stamp of an event is one of the most important
pieces of information in the logs. Administrator’s, quite
frequently need to refer to time-stamp’s in order to
correlate events that have occurred in the network. An
NTP server helps maintain the system date-time in all the
hosts in a network and is the one important service that
must be available to all hosts in a network while creating a
centralized log solution for an Organization12.

4. ROLE OF CENTRAL LOG SERVER FOR AN
ENTERPRISE ORGANIZATION
The most critical servers of an organization under
constant attack from spammers and hackers are e-mail
server / web server / application server. Even if they’re
not successful at stealing data or compromising the
network, spammers can cripple bandwidth, while hacks
such as relay theft can interfere with effective
communications and cause network instability. So
organizations should have an efficient central log server to
monitor all the network activities and should follow some
of the following best practices to keep their network
servers secure.
a. Dynamic network traffic inspection using Intrusion
Prevention system to block malicious network requests.
b. Keep virus and spam off the network before it can cause
trouble. Implementing effective filtering, proactive
monitoring, reputation filtering, Black listing domains,
etc.,

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c.

DMZ Zone should be isolated and no direct connection
to access the LAN by writing a rule in the firewall.
d. Restrictive mail relay parameters to avoid relay thefts.
e. Limit the number of connections allowed to your Web /
SMTP server to prevent DOS attacks.
f. Application servers are patched periodically to avoid
the exploitation of vulnerabilities in them.
g. Taking backup of Web server data / Mail boxes /
Application data on a regular basis.
h. Regular monitoring of Router / Firewall / Proxy server
logs.
i. Correct position of servers in an organization network.
j. Information security auditing of servers like firewall
(rules), NIPS rules, proxy settings, web server, SMTP
server, etc., on a regular basis are some of the best
practices organization should follow to avoid security
breach.
The following figure (Fig – 4) shows the typical network
setup of an enterprise organization.

event analysis and log management. So an in-house
developed, indigenous event analyzer and management
solution will help to solve these kinds of issues and it will
be easy for the system administrator to trace back any
kind of events that had happened in those servers with
this software solution. The log analyzer software analyzes
how the huge volume of log data is distinguished,
disseminated and presented after demystification. The
indigenously developed log analyzer program helps to
analyze the log Meta data viz; utilization of the
organizational service, security incident handling, domain
wise statistics, network data peak hour usage, individual’s
e-mail / web usage statistics, Internet and Intranet
applications usage statistics, periodical network statistics,
etc.,
The following sections will explain the log data analysis
software, its architecture and management.

6. LOG

DATA

ANALYSIS

SOFTWARE

ARCHITECTURE

Fig – 4: Typical Network setup in an Organization
This kind of multi-stage approach for keeping network
servers secure requires installation and configuration of
different servers like Firewall, Network Intrusion
Prevention system, Application level Firewall, SMTP
server at various levels of an organization’s network
setup. These servers will be configured with anti-spam,
anti-virus, anti-spyware, anti-malware software and also
with authentication and encryption features. Web servers
/ web application servers need be protected against sql
injection, cross site scripting attacks, etc., Services
supported by the web server / e-mail server / application
server should be well-defined according to the
organization’s security policy.

5. LOG ANALYZER SOFTWARE
As mentioned in the above section, a defense-in-depth
approach is needed for the smooth functioning of systems.
All these servers configured with proper security features
in addition to software configurations complicate the
© 2015, IRJET.NET- All Rights Reserved

Log data analysis is an important need of IT departments
in all organizations. These logs need to be collected,
analyzed, archived, searched and reports generated for the
purpose of IT security audit and compliance of various
regulatory acts. The log management can make serious
demands
on
an
organization’s
technological
infrastructure, many commercial hardware and software
vendors have attempted to meet the challenges of log
management by implementing common approaches. One
of the most common approaches is often built upon inhouse developed software created for e-mail and
computer systems. Such in-house software should deal
with terabytes of message data in logs alone, this
pressurizes system administrators and the risk
management team to decide what to keep and how to
manage the deluge of data with completeness, accuracy and
verifiability1.
a.

b.

c.

Completeness in the context of logs means that activity
is captured without gaps in time and collectively that
logs throughout an organization are mainlined in the
aggregate.
Accuracy means that the time, date and content of the
log are the same as when it was created. Electronic
copies are considered to be best evidence only if they
accurately reflect the original.
Verifiability - If logs are to earn the labels of complete
and accurate they must be verified as such. Some
techniques such as hashing, documenting each step of
the log management process and storing the data in
multiple separate locations are used for the
verification of logs.

If ensuring logs are complete, accurate and verifiable then
the first step is to manage logs and the next step is to
figure out how to turn all the data into an information

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resource. It is essential to be able to extract information
from the terabytes of enterprise log data for continuous
log data analysis and its management.

7. IN-HOUSE DEVELOPED LOG DATA ANALYSIS
SOFTWARE ARCHITECTURE

Log meta data analysis provides a dedicated section for log
data search, where the e-mail maillog, server / router
/switches messages, web access / secure log data stored in
database are searched and network anomalies or events
like mis-configurations, viruses, unauthorized access,
applications errors, etc., are detected.

As we have seen in the above sections that the commercial
and freeware software solutions available in the market
for log analysis and management will not be an effective
solution, it becomes mandatory for each system
administrator to develop indigenously developed software
compiled with their security policies for storing and
analyzing the log data. This log analysis software should
be web-based, real-time, log monitoring and compliance
management solution for Security Information and Event
Management (SIEM) that improves internal network
security and helps to comply with the latest IT audit
requirements.
In most of the enterprise organizations, all the servers are
installed and configured with anti-virus, anti-spam and
anti-spyware software, hence it would be difficult to trace
out the occurrence of a particular event in the huge
volume of log file. So the analysis software should consist
of a central syslog server, log rotation scripts, data
filtration and categorization programs, command line or
web utilities to perform queries against the data and
generate reports. The Figure (Fig – 5) shows the
architecture of typical log data analysis and management
software. It is consists of 3 layers as described in the
following table (Table -1),
Table – 1: Layers of Log Analyzer Software
S.No.

Layers

Description

1.

Layer1

Log data fetching from servers and
rotation using script program

2.

Layer2

Meta data analysis, categorization
and storage of log data in Database

3.

Layer3

Querying and Report generation

In layer one, the script program fetches the log data,
rotates it and store the raw log data in a file. This file is
further analyzed and checked for consistency. In layer two,
one more script program will categorize the data
according to the organization policy and splits the data
using the unique identifier of log and sends it to the
database. In layer three, web utility programs are used for
querying and generating the customized reports.

© 2015, IRJET.NET- All Rights Reserved

Fig-5: Log data analysis and management software
architecture
8. REPORT GENERATION
The raw data collected from all the servers is converted
into meaningful log data according to the organization’s
event management. This log data can be filtered based on
various criteria and the reports can be scheduled as and
when required. The log analysis software offers highly

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flexible custom reports like Internet user activities,
intranet e-mail statistics, internet e-mail statistics, spam /
virus mail statistics, web access report, event severity,
event category and alert trend, current and historical
hourly
and
weekly
reports
etc.,

Same kind of reports can be generated for Web servers,
proxy servers, firewall servers, etc., The raw data of all the
servers thereby classified and demystified using the
indigenous, in-house developed software solution. This
helps the administrator to monitor all the internet /
intranet user activities and generate reports by sitting in a
centralized location.
9. CONCLUSION
Organizations need to monitor all the activities happening
in their network and accesses to sensitive data, regardless
of their security policy imposed. Sensitive data resides on
core applications such as web applications / e-mail should
be monitored primarily through the analysis of the logs.
These data are highly complex and adherence to
compliance mandates requires a robust log analysis
solution that can accommodate the speed and complexity
of these sources for immediate alerting as well as longterm reporting. Thus the efficient event log analysis or
syslog analysis solves the data management problems,
reduces
system
downtime,
increases
network
performance, and helps tighten security policies of the
enterprise.

REFERENCES

Fig – 6: Report generated using in-house developed e-mail
log analysis software
Reports are displayed in both graph and table formats,
reports can be configured for working and non-working
hours, Reports can be filtered for individual severity and
category. The figure (Fig-6) shows the report generated
against the requirement of IT Manager / system
administrator for e-mail server:
© 2015, IRJET.NET- All Rights Reserved

[1] E-Mail auditing, logging and reporting, White paper –
Sendmail Inc, 2007
[2] E-Mail Data-Mining: An Approach to construct an
Organization position-wise structure while performing
E-Mail Analysis, Bhargav vadher, San Jose State
University, 1-1-2010
[3] National Institute of standards and technology, ITL
Bulletin, U.S. Department of Commerce, January,
N2003
[4] SANS Institute Info Sec Reading Room, Log Analyzer for
Dummies, December 10, 2007
[5] Log message classification with syslog-ng,
www.balabit.com, 18, January, 2011
[6] Understanding Syslog: Servers, Messages & Security,
AaronLeskiw,http://www.Networkmanagement
software.com, 2011
[7] Kaspersky-Web-Mail-Server-Best-Practice-Guide,
Kaspersky Lab ZAO, 2012
[8] SANS Information System Audit Logging Requirements
(2006)
[9] NIST Information System Audit Logging Requirements
(2006)
[10] Distributed syslog architectures with syslog-ng
Premium Edition (2008)
[11] Archiving For Linux / Unix Systems & Syslog
Supported Devices
[12] Central Log Server – Why and How, Cyber Diligence,
July-September, 2013
[13] haradchhetri.com/2014/03/01/install-and-

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configure-rsyslog-on-rhel-6-centos-6/

BIOGRAPHIES
R.Anusooya received her B.E
Degree from Madras University,
T.N in 1997. She joined in Indira
Gandhi Centre for Atomic
Research (IGCAR) in 2001. She
did her M.Tech in Sathyabama
University in 2013. She is
currently a Scientific Officer-E in
Electronics, Instrumentation and
Radiological Safety Group-IGCAR.
She has 8 Journal Publications /
Conference Papers and 10
Internal Design Reports.
J. Rajan did his B.E. (ECE) from
Madras University (1992) & M.S
(Software Systems) from BITS,
Pilani
(1999).
He
joined
Computer Division, Indira Gandhi
Centre for Atomic Research in
1999. He is presently functioning
as the head of Networking
Section (Computer Division) of
Indira Gandhi Centre for Atomic
Research. He is specialized in the
areas of Computer Networks,
Information Security and 3D
Visualization.

S.A.V Satya Murty received his
BTech Degree from Jawaharlal
Nehru Technological University,
A.P in 1977. Later, he joined one
year orientation course in
Nuclear Science & Engineering
(21st Batch) at Bhaba Atomic
Research Centre,Mumbai and
then he joined in Indira Gandhi
Centre for Atomic Research
(IGCAR) in 1978. He is currently
an Outstanding Scientist, Director
of Electronics, Instrumentation
and Radiological Safety GroupIGCAR. He has 110 Journal
Publications / Conference Papers,
40 Internal Design Reports and
edited
two
International
Conference Proceedings.

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