Network Security Model - Defining an Enterprise Security Strategy

Overviewauthentication and authorization
These are the 5 primary security groups that should· Unix and Mainframe host authentication and
be considered with any enterprise security model.authorization
These include security policy, perimeter, network,· Application authorization per server
transaction and monitoring security. These are all part· File and data authorization
of any effective company security strategy. AnyTransaction Security
enterprise network has a perimeter that represents allTransaction security works from a dynamic
equipment and circuits that connect to externalperspective. It attempts to secure each session with
networks both public and private. The internal networkfive primary activities. They are non-repudiation,
is comprised of all the servers, applications, data, andintegrity, authentication, confidentiality and virus
devices used for company operations. Thedetection. Transaction security ensures that session
demilitarized zone (DMZ) represents a locationdata is secure before being transported across the
between the internal network and the perimeterenterprise or Internet. This is important when dealing
comprised of firewalls and public servers. It that allowswith the Internet since data is vulnerable to those that
some access for external users to those networkwould use the valuable information without permission.
servers and denies traffic that would get to internalE-Commerce employs some industry standards such
servers. That doesn't mean that all external users willas SET and SSL, which describe a set of protocols
be denied access to internal networks. On thethat provide non-repudiation, integrity, authentication and
contrary, a proper security strategy specifies who canconfidentiality. As well virus detection provides
access what and from where. For instancetransaction security by examining data files for signs of
telecommuters will use VPN concentrators at thevirus infection before they are transported to an
perimeter to access Windows and Unix servers. Asinternal user or before they are sent across the
well business partners could use an Extranet VPNInternet. The following describes industry standard
connection for access to the company S/390transaction security protocols.
Mainframe. Define what security is required at allNon-Repudiation - RSA Digital Signatures
servers to protect company applications and files.Integrity - MD5 Route Authentication
Identify transaction protocols required to secure dataAuthentication - Digital Certificates
as it travels across secure and non-secure networkConfidentiality - IPSec/IKE/3DES
segments. Monitoring activities should then be definedVirus Detection - McAfee/Norton Antivirus Software
that examine packets in real time as a defensive andMonitoring Security
pro-active strategy for protecting against internal andMonitoring network traffic for security attacks,
external attacks. A recent survey revealed thatvulnerabilities and unusual events is essential for any
internal attacks from disgruntled employees andsecurity strategy. This assessment identifies what
consultants are more prevalent than hacker attacks.strategies and applications are being employed. The
Virus detection should then be addressed sincefollowing is a list that describes some typical monitoring
allowed sessions could be carrying a virus at thesolutions. Intrusion detection sensors are available for
application layer with an e-mail or a file transfer.monitoring real time traffic as it arrives at your
Security Policy Documentperimeter. IBM Internet Security Scanner is an excellent
The security policy document describes variousvulnerability assessment testing tool that should be
policies for all employees that use the enterpriseconsidered for your organization. Syslog server
network. It specifies what an employee is permitted tomessaging is a standard Unix program found at many
do and with what resources. The policy includescompanies that writes security events to a log file for
non-employees as well such as consultants, businessexamination. It is important to have audit trails to record
partners, clients and terminated employees. In additionnetwork changes and assist with isolating security
security policies are defined for Internet e-mail andissues. Big companies that utilize a lot of analog dial
virus detection. It defines what cyclical process if any islines for modems sometimes employ dial scanners to
used for examining and improving security.determine open lines that could be exploited by
Perimeter Securitysecurity hackers. Facilities security is typical badge
This describes a first line of defense that externalaccess to equipment and servers that host mission
users must deal with before authenticating to thecritical data. Badge access systems record the date
network. It is security for traffic whose source andtime that each specific employee entered the telecom
destination is an external network. Many componentsroom and left. Cameras sometimes record what
are used to secure the perimeter of a network. Thespecific activities were conducted as well.
assessment reviews all perimeter devices currentlyIntrusion Prevention Sensors (IPS)
utilized. Typical perimeter devices are firewalls, externalCisco markets intrusion prevention sensors (IPS) to
routers, TACACS servers, RADIUS servers, dialenterprise clients for improving the security posture of
servers, VPN concentrators and modems.the company network. Cisco IPS 4200 series utilize
Network Securitysensors at strategic locations on the inside and outside
This is defined as all of the server and legacy hostnetwork protecting switches, routers and servers from
security that is implemented for authenticating andhackers. IPS sensors will examine network traffic real
authorizing internal and external employees. When atime or inline, comparing packets with pre-defined
user has been authenticated through perimetersignatures. If the sensor detects suspicious behavior it
security, it is the security that must be dealt withwill send an alarm, drop the packet and take some
before starting any applications. The network exists toevasive action to counter the attack. The IPS sensor
carry traffic between workstations and networkcan be deployed inline IPS, IDS where traffic doesn't
applications. Network applications are implemented onflow through device or a hybrid device. Most sensors
a shared server that could be running an operatinginside the data center network will be designated IPS
system such as Windows, Unix or Mainframe MVS. Itmode with its dynamic security features thwarting
is the responsibility of the operating system to storeattacks as soon as they occur. Note that IOS intrusion
data, respond to requests for data and maintainprevention software is available today with routers as
security for that data. Once a user is authenticated toan option.
a Windows ADS domain with a specific user account,Vulnerability Assessment Testing (VAST)
they have privileges that have been granted to thatIBM Internet Security Scanner (ISS) is a vulnerability
account. Such privileges would be to access specificassessment scanner focused on enterprise customers
directories at one or many servers, start applications,for assessing network vulnerabilities from an external
and administer some or all of the Windows servers.and internal perspective. The software runs on agents
When the user authenticates to the Windows Activeand scans various network devices and servers for
Directory Services distributed it is not any specificknown security holes and potential vulnerabilities. The
server. There is tremendous management andprocess is comprised of network discovery, data
availability advantages to that since all accounts arecollection, analysis and reports. Data is collected from
managed from a centralized perspective and securityrouters, switches, servers, firewalls, workstations,
database copies are maintained at various serversoperating systems and network services. Potential
across the network. Unix and Mainframe hosts willvulnerabilities are verified through non-destructive
usually require logon to a specific system, however thetesting and recommendations made for correcting any
network rights could be distributed to many hosts.security problems. There is a reporting facility available
· Network operating system domainwith the scanner that presents the information findings
authentication and authorizationto company staff.
· Windows Active Directory Services