WAN CH 4 Security

7/30/2019 WAN CH 4 Security

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CCNA4-1 Chapter 4-1

Chapter 4

Network Security


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CCNA4-2 Chapter 4-1

Introducing Network Security


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CCNA4-3 Chapter 4-1


Increasing Threat to Security: Over the years, attack tools have evolved.


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CCNA4-4 Chapter 4-1


Common Terms: White Hat:

An individual who looks for vulnerabilities in systems and reports

these so that they can be fixed.

Black Hat:

An individual who uses their knowledge to break into systems that

they are not authorized to use.

Hacker:

A general term that has historically been used to describe a computerprogramming expert.


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CCNA4-5 Chapter 4-1

Common Terms: Network Security

Cracker:

Someone who tries to gain unauthorized access to network resources

with malicious intent.

Phreaker:

Individual who manipulates phone network, through a payphone, to make

free long distance calls.

Spammer:

An individual who sends large quantities of unsolicited e-mail messages.

Phisher: Uses e-mail or other means to trick others into providing information.


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CCNA4-6 Chapter 4-1

Types of Computer Crime:

Most commonly reported acts of computer crime fall into four generalcategories, or a combination thereof, that effective and vigilant security

management can address.

Insider Abuse

Denial of Service

System Penetration

Password sniffing


7/88CCNA4-7 Chapter 4-1

Open versus Closed Networks:

The challenge is to find the correct balance.

Networks must be accessible to be of any use.

Networks must be secure to protect corporate and personal information.



FIRST STEP: Developing a Security Policy

A Security Policy meets these goals:

1. Informs users, staff, and managers of their requirements for protecting

information assets.

Addresses both acceptable and unacceptable use.

2. Specifies the mechanisms through which these requirements can be

met.

Managing security violations.

3. Provides a baseline to acquire, configure, and audit computer systems

for compliance.

Basis for legal action.



The Enterprise Security Policy

A living document: The document is never finished and is continuously updated as

technology and employee requirements change.

Essential Functions:

Protects people and information.

Sets the rules for expected behavior by users, system administrators,

management, and security personnel.

Authorizes security personnel to monitor, probe, and investigate.

Defines and authorizes the consequences of violations.



The Enterprise Security Policy

Attributes:1. Provides a means to audit existing network security and compare the

requirements to what is in place.

2. Plan security improvements, including equipment, software, and

procedures.

3. Defines the roles and responsibilities of the company executives,

administrators, and users.

4. Defines which behavior is and is not allowed.

5. Defines a process for handling network security incidents.

6. Enables global security implementation and enforcement by acting as astandard between sites.

7. Creates a basis for legal action if necessary.



Common Security Threats

Three common factors - Network Security:

Vulnerability: The degree of weakness which is inherent in every network

and device.

Routers, switches, desktops, and servers.

Threats: The people interested in taking advantage of each security

weakness.

Attack: Variety of tools and programs to launch attacks against networks.



Three Primary Vulnerabilities:

1. Technological weaknesses. Computer and network technologies have intrinsic security

weaknesses.




2.Configuration weaknesses

Network administrators need to learn what their network

configuration weaknesses are

Correctly configure their computing and network devices to

compensate.




Physical Threats - Four classes:1. Hardware Threat:

Physical damage to servers, routers, switches, cabling plant, and

workstations.

Security Measures:

Lock up equipment and prevent

unauthorized access.

Monitor wiring closet

access electronic logs. Security cameras


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CCNA4-15 Chapter 4-1

Threats to Physical Infrastructure

2. Environmental Threat: Temperature or humidity extremes.

Security Measures:

Temperature control. Humidity control.

Positive air flow.

Remote environment alarms.


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3. Electrical Threat: Voltage spikes, insufficient voltage (brownouts), unconditioned power

(noise), and total power loss.

Security Measures:

UPS systems

Generators

Preventive maintenance

Redundant power supply

Remote alarms


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4. Maintenance: Poor handling of key electrical components, lack of critical spare

parts, poor cabling, and poor labeling.

Security Measures:

Neat cable runs

Label the cables

Electrostatic discharge procedures

Stock critical spares

Control console port access


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You probably want to avoid this


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Threats to Networks

Network Threats:

Inexperienced individuals

with easily availablehacking tools.

Groups or individuals

highly motivated and

technically competent.

Individuals or groups

outside the company.

Authorized access or

physical access to

the network.


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Social Engineering

The easiest hack involves no computer skill. If an intruder can trick a member of an organization into giving over

information, such as the location of files or passwords, the process of

hacking is made much easier.

Phishing: A type of social engineering attack that involves using

e-mail in an attempt to trick others into providing sensitive

information, such as credit card numbers or passwords.

Phishing can be prevented by educating users and implementingreporting guidelines when they receive suspicious e-mail.


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Types of Network Attacks

Four primary classes of Attacks: Reconnaissance

Access

Denial of Service

Malicious Code


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Reconnaissance:

Reconnaissance - the unauthorized discovery and mapping of systems,services, or vulnerabilities.

In most cases, this precedes another type of attack.

Can consist of:

1. Internet Information Queries

2. Ping Sweeps

3. Port Scans

4. Packet Sniffers


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System Access

System access - the ability of an intruder to gain access to a devicefor which the intruder does not have an account or a password.

Usually involves running a hack, script, or tool that exploits a known

vulnerability of the system or application being attacked.


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Denial of Service:

Denial of Service (DoS) - when an attacker disables or corrupts networks,systems, or services with the intent to deny services to intended users.

DoS attacks involve either crashing the system or slowing it down to the

point that it is unusable.

DoS -- MOST FEARED!

W Vi d


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Worms, Viruses and

Trojan Horses:

Malicious software can be inserted onto a host to damage or corrupt asystem, replicate itself, or deny access to networks, systems, or

services.


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Internet Queries:

External attackers can use Internet tools, such as the nslookup andwhois utilities, to easily determine the IP address space assigned to a

given corporation or entity.


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Ping Sweeps:

After the IP address space is determined, an attacker can then ping thepublicly available IP addresses to identify the addresses that are active.

To help automate this step, an attacker may use a ping sweep tool, such

as fping or gping.


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Port Scans:

After identifying the active IP addresses, the intruder uses aport scanner to determine which network services or ports are

active on the live IP addresses.

A port scanner is software, such as Nmap or Superscan, that is

designed to search a network host for open ports.


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Packet Sniffers:

Internal attackers may attempt to "eavesdrop on network traffic.

Wire Shark can be used for this

Two common uses of eavesdropping are:

1. Information Gathering

2. Information Theft


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Packet Sniffers:

A common method for eavesdropping is to capture TCP/IP or other protocolpackets and decode the contents.

Methods for counteracting eavesdropping are:

1. Using switched networks instead of hubs so that traffic is not broadcast to

all endpoints or network hosts.

2. Using encryption that meets the data security needs without imposing an

excessive burden on system resources or users.

3. Forbid the use of protocols with known susceptibilities to eavesdropping.

(e.g. SNMP vs SNMP v3)


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Types of Network Attacks

Access Attacks: Access attacks exploit vulnerabilities in authentication, FTP, and web

to gain entry to accounts, confidential, and sensitive information.

The more common are:

Password Attacks

Trust Exploitation

Port Redirection

Man-in-the-Middle


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General Mitigation Techniques

Device Hardening:1. Default usernames and passwords should be changed.

2. Access to system resources should be restricted to only the

individuals that are authorized.

3. Any unnecessary services should be turned off.

Antivirus Software

Personal Firewalls

OS Patches


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General Mitigation Techniques

A Firewall by itself is no longer adequate for securing a network.

An Integrated Approach with a firewall, intrusion prevention, and VPN.

Follows these building blocks:

1. Threat Control: Regulates network access, prevents intrusions, by

counteracting malicious traffic.

2. Secure Communications: Secures network endpoints with a VPN.

3. Network Admission Control (NAC): Provides a roles-based method of

preventing unauthorized access.


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The Network Security Wheel


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The Role ofRouters in Network Security:

Router security is a critical element in any security deployment becauserouters are definite targets for network attackers.

Roles of the Router in Network Security:

1. Advertise networks and filter who can use them.

2. Provide access to network segments and subnetworks.


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Router Security Issues

1. Compromising the access control can expose network configurationdetails, thereby facilitating attacks against other network components.

2. Compromising the route tables can reduce performance, deny network

communication services, and expose sensitive data.

3. Misconfiguring a router traffic filtercan expose internal networkcomponents to scans and attacks, making it easier for attackers to avoid

detection.


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Securing routers at the network perimeteris an important first step insecuring the network.


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Physical: Locate the router in a

locked room that is accessible

only to authorized personnel.

UPS.

Updating the Router IOS:

The latest version of an operating system may not be the most stable

version available.

Use the latest, stable release that meets the feature requirements of

your network.


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Configuration and IOS: Keep a secure copy of the router

IOS and router configuration file

on a TFTP server for backup

purposes.

Unused Services:A router has many services enabled by default.

Harden your router configuration by disabling unnecessary services and

unused ports.


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Applying Cisco IOS Security Features

Steps to safeguard a router:


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Step 1: Configuring passwords

A strong password is the most fundamental element in controlling secureaccess to a router.

Follow accepted password practices.

Dont write it down.

Avoid dictionary words.

Combine letters, numbers and symbols.

Make password lengthy.

Change passwords frequently.

The commandno passwordon vty lines prevents any login.


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Step 1: Configuring passwords

By default, Cisco IOS software leaves passwords in plain text

when they are entered on a router.

service password-encryption

enable secret 2ManY-routEs

security passwords min-length 10

S S


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Step 2: Secure Remote Administrative Access

Local access through the console port is the preferred way for anadministrator to connect to a device to manage it because it is secure.

Remote administrative access is more convenient than local access.

Using Telnet can be very insecure because all network traffic is in plaintext.

An attacker could capture network traffic and sniff the administratorpasswords or router configuration.

S 2 S R Ad i i i A


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Remote access typically involves allowing Telnet, Secure Shell (SSH),HTTP, HTTP Secure (HTTPS), or SNMP connections to the router from a

computer.

1. Establish a dedicated management network.

2. Secure the administrative lines.

3. Encrypt all traffic between the

administrators computer and

the router.

St 2 S R t Ad i i t ti A


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1. Logins may be prevented on any line by configuring the router with thelogin and no password commands.

2. VTY lines should be configured to accept connections only with theprotocols actually needed.

transport input telnet only telnet

transport input telnet ssh telnet or ssh

3. Implement Access Control Lists (ACLs)

4. Configure VTY timeouts using the exec-timeout command.

C fi i SSH S it


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Configuring SSH Security

To enable SSH, the following parameters must be configured:

Hostname

Domain Name

Asymmetrical Keys

Local Authentication

C fi i SSH S it


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Step 1: Hostname:

Step 2: Domain Name: Required for SSH.

C fi i SSH S it


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Step 3: Generate the RSA key:This step creates an asymmetrical key that router uses to encrypt the SSH

management traffic.

Cisco recommends a modulus length of1024. A longer length

generates a more secure key but adds some latency.

C fi i SSH S it


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Step 4: Configure local authentication and vty: You must define a local user.

Use the login local command to search the localdatabase and assign ssh to the vty lines.

Makes SSH the

only method.

NO TELNET

C fi i SSH S it


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Step 5: Configure SSH timeouts:

Not absolutely necessary for SSH but probably a good idea.

T t SSH S it


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Test SSH Security

To connect to a router configured with SSH, you have to use an SSH clientapplication such as PuTTY orTeraTerm.

Choose the SSH option and use TCP port 22.

Step 3: Log Router Activity


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Step 3: Log Router Activity

Logs allow you to verify router is working properly. Routers support 8 levels of logging.

The most important thing to remember about logging is that logs

must be reviewed regularly.

0: Emergencies

1: Alerts

2: Critical

3: Errors

4: Warnings

5: Notification6: Informational

7: Debugging

Step 4 Sec ring Ro ter Net ork Ser ices


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Step 4: Securing Router Network Services

Cisco routers support network services at Layers 2, 3, 4, and 7. Some of them areApplication Layer protocols.

Others are automatic processes and settings intended to support legacy

configurations that pose security risks.

Some of these services can be restricted or disabled to improve securitywithout degrading the operational use of the router.

Most of the services listed in this section are usually not required.

Manage Router Security


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Turning off a service on the router itself does not mean thatthe service or protocol cannot be used on the network.

For example:

TFTP (Trivial File Transfer Protocol)

DHCP (Dynamic Host Configuration Protocol)

Turning off an automatic network feature usually prevents a

certain type of network traffic.

For example:

IP Source Routing is rarely used but can be used in

network attacks.



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SNMP (Simple Network Management Protocol):

1. SNMP is the standard Internet protocol for automated remote monitoringand administration.

2. Versions of SNMP prior to Version 3 shuttle information in clear text.

NTP (Network Time Protocol): Cisco routers and other hosts use NTP to keep their time-of-day clocks accurate.

Network administrators should configure all routers as part of an NTP hierarchy.

One Router is the Master Timer--provides its time to other routers on the

network.

If an NTP hierarchy is not available on the network, you should disable NTP.



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DNS (Domain Name System):

Cisco IOS software supports looking up hostnames with the Domain

Name System (DNS).

The basic DNS protocol offers no authentication orintegrity assurance.

By default, name queries are sent to broadcast address 255.255.255.255.

1. Explicitly set the name server addresses using the global configurationcommand ip name-server addresses

OR

2. Turn off DNS name resolution with no ip domain-lookup command.

Step 5: Securing Routing Protocols


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Routing systems can be attacked in 2 ways:

Disruption of peers:

It is the less critical of the two attacks because routing protocols heal

themselves.

Falsification of routing information:

Falsified routing information may generally be used to cause systems to

misinform (lie to) each other, cause a DoS, or cause traffic to follow a

path it would not normally follow.



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RIPv2, EIGRP, OSPF, IS-IS, and BGP all support various forms of MD5

authentication.

1.Prevent RIP updates from being propagated out ports where there is no other

router.

passive interface command.

2.Prevent unauthorized reception of RIP updates by implementing MD5

authentication with a specific key.

3.Verify RIP routing.

While the commands are different, the same basic process is used for other

protocols.

Locking Down Your Router With Cisco Auto Secure:


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Locking Down Your Router With Cisco Auto Secure:

Cisco AutoSecure uses a single command to disable non-essential system

processes and services.

Configure it in privileged EXEC mode using the auto secure command in

one of these two modes:

Interactive mode:

This mode prompts you with options to enable and disable

services and other security features. (default)

Non-interactive mode: Automatically executes the auto secure command with the

recommended Cisco default settings.

Using Cisco SDM (CCNA test questions)


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Cisco SDM Overview: The Cisco Security Device Manager (SDM) is a web-based device

management tool designed for configuring LAN, WAN, and security

features on Cisco IOS software-based routers.

It provides:

Easy-to-use smart wizards. Automates router security management.

Assists through comprehensive online help.

SDM files can be installed on router, PC, or both. An advantage of installing SDM on the PC is that it saves router

memory, and allows you to use SDM to manage other routers on the

network.

Cisco Configuration Professional (CCP)


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Replacing SDM

Cisco Configuration Professional is a GUI based device management tool for Cisco access

routers.

It simplifies Router, firewall, IPS, VPN, unified communications, WAN, LAN and basic

wireless configuration through easy-to-use wizards.

CCP is a valuable productivity-enhancing tool for network administrators and channel

partners for deploying routers in medium-sized businesses and enterprise branch offices

with increased confidence and ease.

CCP has configuration checks built into the application thereby reducing errors.

The new device manager for Cisco integrated services routers, CCP will replace Cisco

Router and Security Device Manager (SDM) over time.

Like SDM, Cisco Configuration Professional assumes a general understanding of

networking technologies and terms but assists individuals unfamiliar with the Cisco CLI.

http://www.cisco.com/go/ciscocp

Maintaining Cisco IOS Software Images


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There are certain guidelines that you must follow when changing the Cisco

IOS software on a router.

Updates:

A free update replaces one release with another without upgrading

the feature set. (Bug fixes)

Upgrades:

An upgrade replaces a release with one that has an upgraded

feature set or new technologies.

Upgrades are not free.



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It may not be a good idea to upgrade to the latest version of IOS software.

Many times that release is not stable.

It may include new features or technologies that are not needed in your

enterprise.



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Cisco recommends a four-phase migration process.

1. Plan:

Set goals, identify resources, profile network hardware and software,

and create a schedule for migrating to new releases.

2. Design: Choose new Cisco IOS releases.

3. Implement:

Schedule and execute the migration.

4. Operate: Monitor the migration progress and make backup copies of images

that are running on your network.



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Tools available on Cisco.com to aid in migrating Cisco IOS software.

Some tools do not require a Cisco.com login:

Cisco IOS Reference Guide.

Cisco IOS software technical documents.

Cisco Feature Navigator

Some tools require valid Cisco.com login accounts:

Download Software.

Bug Toolkit.

Software Advisor. Cisco IOS Upgrade Planner.

http://www.cisco.com/en/US/support/tsd_most_requested_tools.html

Managing Cisco IOS Images


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Cisco IOS File Systems and Devices: Integrated File System (IFS)

The directories available depend on the platform

The show file systems command lists all file systems.

It provides information such as the amount of available and free memory,

type of file system and its permissions.

Permissions include read only (ro), write only (wo), and read and write

(rw).



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Cisco IOS File Systems and Devices:

* = current default

# = bootable disk with

the current IOS file



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URL Prefixes for Cisco Devices: The copy command is used to move files from one

device to another, such as RAM, NVRAM, or a TFTP

server.

R2#copy run startR2#copy system:running-config nvram:startup-config

R2#copy run tftp:

R2#copy system:running-config tftp:

R2#copy tftp: start

R2#copy tftp: nvram:startup-config



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Cisco IOS File Naming Conventions: The IOS image file is based on a special naming convention that

contains multiple parts, each with a specific meaning.

TFTP Managed Cisco IOS Images


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For any network, it is always prudent to retain a backup copy of the IOS

image in case the image in the router becomes corrupted or accidentally

erased.

Using a network TFTP server allows image and configuration

uploads anddownloads over

the network.

The TFTP server

can be anotherrouter or a

workstation.



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Before changing the

Cisco IOS image

complete these tasks:

1. Determine the memory required for the update.

2. Set up and test the file transfer capability.

3. Schedule the required downtime.



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When you are readyto do the update:

1. Shut down all interfaces not needed to perform the update.

2. Back up the current operating systemAND the current configuration file

to a TFTP server.

3. Load the update for either the operating system or the configuration file.

4. Test to confirm that the update works properly.



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Steps to copy flash to a TFTP server:

1. Ping the TFTP serverto make sure you have

access to it.

2. Verify that the TFTP serverhas sufficient disk

space.

3. Use the show flash:command to determine

the name of the files.

4. Copy the file(s) from the router to the TFTPserver using copy flash: tftp:command.

Each file requires a separate command.



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g C OS g

Upgrading a system to a newer software version requires a different

system image file to be loaded on the router.

Recovering IOS Software Images


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g g

When an IOS on a router is accidentally deleted from flash, the router is still

operational because the IOS is running in RAM.

It is crucial that the router is

not rebooted as a production device

since it would not be able to find avalid IOS in flash.

When the router is rebooted and can

no longer load an IOS it loads in

ROMmon mode by default.

prompt = rommon >



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g g

Using tftpdnld:

1. Connect a PC to the console port.

2. Connect the first Ethernet port

on the router to the TFTP

server with a cross-over cable.

3. Configure the TFTP server with a

static IP Address.

4. Boot the router and set the ROMmon variables.

5. Enter the tftpdnldcommand.



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g g

Case

Sensitive

Either power cycle the routeror use theresetcommand.



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g g

Using xmodem:

Connect a PC to the

console port.

Boot the router and

issue the xmodemcommand.



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g g

Using xmodem:

Load a terminal

emulation program

(Hyperterminal)

that supports the

Xmodem protocol.

Once the transfer has

finished, reboot

the router.

Troubleshooting Cisco IOS Configurations


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g g

Cisco IOS troubleshooting commands: show configured parameters and their values.

debug trace the execution of a process.

By default, the router sends the output from debug

commands to the console but it can be redirected to alogging server.

RouterPassword Recovery


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y

Recovering a password makes use of the routers configuration register.

This register is like the BIOS on a PC.

When a router boots, it will check the register and boot in the manner

specified by the value in the register.

For this course, we will only concern ourselves with two registry values.

0x2102: the default registry value.

0x2142: instructs the router to bypass any startup configuration.

RouterPassword Recovery Basic Steps:


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y p

1. Connect to the router console port.

2. Issue the show version command to obtain the current registry value.

RouterPassword Recovery Basic Steps


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1. Power cycle the router and press the Break key within 60 seconds.

This puts the router in ROMmon mode.

2. Type confreg 0x2142at the rommon 1 >prompt to specifybypassing the startup configuration.

3. Type reset or power cycle the router.

4. Bypass any default startup questions and type enable.

5. Copy the start up configuration to the running configuration

copy start run (reverse of what we normally do)

RouterPassword Recovery Basic Steps


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6. Change the password(s) to what you want them to be (enable secret,

Console or VTY)

7. Change the configuration registerback to the default using the

following command:

Router(config)#config-register 0x2102

8. Copy the running configuration to the startup configuration and reload or

power cycle the router.

copy run start (what we normally do)

WAN CH 4 Security

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