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Network+ > Network Management Services > Flashcards

Network Management Services Flashcards

1
Q

SSH

A

Secure Shell

  • Principal means of secure remote access to UNIX and Linux servers and most types of network appliances
  • Can be used to secure SFTP
  • Port 22 by default
  • Server must be configured with key pair, but client can use key pair or other authentication method, like a password
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2
Q

SSH Host Key

A
  • Public/private key pair that identifies SSH server
  • Map of host names to public keys can be kept manually by each SSH client
  • Must be changed if any compromise of host is suspected, as the attacked could masquerade as the server
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3
Q

SSH Client Authentication Kerberos

A
  • Client submits Kerberos credentials obtained when user logged into workstation to the server using the generic Security Services Application Program Interface (GSSAPI)
  • Server contacts ticket Granting Service(often DC) to validate credential
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4
Q

SSHD

A
  • Starts SSH Daemon

- Parameters like host’s certificate file, port to listen on and logging options can be set

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5
Q

ssh-keygen

A
  • Create a key pair to access servers
  • Private key must be stored securely on local computer
  • Public key must be copied to server
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6
Q

ssh-agent

A
  • Configure service to use to store the keys used to access multiple hosts.
  • Reduces the number of times key must be confirmed with passphrase
  • Provides SSO mechanism for multiple SSH servers
  • SSH-ADD used to add key to agent
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7
Q

ssh host

A

Use SSH Client to connect to the server running host.

- host can be FQDN or IP address

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8
Q

ssh Username@host

A
  • Use SSH client to connect to server running at host with a different username
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9
Q

SNMP

A

Simple Network Management Protocol

  • Widely used framework for remote management and monitoring of servers and network appliances
  • Uses agents and a monitoring system
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10
Q

SNMP Agents

A
  • Process running on network device or server
  • Maintains database of statistics relating to activity of device called MIB (Management Information Base)
  • Each parameter in MIB is call OID(Object Identifier)
  • Passes information top management system, with same community name
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11
Q

SNMP Monitor

A
  • Management system where you can oversee network activity
  • Polls agents at intervals for MIBs
  • Gets information by “Get” regular polling
    or Trap, based on certain threshold meeting events
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12
Q

Syslog

A
  • protocol and supporting software that facilitates log collection
  • De facto standard for logging events from distributed systems
  • Usually listens on port 514
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13
Q

Logging level

A
  • Determines maximum level at which events are recorded or forwarded
  • 0 is highest priority
  • If it is set to 4, levels 5-7 are not forwarded
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14
Q

Jitter

A
  • Variation in transmission delay

- Mainly a problem for real-time applications

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15
Q

Diffserv

A

Differentiated Services

  • Classifies each packet passing through a device
  • Policies can be applied to router to prioritize delivery
  • Works at layer-3
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16
Q

Traffic Shapers

A
  • delay certain packet types based on content to ensure other packets have priority
  • Helps reduce latency for critical services
  • Stores packet until there is bandwidth available
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17
Q

Top Talker/Listener

A
  • Interfaces generating most outgoing traffic(in terms of bandwidth)
  • Listeners receive most traffic
  • Identifying these and routes can be useful to eliminate bottlenecks
18
Q

Netflow

A
  • Gathers traffic metadata only and reports to structured database
  • Use sapling to reduce processing demands
  • Utilizes exporters, collectors and analyzers
19
Q

Link State

A
  • Whether or not an interface is up or down
  • Alerts can be configured for when an interface goes down
  • You can also track downtime percentage
20
Q

Reset

A
  • Number of times an interface has restarted in sample time.
  • If interface is continually resetting it is described as flapping
21
Q

Speed

A
  • rated speed of interface in Mbps or Gbps

- Should be the same for host and switch ports

22
Q

Duplex

A
  • Most ethernet interfaces operate in full duplex

- If operating in half, indicates a problem

23
Q

Utilization

A
  • Data transferred over a period of time

- calculated as amount transferred or as % of available bandwidth

24
Q

Per-Protocol Untilization

A
  • Packet or byte count for a specific protocol
25
Q

Error Rate

A
  • Number of packets per second that cause errors

- May be caused from interference or bad link quality

26
Q

Discard and drops

A
  • Interface may discard frames for reasons like checksum errors, mismatched MTUs, too small packets (runts) to big (giants).
27
Q

Retransmissions

A
  • Caused by packet loss necessitating retransmission
28
Q

CRC

A

Cyclic Redundancy Check

  • Calculated by an interface when it sends a frame
  • Derives a 32 bit value from contents of fram
  • Added to header
  • Receiving interface runs same calculation and rejects different value
  • Errors caused by interference on Layer 1
29
Q

Public Key Management

A
  • Critical security task
  • If a users private key is compromised, public key must be deleted and regenerated
  • Always delete public keys if user access had been revoked
30
Q

System Log

A
  • Records Startup events and subsequent changes to configuration at OS level
  • Includes Kernel Processes and drivers but also core services
31
Q

Application Log

A
  • Records data for single, specific service like DNS, HTTP or RDBMS
  • Complex application could write multiple log files
32
Q

Audit Logs

A
  • Records use of authentication and authorization privileges
  • Generally records success/fail type events
  • Also called access or security log
  • Done at OS level or per application level
33
Q

Performance/Traffic Logs

A
  • Record statistics for compute, storage and network resources over defines period
34
Q

Latency

A
  • Time it takes for transmission to reach recipient
  • Measures in ms
  • Problem for real time applications
  • Can test with ping, pathping and mtr
  • Need to consider RTT(Round Trip Time)
  • VoIP RTT is required to have less than 300 ms.
35
Q

802.1p

A
  • Used at layer 2 to classify and prioritize traffic passing through switch or WAP
  • Defines tagging mechanism in VLAN field (802.1Q/p)
  • Value is set to 0-7, with 0 being highest priority
36
Q

Class of Service Mechanisms

A
  • Categorize protocols into groups that require different service levels and provide tagging mechanism to identify them
  • DiffServ and 802.1p
37
Q

Control Plane

A
  • Division of network function for QoS

- Makes decisions about how traffic should be prioritized and where it should be switched

38
Q

Data Plane

A
  • Division of network function for QoS

- Handles actual switching of traffic

39
Q

Management Plane

A
  • Division of network function for QoS

- Monitors traffic conditions

40
Q

Traffic Shapers

A
  • Delay certain packet types based on their content

- Will store packets until bandwidth is available

41
Q

Throughput testers

A
  • Divides file size by time it took to transfer file
  • Should be used at a time representative of real-world network usage
  • iperf, ttcp, bwping can be used as throughput testers
42
Q

Encapsulation Errors

A
  • Error in the frame format expected by the interface
  • Prevents transmission and reception
  • Physical link will appear as up, but line protocol will be listed as down
    Issue could be:
  • Wrong frame type
  • Ethernet trunk error
  • Router framing

Network+ (36 decks)

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