Cisco - Linux Commands on IOS

Today we’re going to go over a little known shell in IOS that gives us some bash like functionality! It is called IOS.sh

We can enable this little known functionality with the terminal shell command, like the rest of the terminal commands this only enables IOS.sh for the current terminal session.

R1#terminal shell

If you want to have the shell enabled permanently with the following global command

R1(config)#shell processing full

R1#show terminal | in Shell
Shell: enabled
Shell trace: off

Now IOS.sh is enabled! Awesome! But what does it do?
The simple answer is it makes IOS more like a Linux shell, it allows us to create variables, make loops, and use some linux utilities like grep or wc on the shell.

 

Using GREP

One of the neatest features of IOS.sh is the ability to use the grep utility to filter output. Let’s start by looking at the manpage for Grep, yes there are manpages!

R1#man grep
NAME
grep - get regular expression

SYNOPSIS
    grep [OPTIONS] <Regular Expression> [<file>...]

DESCRIPTION
    The 'grep' command matches lines in the given files
    with the supplied regular expression, and prints matching
    lines. There are lots of options
   
    -b              - match everything in a file after pattern
    -c              - print a count of lines instead of matched lines
    -e <pat>    - use &lt;pat&gt; as the pattern (it may have a leading minus)
    -h             - do not print filename for each match (default)
    -H             - print filename for each match
    -i              - ignore case
    -l              - print only files with match
    -L             - print only files without match
    -m            - match everything in a matching mode
    -n             - print line numbers along with matches
    -q             - quiet, only set status
    -s             - supress printing errors
    -u             - match everything in a file until pattern
    -v             - invert match, print non-matching lines

Part of the power of this command is because you can be more flexible than the standard include pipe command because you can do things like combine include and exclude like statements in the same line.

R1#show ip route | grep (150) | grep (10003)    
O        150.1.2.2 [110/10003] via 155.1.146.4, 15:51:41, GigabitEthernet1.146
O        150.1.3.3 [110/10003] via 155.1.146.4, 15:51:41, GigabitEthernet1.146
O IA     150.1.22.22 [110/10003] via 155.1.146.4, 1d11h, GigabitEthernet1.146

R1#show ip route | grep (150) | grep -v (10003)
      150.1.0.0/32 is subnetted, 11 subnets
C        150.1.1.1 is directly connected, Loopback0
O        150.1.4.4 [110/2] via 155.1.146.4, 15:51:57, GigabitEthernet1.146
O        150.1.5.5 [110/3] via 155.1.146.4, 15:51:57, GigabitEthernet1.146
O        150.1.6.6 [110/2] via 155.1.146.6, 1d12h, GigabitEthernet1.146
O IA     150.1.7.7 [110/3] via 155.1.146.6, 1d12h, GigabitEthernet1.146
O IA     150.1.8.8 [110/4] via 155.1.146.4, 15:52:07, GigabitEthernet1.146
O IA     150.1.9.9 [110/4] via 155.1.146.6, 1d12h, GigabitEthernet1.146
O IA     150.1.10.10 [110/5] via 155.1.146.4, 15:52:07, GigabitEthernet1.146

R1#show ip route | grep 150 | grep -v 10003 | grep 6\.6
O 150.1.6.6 [110/2] via 155.1.146.6, 00:35:18, GigabitEthernet1.146
O IA 150.1.7.7 [110/3] via 155.1.146.6, 00:35:08, GigabitEthernet1.146
O IA 150.1.9.9 [110/4] via 155.1.146.6, 00:35:08, GigabitEthernet1.146

 

WC

WC can be used to count the number of things in the output.

R1#man wc
NAME
    wc

SYNOPSIS
    wc [OPTION]... [FILE]...

DESCRIPTION
    Print newline, word, and byte counts for each FILE, and a total line if
    more than one FILE is specified. Read pipe input if no files are given
    -c print the byte counts
    -m print the character counts
    -l print the newline counts
    -L print the length of the longest line
    -w print the word counts

R1#show run | wc -l
216

 

Heads and Tails

These commands can be used to show the top x or bottom x lines of output, this can be handy with trying to see the latest logs.

R1#man head
NAME
    head - print the first lines in the input

SYNOPSIS
    head [<n>]

DESCRIPTION
    The 'head' program will print the first lines in
    its input. If given a numeric argument, it will
    print that many lines. The default number of lines
    is 10.

R1#man tail
NAME
    tail - print the last lines in the input

SYNOPSIS
    tail [<n>]

DESCRIPTION
    The 'tail' program will print the last lines
    in its input. If given a numeric argument, it
    will print that many lines. The default number
    of lines is 10.
    R1#

R1#show run | head 10
Building configuration...

Current configuration : 2844 bytes
!
! Last configuration change at 18:14:38 UTC Tue Nov 17 2015
!
version 15.5
no service timestamps debug uptime
no service timestamps log uptime
no platform punt-keepalive disable-kernel-core

R1#show run | tail 10
exec-timeout 0 0
privilege level 15
logging synchronous
stopbits 1
line vty 0 4
privilege level 15
no login
!
!
end

 

CAT

Ok fine, we can use the cat command to view text files on the Cisco device.

R1#man cat
NAME
    cat - write files or standard input to output

SYNOPSIS
    cat [<file>...]

DESCRIPTION
    The cat command writes whatever it sees to its output

    R1#copy running-config flash:cat.test
    Destination filename [cat.test]?
    2844 bytes copied in 0.463 secs (6143 bytes/sec)

R1#cat flash:cat.test
!
! Last configuration change at 18:14:38 UTC Tue Nov 17 2015
!
version 15.5
no service timestamps debug uptime
no service timestamps log uptime
no platform punt-keepalive disable-kernel-core
platform console serial

 

Variables

Lets start with making variables by first looking at the variables

R1#man variables
NAME
    variables - describe the usage of variables

DESCRIPTION
    Variables can be used in any context except single quotes. Variables
    can either be named, or numbered parameters to functions. Setting a
    named variable can be accomplished using an assignment statement.
    Assignment statments have a specific form, which is that the name of
    the variable must be immediately followed by an '=' sign. There can be
    no whitespace between the name and the '=':

    router> MYVAR='abc'

    The right side of the assignment is any string, but can also be the
    result of execution of a backquote expression, or the evaluation of a
    variable expansion.

    Variables may be used anywhere in subsequent input lines. One could,
    for example, create a shortcut for an interface name, and use it in
    config mode, or create a variable containing a number, and increment
    its value using arithmetic expression syntax (see man expressions).

    The main issue here is that the variable introduction character may
    conflict with existing usages, and so must be escaped in situations
    where a compatibility issue may arise. Please see man compatibility
    for more information.

To make a variable you simply have to enter VariableName=VariableValue

R1#VAR1=Value1
R1#VAR2=Value2

We can view the contents with the echo command

R1#echo $VAR1 $VAR2
Value1 Value2

You can also use variables in your commands

R2#var1=150.1.4.4

R2#ping $var1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 150.1.4.4, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 71/100/167 ms

 

Conditions and Loops

Following comparison operators can be used for working with integer values:
Operators   Characteristics
-eq               ==
-ne               !=
-lt                 <
-gt                >
-ge               >=
-le                =<

For working with files following conditions are available:

Operator    Characteristics
-a  or –e      True if file exists
-d               True if file exist and it is a directory
-f                True if file exists and is a regular file
-r                True if file exists and is readable
-s               True if file exists and has a size greater than zero
-w               True if file exists and is executable
-nt              Test if file1 is newer than file2. The modification date on the file is used for this comparison
-ot              Test if file1 is older than file2

Loops are very powerful (and dangerous if you don’t terminate them correctly) tools that allow you to carry out complex tasks.

R1#for x in 1 2 3 4 5 6 7 8 9
do..done>do
do..done>;ping 150.1.$x.$x
do..done>done

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 150.1.1.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 5/13/39 ms
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 150.1.2.2, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 64/140/228 ms
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 150.1.3.3, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 52/91/186 ms
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 150.1.4.4, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 31/61/117 ms
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 150.1.5.5, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 42/73/117 ms
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 150.1.6.6, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 34/51/93 ms
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 150.1.7.7, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 53/73/97 ms
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 150.1.8.8, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 67/98/116 ms
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 150.1.9.9, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 78/98/122 ms

 

Functions

Lastly for this blog entry, you can define functions to make repeated tasks easier.

R1#function test-r1() {
{..} >ping 150.1.4.4
{..} >}
R1#

R4#test-r1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 150.1.5.5, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 26/39/63 ms

You can see the functions defined on the system with show shell function

R4#show shell functions
User defined functions:

Function namespace: DEFAULT
    R1#function test-r1()
    {
     ping 150.1.5.5
    }

 

Taken From:

• https://www.reddit.com/r/ccie/comments/3t7s7h/bashing_cisco_playing_with_iossh/
• http://the-packet-thrower.com/2015/11/17/bashing-cisco-fun-with-ios-sh-2/#more-226

Networking - Structured Cabling

 

Structured Cabling

Although the physical layout of a network will to some extent be determined by its size and the type of networking technology chosen, the cabling system is a critical element of any network. It is generally accepted that a significant number of network failures are caused primarily by cable-related problems. Getting the cabling system right, therefore, is essential for an effective data communications system. With this need in mind, the development of industry standards for cabling standards has accompanied developments in network and communication technology. National and international telecommunications cabling standards have been widely adopted, all of which are based on the American ANSI/TIA/EIA cabling standards. The standards have been evolving since the mid-1980s, with the aim of creating a structured system for data communications cabling systems used in buildings that would support multi-vendor networking products and environments. The result was the TIA/EIA 568 Commercial Building Telecommunication Cabling standard, released in 1991. The ISO/IEC-11801 Generic Customer Premises Cabling standard is an international cabling standard based on the ANSI/TIA/EIA-568 cabling standard. Related European standards include EN 50173 and EN 50174.

The standards define how to design, build, and manage a cabling system that is structured, meaning that the system consists of a number of discrete sub-systems or blocks, each of which has specific performance characteristics. The blocks are organised hierarchically within a unified communication system. A workgroup LAN block, for example, has lower-performance requirements than a network backbone block, which usually requires high-performance fibre-optic cable. The standards have evolved to support high-speed networking technologies such as Gigabit Ethernet, and advanced cable types such as Category 6 and Category 7 twisted pair cable.

Structured cabling (sometimes referred to as premise wiring) defines a generic telecommunication wiring system for commercial buildings, and comprises the cabling, connectors and accessories used to connect local area network and telephone system equipment within a building. It breaks cabling systems down into two main elements, horizontal wiring and vertical (or backbone) wiring. Structured cabling standards define the media, topology, termination and connection points, and administrative practice to be used.
Some terms of reference are defined below:

• Horizontal wiring - all cabling between the telecommunications outlet in a work area and the horizontal cross-connect (also known as a floor distributor) in the telecommunications closet, including the telecommunications outlet itself, an optional consolidation point (or transition point) connector, and the horizontal cross-connect. Horizontal wiring, as the name suggests, usually runs horizontally (e.g. above suspended ceilings or below computer flooring) and does not go up or down between floors in a building. The maximum distance allowed between the telecommunications closet and the communication outlets is 90 metres, regardless of cable type. An additional 6 meters is allowed for patch cables at the telecommunication closet and in the work area, but the combined length of these patch cables cannot exceed 10 meters. The horizontal cable should be four-pair 100Ω UTP cable (the latest standards specify Category 5E as a minimum), two-fibre 62.5/125-mm fibre-optic cable, or 50/125-mm multimode fibre-optic cable.
• Vertical (or backbone) wiring - runs up through the floors of a building (risers) or across a campus, and is the cable used between telecommunications closets, entrance facilities, equipment rooms and buildings, including all cables, cable terminations, and intermediate and main cross connects. Backbone wiring runs between telecommunications closets, equipment rooms and entrance facilities on the same floor, from floor to floor, and even between buildings. The standards specify a hierarchical star topology for backbone cabling, in which all wiring radiates from a central location called a main cross-connect (usually the telecommunications closet). Each telecommunications closet or entrance facility is either cabled directly to the main cross-connect, or via intermediate cross connects. The distance limitations for this cabling depend on the type of cable used and the facilities it connects (twisted pair cable is limited to 90 meters).
• Work area - a building space in which operatives utilise telecommunications equipment. It includes all cable components between communication outlets (wall sockets) and end-user telecommunications equipment, such as telephones, workstations and printers, including the communication outlet itself. Work area cabling systems are designed to be flexible, but still require careful management. Standard structured cabling installation procedures should be observed when installing work area outlets, and cable terminations should be carried out using the same standard (T568A or T568B) throughout the system to avoid problems like crossed pairs which may arise if standards are mixed. T568B is the more commonly used standard in data applications. The standard requires that two outlets should be provided at each wall plate - one for voice, and one for data.
• Telecommunications  room/closet (or wiring) - an enclosed area, such as a room or a cabinet, for housing telecommunications equipment, distribution frames, cable terminations and cross connects. In other words, all the hardware required to connect horizontal wiring to vertical wiring. This area will often also house auxiliary equipment, including network file servers. Every building must have at least one wiring closet, and the standard recommends one per floor. Specific closet sizes are also recommended, depending on the size of the service area. There must be sufficient space for service personnel to perform maintenance and carry out other duties, as well as for all of the required hardware. Lighting, power supplies and environmental conditions should also meet the requirements specified by the standard.
• Equipment room - the space that houses building telecommunications systems such as PBXs, servers, switches etc., and the mechanical terminations of the telecommunications wiring system. It is considered to be different from a telecommunications closet because of the complexity of the components it houses. An equipment room can either take the place of a telecommunications closet or be a separate facility. The functions of an equipment room may even be incorporated in a wiring closet. The equipment room provides a termination point for vertical (backbone) cabling that is connected to one or more telecommunication closets. It may also be the main cross-connection point for the entire facility. In a campus environment, each building may have its own equipment room, to which telecommunication closet equipment is connected, and the equipment in this room may then be connected to a central campus facility that provides the main cross-connect for the entire campus.
• Entrance facility - contains the telecommunication service entrance to the building, and may also contain campus-wide backbone connections. It also contains the network demarcation point, which is the interconnection to the local exchange carrier's telecommunication facilities. The demarcation point is typically 12 inches from where the carrier's facilities enter the building, but the carrier may designate otherwise.
• Cabling administration - this is a process that includes all aspects of premise wiring activities related to documenting, managing, and testing the system, as well as compiling and maintaining the architectural plans for the system.

 

Structured cabling elements

The diagrams below show the relationship between the horizontal cabling elements in a structured cabling system for both a cross-connect and aninterconnect arrangement. In both cases, the permanent link is the telecommunications outlet (TO), the horizontal cabling, and the horizontal interconnect (patch panel). An optional transition point (TP) is allowed within the 90 metres of horizontal cabling.

 

 

Horizontal cabling elements

The channel is the work area cable (the patch lead) from the terminal equipment into the terminal outlet, the permanent link as already described, a patch cord linking two patch panels, and a final equipment cable into the LAN equipment. The use of two patch panels (a cross-connect) is optional. In many systems, only one is used (an interconnect). Note that in the interconnect version, the maximum combined length of patch cords A and B is 10 metres. In the cross-connect arrangement, the maximum combined length of patch cords A, B and C is also 10 metres.

Some requirements and recommendations

• Permanent links must not exceed 90 metres.
• The combined length of patch cords in any channel must not exceed 10 metres.
• There should be no more than two levels of cross-connect in the backbone. This allows a horizontal cross-connect between the horizontal cabling and the building backbone, and an intermediate cross-connect between the building backbone and a campus backbone, with all campus cables terminating in the main cross-connect.
• A total of 2000 metres of backbone cabling may be employed, consisting of up to 500 metres of building backbone and 1500 metres of campus backbone.
• Campus cabling links communications facilities in different buildings and is likely to be optical fibre.
• A minimum of one horizontal cross connect (or floor distributor) should be provided for every floor (one per 1000 m² of office space is recommended). One telecommunications outlet should be provided at each work area. A minimum of two per 10 m² of floor space is recommended.

Backbone cabling (including campus cabling) and horizontal cabling

Recommended Cabling
Horizontal	Vertical
100Ω 4-pair UTP cabling is recommended, as it has a relatively low cost and supports a range of applications. Enhanced Category 5 (Cat5E) is the suggested minimum specification, as it will support data rates of up to 1 Gbps. Many new installations are now employing Category 6 cabling to support current and future high-bandwidth applications. 150Ω 2-pair STP is generally used for Token Ring applications, although due to its extended bandwidth it can also be used for broadband video applications up to 300 MHz, or for 155-Mbps ATM. Coaxial cable is not recommended for horizontal wiring.	Fibre optic cable, although both more expensive more difficult to install than other types of cable, is the recommended transmission medium for backbone cabling, because it offers high speed transmission, high bandwidth, and carries data over much greater distances than copper cable. It is also immune to electromagnetic interference, and less likely to require replacement (fibre can also be used for horizontal wiring runs exceeding 100 metres). 100Ω 4-pair UTP cabling can also be used in short-to-medium distance vertical cabling in voice and data networks. 150Ω 2-pair STP can be used for Token Ring networks. 50Ω 10Base2 coaxial cable is recognised by the TIA/EIA standard as a suitable choice for economical vertical wiring, but it is rarely, if ever, used in new installations.

Based On

• http://www.technologyuk.net/telecommunications/networks/structured_cabling.shtml
• CCNA Discovery 4.0

Cisco - Port Mirror (SPAN / RSPAN / ERSPAN)

Introduction:

Switch port Analyzer (SPAN) is an efficient, high performance traffic monitoring system. It duplicated network traffic to one or more monitor interfaces as it transverse the switch. SPAN is used for troubleshooting connectivity issues and calculating network utilization and performance, among many others. There are three types of SPANs supported on Cisco products, which are illustrated in below diagram.

Types of SPAN:

SPAN

Local SPAN: Mirrors traffic from one or more interface on the switch to one or more interfaces on the same switch.
Remote SPAN (RSPAN): An extension of SPAN called remote SPAN or RSPAN. RSPAN allows you to monitor traffic from source ports distributed over multiple switches, which means that you can centralize your network capture devices. RSPAN works by mirroring the traffic from the source ports of an RSPAN session onto a VLAN that is dedicated for the RSPAN session. This VLAN is then trunked to other switches, allowing the RSPAN session traffic to be transported across multiple switches. On the switch that contains the destination port for the session, traffic from the RSPAN session VLAN is simply mirrored out the destination port.
Encapsulated remote SPAN (ERSPAN): encapsulated Remote SPAN (ERSPAN), as the name says, brings generic routing encapsulation (GRE) for all captured traffic and allows it to be extended across Layer 3 domains.

ERSPAN is a Cisco proprietary feature and is available only to Catalyst 6500, 7600, Nexus, and ASR 1000 platforms to date. The ASR 1000 supports ERSPAN source (monitoring) only on Fast Ethernet, Gigabit Ethernet, and port-channel interfaces.

Configuration Example:
Configuring Local SPAN: Local SPAN configures using “monitor session” command specifying source and destination on the same switch.

Switch1# configure terminal
Switch1(config)# monitor session 1 source interface fastEthernet0/2
Switch1(config)# monitor session 1 destination interface fastEthernet0/24
Switch1(config)#end

Local SPAN configuration syntax on Cisco IOS release 12.2(33)SXH and beyond as shown below.

monitor session 1 type local
source int fa0/2
destination int fa0/24

RSPAN

Step1: In order to configure RSPAN you need to have an RSPAN VLAN, those VLANs have special properties and can’t be assigned to any access ports. To create a VLAN for RSPAN on Cisco IOS, you must create the VLAN via the config-vlan configuration mode, as opposed to using the older VLAN database configuration mode. During the process of defining VLAN parameters, you must specify that the new VLAN is an RSPAN VLAN by configuring the remote-span VLAN configuration command.

Switch1# configure terminal
Switch1(config)# vlan 200
Switch1(config-vlan)# remote-span
Switch1(config-vlan)# end
Switch1# show vlan remote-span

Switch2# configure terminal
Switch2(config)# vlan 200
Switch2(config-vlan)# remote-span
Switch2(config-vlan)# end
Switch2# show vlan remote-span
Remote SPAN VLANs

Step2: Then configure the RSPAN on Source switch: Unlike SPAN, where the source and destination ports exist on the same switch, the source and destination ports for an RSPAN session reside on different switches. This requires a separate RSPAN source session to be configured, as well as a separate RSPAN destination session to be configured.

Switch1# configure terminal
Switch1(config)# monitor session 1 source interface fastEthernet0/2 rx
Switch1(config)# monitor session 1 destination remote vlan 200
reflector-port fastEthernet0/24
Switch1(config)# exit

Switch1# show monitor
Session 1
---------
Type                 : Remote Source Session
Source Ports     :
   Rx                 : Fa0/2
Reflector Port    : Fa0/24
Dest RSPAN VLAN  : 200

Step3: Configure the RSPAN on destination switch:
Switch2# configure terminal
Switch2(config)# monitor session 1 source remote vlan 200
Switch2(config)# monitor session 1 destination interface fastEthernet0/3
Switch2(config)# exit

The RSPAN VLAN should be allowed in ALL trunks between the involved switches (Source and Destination switches in this case); if you have enabled "pruning" in your network, remove the RSPAN VLAN from the pruning, with the command: “switchport trunk pruning vlan remove <RSPAN VLAN ID>” under the interface configure as trunk.

ERSPAN

In this example we will capture received traffic on the ASR 1002 (GigabitEthernet0/1/0) and send to Catalyst 6509 Gig2/2/1. This traffic will simply be captured, encapsulated in GRE by ASR 1002 natively by the QFP chipset and routed over to the Catalyst 6509. A sniffing station on the 6500 attached to GE2/2/1 will see the complete Ethernet frame (L2 to L7) information.
Configuring source interface, direction of traffic, and ERSPAN session ID on the ASR 1002.

ASR1002(config)# monitor session 1 type erspan-source
ASR1002(config-mon-erspan-src)# source interface gig0/1/0 rx
ASR1002(config-mon-erspan-src)# no shutdown
ASR1002(config-mon-erspan-src)# destination
ASR1002(config-mon-erspan-src-dst)# erspan-id 101
ASR1002(config-mon-erspan-src-dst)# ip address 10.1.1.1
ASR1002(config-mon-erspan-src-dst)# origin ip address 172.16.1.1

Configuring Catalyst 6509 to receive traffic from the source session on the ASR 1002

SW6509(config)# monitor session 2 type erspan-destination
SW6509(config-mon-erspan-dst)# destination interface gigabitEthernet2/2/1
SW6509(config-mon-erspan-dst)# no shutdown
SW6509(config-mon-erspan-dst)# source
SW6509(config-mon-erspan-dst-src)# erspan-id 101
SW6509(config-mon-erspan-dst-src)# ip address 10.1.1.1

You can use the show monitor session command to verify the configuration:

ASR1002#sh monitor session 1
Session 1
---------
Type                             : ERSPAN Source Session
Status                           : Admin Enabled
Source Ports                  :
RX Only                         : Gi0/1/0
Destination IP Address   : 10.1.1.1
MTU                              : 1464
Destination ERSPAN ID  : 101
Origin IP Address           : 172.16.1.1

To monitor the statistics of monitored traffic, you need to use "show platform hardware qfp active feature erspan state" command:

ASR1002#show platform hardware qfp active feature erspan state
ERSPAN State:
Status                : Active
Complexes         : 1
CPPs                 : 1
Capabilites          :
Max sessions      : 1024
Max outputs        : 128
Encaps type        : ERSPAN type-II
GRE protocol       : 0x88BE
MTU                    : 1464
IP TOS                : 0
IP TTL                 : 255
COS                   : 0
System Statistics:
DROP src session replica :                  0 /                 0
DROP term session replica:                 0 /                 0
DROP receive malformed   :                 0 /                 0
DROP receive invalid ID  :                    0 /                 0
DROP recycle queue full  :                   0 /                 0
DROP no GPM memory       :               0 /                 0
DROP no channel memory   :               0 /                 0
Client Debug Config:
Enabled: Info, Warn
Data Path Debug Config:
0x00000000
ASR1002#

Note:  10.1.1.1 is SW6509’s loopback. 172.16.1.1 Is ASR1002's loopback. ip address in destination session and ip address in source session should match. If they don't- that is causing the drops you see.

Taken From:

• https://supportforums.cisco.com/document/139236/understanding-spanrspanand-erspan

Linux - Schedule Tasks Using Crontab

Schedule Tasks on Linux Using Crontab

If you've got a website that's heavy on your web server, you might want to run some processes like generating thumbnails or enriching data in the background. This way it can not interfere with the user interface. Linux has a great program for this called cron. It allows tasks to be automatically run in the background at regular intervals. You could also use it to automatically create backups, synchronize files, schedule updates, and much more. Welcome to the wonderful world of crontab.

 

Crontab

The crontab (cron derives from chronos, Greek for time; tab stands fortable) command, found in Unix and Unix-like operating systems, is used to schedule commands to be executed periodically. To see what crontabs are currently running on your system, you can open a terminal and run:

$ sudo crontab -l

To edit the list of cronjobs you can run:

$ sudo crontab -e

This wil open a the default editor (could be vi or pico, if you want you canchange the default editor) to let us manipulate the crontab. If you save and exit the editor, all your cronjobs are saved into crontab. Cronjobs are written in the following format:

* * * * * /bin/execute/this/script.sh

 

Scheduling explained

As you can see there are 5 stars. The stars represent different date parts in the following order:

• minute (from 0 to 59)
• hour (from 0 to 23)
• day of month (from 1 to 31)
• month (from 1 to 12)
• day of week (from 0 to 6) (0=Sunday)

 

Execute every minute

If you leave the star, or asterisk, it means every. Maybe that's a bit unclear. Let's use the the previous example again:

* * * * * /bin/execute/this/script.sh

They are all still asterisks! So this means execute /bin/execute/this/script.sh:

• every minute
• of every hour
• of every day of the month
• of every month
• and every day in the week.

In short: This script is being executed every minute. Without exception.

 

Execute every Friday 1AM

So if we want to schedule the script to run at 1AM every Friday, we would need the following cronjob:

0 1 * * 5 /bin/execute/this/script.sh

Get it? The script is now being executed when the system clock hits:

• minute: 0
• of hour: 1
• of day of month: * (every day of month)
• of month: * (every month)
• and weekday: 5 (=Friday)

 

Execute on workdays 1AM

So if we want to schedule the script to Monday till Friday at 1 AM, we would need the following cronjob:

0 1 * * 1-5 /bin/execute/this/script.sh

Get it? The script is now being executed when the system clock hits:

• minute: 0
• of hour: 1
• of day of month: * (every day of month)
• of month: * (every month)
• and weekday: 1-5 (=Monday til Friday)

 

Execute 10 past after every hour on the 1st of every month

Here's another one, just for practicing

10 * 1 * * /bin/execute/this/script.sh

Fair enough, it takes some getting used to, but it offers great flexibility.

 

Neat scheduling tricks

What if you'd want to run something every 10 minutes? Well you could do this:

0,10,20,30,40,50 * * * * /bin/execute/this/script.sh

But crontab allows you to do this as well:

*/10 * * * * /bin/execute/this/script.sh

Which will do exactly the same. Can you do the the math? ; )

 

Special words

For the first (minute) field, you can also put in a keyword instead of a number:

• @reboot Run once, at startup
• @yearly Run once a year "0 0 1 1 *"
• @annually (same as @yearly)
• @monthly Run once a month "0 0 1 * *"
• @weekly Run once a week "0 0 * * 0"
• @daily Run once a day "0 0 * * *"
• @midnight (same as @daily)
• @hourly Run once an hour "0 * * * *"

Leaving the rest of the fields empty, this would be valid:

@daily /bin/execute/this/script.sh

 

Storing the crontab output

By default cron saves the output of /bin/execute/this/script.sh in the user's mailbox (root in this case). But it's prettier if the output is saved in a separate logfile. Here's how:

*/10 * * * * /bin/execute/this/script.sh >> /var/log/script_output.log 2>&1

 

Explained

Linux can report on different levels. There's standard output (STDOUT) and standard errors (STDERR). STDOUT is marked 1, STDERR is marked 2. So the following statement tells Linux to store STDERR in STDOUT as well, creating one datastream for messages & errors:

2>&1

Now that we have 1 output stream, we can pour it into a file. Where >will overwrite the file, >> will append to the file. In this case we'd like to to append:

>> /var/log/script_output.log

 

Mailing the crontab output

By default cron saves the output in the user's mailbox (root in this case) on the local system. But you can also configure crontab to forward all output to a real email address by starting your crontab with the following line:

MAILTO="yourname@yourdomain.com"

 

Mailing the crontab output of just one cronjob

If you'd rather receive only one cronjob's output in your mail, make sure this package is installed:

$ aptitude install mailx

And change the cronjob like this:

*/10 * * * * /bin/execute/this/script.sh 2>&1 | mail -s "Cronjob ouput" yourname@yourdomain.com

 

Trashing the crontab output

Now that's easy:

*/10 * * * * /bin/execute/this/script.sh > /dev/null 2>&1

Just pipe all the output to the null device, also known as the black hole. On Unix-like operating systems, /dev/null is a special file that discards all data written to it.

 

Caveats

Many scripts are tested in a BASH environment with the PATH variable set. This way it's possible your scripts work in your shell, but when run from cron (where the PATH variable is different), the script cannot find referenced executables, and fails.

It's not the job of the script to set PATH, it's the responsibility of the caller, so it can help to echo $PATH, and put PATH=<the result> at the top of your cron files (right below MAILTO).

Taken From: http://kvz.io/blog/2007/07/29/schedule-tasks-on-linux-using-crontab/

Cisco - Dual WAN Internet with Failover (NAT & Routes)

In the past I had the need to implement failover between two connections to the Internet on the same router, at the time I implemented it using EEM Scripts which wasn’t the most elegant solution, so here I’m going to show you a  a better solution to do this.

Implementing the failover mechanism at first glance seems easier with one router than with two, but that is not the case, with two routers you can have them configured normally with the adition of VRRP/HSRP to do the failover between the routers.

With only one router you are going to have two aditional problems:

• Changing the route from the primary to the secondary Internet access
• Changing the NAT overload to the Interface towards the Secondary ISP / WAN (this was the part that I implemented with EEM scripts)

the first you can easily solve with a floating static route (secondary route) and a track / ip sla (to remove the primary route when the connectivity to the primary ISP is lost).

The second one is harder, you can have two NAT rules with two interfaces towards the two ISPs:

ip nat inside source 130 interface FastEthernet0/0 overload
ip nat inside source 131 interface FastEthernet1/0 overload

but selecting the one as the active one is the tricky part.

Even if the interface towards the primary ISP were to fail and become shutdown, the NAT rule remains active.

The cenario bellow has two different ISPs for for the WAN accesses, but its the sames as having two different connectivities via the same ISP (eg. Primary via Fiber Optic | Secondary via 4G)

Cenario

Logical View

Fisical View

You can download the lab fully implemented here:

• 2015.10.18_Dual WAN Internet with Failover (RT & NAT) (DONE)_v2.zip

it was implemented on GNS3 v1.2.1.

 

Configuration

 

PC1
====================================================
enable
conf t

hostname PC1

interface FastEthernet0/0
description *** Link to CPE1 ***
ip address 192.168.1.1 255.255.255.0
no shutdown

ip route 0.0.0.0 0.0.0.0 192.168.1.254 name DefaultGW
 
do write
 
 
CPE1
====================================================
enable
conf t

hostname CPE1

interface FastEthernet0/0
description *** Link to ISP1 ***
ip address 11.0.0.2 255.255.255.252
ip nat outside
no shutdown
 
interface FastEthernet0/1
description *** Link to ISP2 ***
ip address 22.0.0.2 255.255.255.252
ip nat outside
no shutdown
 
interface FastEthernet1/0
no switchport
description *** Link to PC1 ***
ip address 192.168.1.254 255.255.255.0
ip nat inside
no shutdown

 
!-- Select the Route - via ISP1 or ISP2 -------------------
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
! The first route makes all the traffic flow via
! ISP1, but this is conditioned to track 10, that
! detects the  connectivity to ISP1.
! If track 10 fails the route is removed from the
! routing table.
!
!
! The second route has an higher administrative
! distance (worst), and as long as the first rule
! is available this rule is never inserted on
! the routing table (aka floating static route)
!
! If the first route disapears because the track
! failed then the second route is inserted in the
! routing table, and all traffic will flow via ISP2
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

ip route 0.0.0.0 0.0.0.0 11.0.0.1 track 10 name Default-Primary
ip route 0.0.0.0 0.0.0.0 22.0.0.1 250 name Default-Secondary

ip sla 10
icmp-echo 11.0.0.1 source-interface FastEthernet0/0
frequency 5
ip sla schedule 10 life forever start-time now

track 10 ip sla 10 reachability
!show track brief
!show track 10

!-- Change the NAT Interface to Reflect the Active Route --
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
! Changing the routes isn't enough, we also
! need to change the NAT rule, because each route
! implies a different exit interface.
!
! To select which NAT rule will be used for each
! route, we used route maps instead of an ACL
! to identify traffic (active the rule).
!
! These route maps match the LAN traffic, plus
! the current next hop to forward the traffic thus
! selecting the correct NAT rule for the current
! active route.
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

ip nat inside source route-map RM-ISP1-PRIMARY interface FastEthernet0/0 overload
ip nat inside source route-map RM-ISP2-PRIMARY interface FastEthernet0/1 overload

access-list 130 remark *** Traffic for The Internet (NAT) ***
access-list 130 permit ip 192.168.1.0 0.0.0.255 any

route-map RM-ISP1-PRIMARY permit 10
match ip address 130
match interface FastEthernet0/0        !--> Match the exit interface of the route

route-map RM-ISP2-PRIMARY permit 10
match ip address 130
match interface FastEthernet0/1        !--> Match the exit interface of the route
!show route-map

!-- Simulate a Failure Along The Way ----------------------
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
! To simulate the failure to see the topology
! changing to the secondary access, we are going
! to use a route to force the track/ip sla to fail.
!
! This route will force all the connectivity test
! traffic destined for ISP1(11.0.0.1) to go to NULL
! which is a black hole. Like this ISP1 will never
! get the icmp echos requests from the ip sla test
! or respond to it, thus simulating a connectivity
! failure towards ISP1
!
! NOTE: It takes a couple of seconds to change
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

!-- Failure Sim + Debug/Tshoot --
do debug ip nat
ping 77.0.0.1
show ip route
!S*    0.0.0.0/0 [1/0] via 11.0.0.1

ip route 11.0.0.1 255.255.255.255 NULL0 name FailureSim

ping 77.0.0.1
show ip route
!S*    0.0.0.0/0 [250/0] via 22.0.0.1

! Both Pings will work but notice that the default
! route is diferent (diferent next hop)

!-- Restore to Normal Operation --
no ip route 11.0.0.1 255.255.255.255 NULL0 name FailureSim
do no debug all

ISP1-PRIMARY
====================================================
enable
conf t

hostname ISP1-PRIMARY

interface FastEthernet0/0
description *** Link to CPE1 ***
ip address 11.0.0.1 255.255.255.252
no shutdown

interface FastEthernet0/1
description *** Link to CPE2 ***
ip address 11.0.0.5 255.255.255.252
no shutdown
 
 
interface FastEthernet1/0
no switchport
description *** Link to ISP2 ***
ip address 22.0.0.6 255.255.255.252
no shutdown

    
ip route 77.0.0.0 255.255.255.248 11.0.0.6 name PublicIPs
ip route 22.0.0.0 255.255.255.252 22.0.0.5 name NatedLAN-viaIPS2

do write

ISP2-SECONDARY
====================================================
enable
conf t

hostname ISP2-SECONDARY

interface FastEthernet0/1
description *** Link to CPE1 ***
ip address 22.0.0.1 255.255.255.252
no shutdown
 
interface FastEthernet0/0
description *** Link to ISP1 ***
ip address 22.0.0.5 255.255.255.252
no shutdown

ip route 0.0.0.0 0.0.0.0 22.0.0.6 name Default
 
do write
 
 
CPE2
====================================================
enable
conf t

hostname CPE2

interface FastEthernet0/1
description *** Link to ISP1 ***
ip address 11.0.0.6 255.255.255.248
no shutdown
 
interface FastEthernet1/0
description *** Link to Internet Server ***
no switchport
ip address 77.0.0.6 255.255.255.248

ip route 0.0.0.0 0.0.0.0 11.0.0.5 name Default

do write

INTERNET SERVER
====================================================
enable
conf t

hostname INTERNET-SERVER

interface FastEthernet0/0
description *** Link to CPE1 ***
ip address 77.0.0.1 255.255.255.248
no shutdown
 
ip route 0.0.0.0 0.0.0.0 77.0.0.6 name Default

do write

Related Links

• http://docwiki.cisco.com/wiki/NAT_failover_with_DUAL_ISP_on_a_router_Configuration_Example

Linux/Raspberry - Send Emails (SMTP Setup - Gmail)

 

SMTP Mail Setup

Many times you want to have the ability to send email from processes on your Raspberry Pi to email addresses out on the network. Adding email to your Raspberry Pi is pretty simple. You can use the following three packages for some simple mail capabilities.

It is assumed that you have networking working already...

 

Loading the packages

sudo apt-get install ssmtp
sudo apt-get install mailutils
sudo apt-get install mpack

Setting up the defaults for SSMTP

sudo nano /etc/ssmtp/ssmtp.conf

Now edit the fields:

AuthUser=youruserid@gmail.com
AuthPass=userpass
FromLineOverride=YES
mailhub=smtp.gmail.com:587
UseSTARTTLS=YES

Using Email Now

echo "sample text" | mail -s "Subject" username@domain.tld

Sending Attachments

mpack -s "test" /home/pi/test/somefile.ext username@domain.tld

Taken From:

• https://rpi.tnet.com/project/faqs/smtp

How to Mount CD/DVDs Images - Windows, Mac, and Linux

Disc images have become more useful than ever on modern PCs that often lack CD and DVD drives. Create ISO files and other types of disc images and you can “mount” them, accessing the virtual discs as if they were physical discs inserted into your computer.

You can also use these image files to burn copies of the original discs later, creating duplicate copies. Disc image files contain a complete representation of a disc.

 

Windows

Windows 10 allows you to mount both .ISO and .IMG disc image files without any third-party software. Just double-click a .ISO or .IMG disc image you want to make available. If this doesn’t work, you should be able to click the “Disk Image Tools” tab on the ribbon and click “Mount.” It will appear under Computer as if it were inserted into a physical disc drive.

This feature was added back in Windows 8, so it will also work on Windows 8 and 8.1.

To unmount the disc later, right-click the virtual disc drive and select “Eject.” The disc will be unmounted and the virtual disc drive will disappear from the Computer window until you mount a disc in it again.

To mount ISO or IMG images on Windows 7 — or to mount images in other formats, such as BIN/CUE, NRG, MDS/MDF, or CCD — we recommend the free, open-source, and simple WinCDEmu utility.

Just right-click an image file after installing it, click “Select drive letter & mount,” and you can mount other types of images Windows doesn’t support.

Some other third-party utilities have additional support for emulating various copy-protection technologies, allowing copy-protected discs to function normally. However, such techniques are being phased out and aren’t even supported by modern versions of Windows.

 

Mac

On a Mac, double-clicking common disc image formats will mount them. This is why you can simply double-click a downloaded .DMG file to access its contents and install Mac applications, for example.

The DiskImageMounter application that handles this can also mount .ISO, .IMG, .CDR, and other types of image files. Just double-click the file to mount it. If this doesn’t work, Option-click or right-click a file, point to “Open With,” and select “DiskImageMounter.”

When you’re done, just click the “Eject” button next to the mounted image in the Finder’s sidebar to eject it and unmount it — just like you’d unmount a .DMG image when you’re done with it.

You can also try mounting the disc image file by opening the Disk Utility application. Press Command+Space, type Disk Utility, and press Enter to open it. Click the “File” menu, select “Open Image,” and select the disc image you want to mount.

 

Linux

Ubuntu’s Unity desktop and GNOME include an “Archive Mounter” application that can mount ISO files and similar image files graphically. To use it, right-click an .ISO file or another type of disc image, point to Open With, and select “Disk Image Mounter.”

You can later unmount the image by clicking the eject icon next to the mounted image in the sidebar.

You can also mount an .ISO file or another disc image with a Linux terminal command. This is particularly useful if you’re just using the command line, or if you’re using a Linux desktop that doesn’t provide a tool to make this easy. (Of course, graphical tools for mounting ISO files and similar images may be available in your Linux distribution’s software repositories.)

To mount an ISO or IMG file on Linux, first open a Terminal window from your Linux desktop’s applications menu. First, type the following command to create the /mnt/image folder. You can create practically any folder you like — you just have to create a directory where you’ll mount the image. The contents of the disc image will be accessible at this location later.

sudo mkdir /mnt/image

Next, mount the image with the following command. Replace “/home/NAME/Downloads/image.iso” with the path to the ISO, IMG, or other type of disc image you want to mount.

sudo mount -o loop /home/NAME/Downloads/image.iso /mnt/image

To unmount the disc image later, just use the umount command:

sudo umount /mnt/image

Some guides recommend you add “-t iso9660” to the command. However, this isn’t actually helpful - it’s best to let the mount command automatically detect the required file system.

If you’re trying to mount a more obscure type of disc image format that the mount command can’t automatically detect and mount in this way, you may need commands or tools designed specifically for working with that type of image file format.

This should “just work” on most modern operating systems, allowing you to mount and use ISO images and other common types of image files in a few clicks. Windows 7 users will have the toughest time, as it isn’t integrated into that older version of Windows, but WinCDEmu is a lightweight and easy way to accomplish this.

Taken From:

• http://www.howtogeek.com/230468/how-to-mount-isos-and-other-disc-images-on-windows-mac-and-linux/