MBSA AUTHORIZED REMOTE SCAN

How to run Microsoft Baseline Security Analyzer remotely with a user credentials?

1. Run command prompt as an administrator.

2. Switch the path to the MBSA parth.
cd c:\Program Files\Microsoft Baseline Security Analyzer 2\

3. Run MBSA as a specific user on a remote machine.
c:\Program Files\Microsoft Baseline Security Analyzer 2>runas /netonly /user:10.10.10.240\user mbsa.exe

4. Enter the password for 10.10.10.240\user:

Attempting to start mbsa.exe as user "10.10.10.240\user" ...
c:\Program Files\Microsoft Baseline Security Analyzer 2>

It will start MBSA with given user name "user" and password.

5. As MBSA shown up then press "Scan a computer"

6. Add IP address of destination computer and press "Start Scan"

HOW ETHERCHANNEL WORKS?

The Inner Workings of EtherChannel

EtherChannel is a very important technology for modern networks. As bandwidth demands continue to increase with more and more traffic forms converging onto the single network infrastructure, EtherChannels importance is magnified even more. 

Link Aggregation Protocols

As mentioned earlier, EtherChannel actually aggregates individual Ethernet links into a single logical link that provides bandwidth up to 1600 Mbps, in the case of Fast Ethernet, or 16 Gbps when Gigabit interfaces are used to create the logical link. The restriction, however, is that all the bundled interfaces must be configured with matching speed and duplex settings, and both ends of each link must be configured as either a Layer 2 or Layer 3 interface. 

If an individual link within an EtherChannel bundle fails, traffic previously carried over the failed link is carried over the remaining links within the EtherChannel.

An EtherChannel can be configured in one of these two dynamic modes:

• Port Aggregation Protocol (PAgP) is a Cisco proprietary protocol used to automate the logical aggregation of Ethernet switch ports. This means PAgP can only be used between Cisco switches. 

• Link Aggregation Control Protocol (LACP) is an industry standard protocol designed to automate the logical aggregation ethernet ports. Also know by its IEEE designation 802.3ad LACP is not tied to any specific vendor.

Port Aggregation Protocol (PAgP)

As we have already discussed, PAgP packets are sent between EtherChannel capable ports to facilitate the negotiation needed for the successful creation of a channel. When PAgP sees matched Ethernet links, it will group the links into an EtherChannel. 

PAgP uses three modes of operation:

• Auto—places an interface into a passive negotiating state, meaning that the interface will respond to PAgP packets it receives but it will not initiate PAgP packet negotiation. This setting minimizes the transmission of PAgP packets and is the default on devices like Catalyst 3560.

• Desirable—places an interface into an active negotiating state, meaning that the interface will start negotiations with other interfaces by sending PAgP packets.

• On—forces the interface to channel without PAgP. With the on mode, a usable EtherChannel exists only when an interface group in the on mode is connected to another interface group in the on mode. This is referred to as static aggregation.

Link Aggregation Control Protocol (LACP)

LACP performs the exact same function as the Cisco proprietary PAgP but it does it by sending LACP packets to its peer. Because LACP is an IEEE standard, it can be used to facilitate EtherChannels in mixed vendor environments.

LACP, like PAgP, has three modes of operation:

• Passive— The switch does not initiate the channel, but does respond to incoming LACP packets. When a peer initiates negotiation (by sending out an LACP packet) which we receive and reply to, eventually forming the aggregation channel with the peer. This is similar to the auto mode in PAgP.

• Active—We are willing to form an aggregate link and will actively seek to start the negotiation. The link aggregate will be formed if the other end is running in LACP active or passive mode. This is similar to the desirable mode of PAgP.

• On—A link aggregation is forced to be formed without any LACP negotiation. In other words, the switch will neither send the LACP packet nor process any incoming LACP packet. This is similar to the on state for PAgP. Again, this is referred to as static aggregation.

Configuration 

We only need a single command line to configure a group of ports to operate as an EtherChannel:

SW1(config)# interface range f0/23 -24

SW1(config-if-range)# channel-group 23 mode active

Creating a port-channel interface Port-channel 23

As expected, we have successfully created the logical interface Port-channel23. Note that any switchport configurations applied to this virtual interface will be replicated to the physical member interfaces. We can verify the configuration and the status of an EtherChannel by using the 'show EtherChannel summary' command:

SW1# show EtherChannel summary

Flags: D–down P–bundled in port-channel

I–stand-alone s–suspended

H–Hot-standby (LACP only)

R–Layer3 S–Layer2

U–in use f–failed to allocate aggregator

------+-------------+-----------+-------------------------------

1 Po23(SD) LACP Fa0/23(D) Fa0/24(D)

HOW STP WORKS

How Spanning Tree Protocol Works?

When a switch first power up it assumes that it is the Root Bridge itself and switch begins by sending out BPDUs with a Root Bridge ID and Sender ID equal to its own Bridge ID. As the BPDU goes out through the network, each switch compares its own BPDU with the one that switch receives from the neighbors. The comparison is done on bridge ID. When a switch hears of a better Root Bridge (lower bridge ID), it replaces its own Root Bridge ID with the Root Bridge ID announced in the BPDU although it still identifies itself as the Sender Bridge ID. After sometime the switch with the lowest bridge ID in the network wins this Root Bridge election process. 

• STP Rule 1: All ports of the root bridge will be in forwarding mode. 

o Next, each switch determines the best path to get to the root. The switches determine this path based on Root Path Cost. This value is the cumulative cost of all the links leading to the Root Bridge. The switch uses the port with the least Root Path Cost in the BPDU in order to get to the root switch; the port with the least Root Path Cost in the BPDU is the root port. 

• STP Rule 2: The root port must be set to forwarding mode. 

o In addition, the switches on each LAN segment communicate with each other to determine which switch is best to use in order to move data from that segment to the root bridge and this determination is based on the lowest cumulative Root Path Cost to the Root Bridge. And the port is called the designated port. 

• STP Rule 3: The designated port must be set to forwarding mode. 

• STP Rule 4: All the other ports in all the switches must be placed in blocking mode. 

If two or more links might identical Root Path Costs then that will results in a tie condition. All tiebreaking STP decisions are based on the following sequence of four conditions:

• Lowest Root Bridge ID

• Lowest Root Path Cost to Root Bridge

• Lowest Sender Bridge ID

• Lowest Sender Port ID

STP PORT STATE:

• Blocking:

All the port by default on a switch will be in the blocking state. In blocking state we are only allowed to receive BPDU. We can't build our MAC Table at this state.

• Listening:

If the port on the switch is administratively enabled it move to listening state. At this state it can receive and transmit BPDU. Hence it involved in the election of Root Bridge. This state has a timer enabled which has to be elapsed before getting to the next state. This timer is called as forward delay timer and its default value is 15sec. 

• Learning:

At this state port can receive and transmit BPDU and also can start building MAC table. But it can't receive or transmit data frames at this state. This state also has forward delay timer and the default value of the timer is 15sec.

• Forwarding:

At this state port can receive and transmit BPDU & DATA Frames and also we will continue to build our MAC table.