Chapter Objectives After successfully completing this chapter, you will be
able to: •
Describe the storm control security feature
•
Configure and monitor the storm control security feature
•
Describe firewall filter support for EX Series switches
•
Implement Implement and monitor the t he effects of a firewall filter
Agenda: Device Security and Firewall Filters Storm Control Firewall Filters
Traffic Storms Some traffic types, such as broadcast and unknown
unicast, can continuously propagate through a LAN consuming resources and affecting performance User A initiates traffic to a destination MAC address not known or located in the network
User A MAC: 00:26:88:02:74:86
Switch-1
Switch-2
User B MAC: 00:26:88:02:74:87
User C MAC: 00:26:88:02:74:88
User D MAC: 00:26:88:02:74:89
Switch-3
User E MAC: 00:26:88:02:74:90
User F MAC: 00:26:88:02:74:91
Introducing Storm Control Storm control monitors traffic levels and drops traffic
when the threshold (storm control level) is exceeded •
Prevents traffic from proliferating and degrading the LAN Switch-1
Storm Control Configuration Storm control is enabled by default on EX switches •
Default storm control level is 80 percent for all interfaces
You can modify the default configuration settings at the [edit ethernet-switching-options] hierarchy
Changing the Default Configuration Before modifying the default configuration, monitor
broadcast, multicast, and unknown unicast traffic levels in LAN under normal operating conditions •
•
Use benchmark data to determine acceptable traffic levels Configure storm control to set the level at which you want to drop broadcast traffic, multicast traffic, unknown unicast traffic, or all three.
Storm Control Actions When the storm control level is exceeded, the switch
can either drop offending traffic (default) or shut down the interface through which the traffic is passing {master:0}[edit ethernet-switching-options] user@Switch-1# show storm-control { interface all; }
{master:0}[edit ethernet-switching-options] user@Switch-1# show storm-control { action-shutdown; interface all; } Use the action-shutdown option to alter the default behavior
Automatic Error Condition Recovery By default, when the
action-shutdown option is used and the storm control level is exceeded the interface is shut down until it is manually re-enabled
Alternatively, you can automate error condition recovery using the port-error-disable option:
{master:0}[edit ethernet-switching-options] user@Switch-1# show port-error-disable { Specify a disable timeout value disable-timeout 300; between 10 and 3600 seconds } storm-control { action-shutdown; interface all; }
Monitoring Automatic Recovery You can monitor the automatic recovery process by: •
Using show ethernet-switching interfaces to view interface state details:
{master:0} user@Switch-1> show Interface State ge-0/0/6.0 up ge-0/0/8.0 up ge-0/0/9.0 down
ethernet-switching interfaces VLAN members Tag Tagging v11 11 untagged v11 11 tagged v11 11 tagged
me0.0
mgmt
•
up
Blocking unblocked unblocked Storm control in effect (00:03:57) remaining untagged unblocked
Using show log messages to view violation details:
{master:0} user@Switch-1> show log messages | match storm | match ge-0/0/9 Jul 29 09:38:23 Switch-1 eswd[856]: ESWD_ST_CTL_ERROR_DISABLED: ge-0/0/9.0: storm control disabled port Jul 29 09:43:23 Switch-1 eswd[856]: ESWD_ST_CTL_ERROR_ENABLED: ge-0/0/9.0: storm control enabled port Interface was re-enabled after disable timeout period (5 minutes)
Clearing Violations Manually Use
clear ethernet-switching port-error interface to clear violations manually:
{master:0} user@Switch-1> show Interface State ge-0/0/6.0 up ge-0/0/8.0 up ge-0/0/9.0 down
ethernet-switching interfaces VLAN members Tag Tagging v11 11 untagged v11 11 tagged v11 11 tagged
me0.0
mgmt
up
Blocking unblocked unblocked Storm control in effect (00:04:17) remaining untagged unblocked
{master:0} user@Switch-1> clear ethernet-switching port-error interface ge-0/0/9 {master:0} user@Switch-1> show Interface State ge-0/0/6.0 up ge-0/0/8.0 up ge-0/0/9.0 up me0.0 up
ethernet-switching interfaces VLAN members Tag Tagging v11 11 untagged v11 11 tagged v11 11 tagged mgmt untagged
Blocking unblocked unblocked unblocked unblocked
Agenda: Device Security and Firewall Filters Storm Control Firewall Filters
Firewall Filters: A Review Firewall filters control the traffic entering and leaving
Applied to Layer 2 switch ports in ingress and egress directions
VLAN-based
Applied to Layer 2 VLANs in the ingress and egress directions
Router-based
Applied to Layer 3 routed interfaces in ingress and egress directions
{master:0}[edit firewall] user@Switch-1# edit family ? Possible completions: > any Protocol-independent filter > ethernet-switching Protocol family Ethernet Switching for firewall filter > inet Protocol family IPv4 for firewall filter > inet6 Protocol family IPv6 for firewall filter
Port-based and VLAN-based filters use family ethernet-switching option while routerbased filters use family inet or family inet6 depending on the traffic type
Processing Order of Firewall Filters Processing order considerations: Ingress processing order is port, VLAN, then router Egress processing is performed in the reverse order A router-based filter applied to an RVI does not apply to switched packets in the same VLAN •
• •
Router Filter
Router Filter
VLAN Filter
VLAN Filter
Port Filter
Port Filter
Rx Packet
Tx Packet
Input
Output
Building Blocks of Firewall Filters Firewall filters consist of one or more terms; the software evaluates terms sequentially until it reaches a terminating action
my-filter User-defined filter and term names
term firstterm
from
then
match no match
term secondterm from statements describe match conditions
from
then
match no match
then statements describe the actions to take if a match with the from statement occurs
term Default
discard
Default action for packets not explicitly allowed
Note: Ordering matters! If you must reorder terms within a filter, consider using the insert CLI command.
Common Match Criteria Can match based on most header fields:
Match conditions categories include: Numeric range Address Bit field •
• •
term firstterm The from statements describe match conditions
from
then match
Firewall Filter Actions Common actions in firewall filters: •
•
Terminating actions: •
accept
•
discard
•
reject
Action modifiers: •
•
•
analyzer, count, log, and syslog forwarding-class and loss-priority policer term firstterm
from
then match
The then statements describe actions to take
Note: The software discards all traffic not explicitly allowed!
Case Study: Topology and Objectives Objectives: •
Implement filters on the access ports so that only frames using the expected source MAC addresses are permitted •
•
Discard and count frames sourced from any other MAC addresses
Implement a filter on both VLANs to block frames destined to MAC address 01:80:c2:00:00:00 •
Discard and count frames destined to the referenced MAC address User A - (VLAN: v11) 172.23.11.100/24 MAC: 00:26:88:02:74:86
Access ports User B - (VLAN: v12) 172.23.12.100/24 MAC: 00:26:88:02:74:87
Case Study: Configuring the Filters (1 of 2) {master:0}[edit firewall family ethernet-switching] user@Switch-1# show filter limit-MAC-ge006 term 1 { from { source-mac-address { 00:26:88:02:74:86; } } then accept; } term 2 { then { discard; count ge006-invalid-MAC; } }
{master:0}[edit firewall family ethernet-switching] user@Switch-1# show filter limit-MAC-ge007 term 1 { from { source-mac-address { 00:26:88:02:74:87; } } then accept; } term 2 { then { discard; count ge007-invalid-MAC; } }
User A - (VLAN: v11) 172.23.11.100/24 MAC: 00:26:88:02:74:86
Access ports User B - (VLAN: v12) 172.23.12.100/24 MAC: 00:26:88:02:74:87
Case Study: Configuring the Filters (2 of 2) {master:0}[edit firewall family ethernet-switching] user@Switch-1# show filter block-dest-MAC-01:80:c2:00:00:00 term 1 { from { destination-mac-address { 01:80:c2:00:00:00; } } then { discard; count block-stp-bpdus; } } term 2 { then accept; } User A - (VLAN: v11) 172.23.11.100/24 MAC: 00:26:88:02:74:86
Access ports User B - (VLAN: v12) 172.23.12.100/24 MAC: 00:26:88:02:74:87
Case Study: Applying the Filters (1 of 2) {master:0}[edit interfaces] user@Switch-1# show ge-0/0/6 unit 0 { family ethernet-switching { vlan { members v11; } filter { input limit-MAC-ge006; } } }
{master:0}[edit interfaces] user@Switch-1# show ge-0/0/7 unit 0 { family ethernet-switching { vlan { members v12; } filter { input limit-MAC-ge007; } } }
User A - (VLAN: v11) 172.23.11.100/24 MAC: 00:26:88:02:74:86
Access ports User B - (VLAN: v12) 172.23.12.100/24 MAC: 00:26:88:02:74:87
Case Study: Applying the Filters (2 of 2) {master:0}[edit vlans] user@Switch-1# show v11 { vlan-id 11; filter { input block-dest-MAC-01:80:c2:00:00:00; } l3-interface vlan.11; } v12 { vlan-id 12; filter { input block-dest-MAC-01:80:c2:00:00:00; } l3-interface vlan.12; } User A - (VLAN: v11) 172.23.11.100/24 MAC: 00:26:88:02:74:86
Access ports User B - (VLAN: v12) 172.23.12.100/24 MAC: 00:26:88:02:74:87
Case Study: Monitoring Firewall Filters {master:0} user@Switch-1> show firewall Filter: block-dest-MAC-01:80:c2:00:00:00 Counters: Name block-stp-bpdus
Bytes 472
Packets 7
Filter: limit-MAC-ge006 Counters: Name ge006-invalid-MAC
Bytes 1148
Packets 12
Filter: limit-MAC-ge007 Counters: Name ge007-invalid-MAC
Bytes 842
Packets 9
User A - (VLAN: v11) 172.23.11.100/24 MAC: 00:26:88:02:74:86
Access ports User B - (VLAN: v12) 172.23.12.100/24 MAC: 00:26:88:02:74:87
Summary In this chapter, we: •
Described the storm control security feature
•
Configured and monitored the storm control security feature
•
Described firewall filter support for EX Series switches
•
Implemented and monitored the effects of a firewall filter
Review Questions 1. What is a traffic storm and how is it created? 2. What actions can be taken when a storm control level is exceeded? 3. Which types of firewall filters are supported on EX Series switches? Where are they applied?
Lab 5: Storm Control and Firewall Filters Implement the storm control security feature. Configure and monitor firewall filters.
