IP Access Control Lists (ACL), Prefix Lists, and Route-maps |
139
•
Second and subsequent fragments are allowed because a Layer 4 rule cannot be applied to these
fragments. If the packet is to be denied eventually, the first fragment would be denied and hence the
packet as a whole cannot be reassembled.
•
Implementing the required rules will use a significant number of CAM entries per TCP/UDP entry.
•
For IP ACL, FTOS always applies implicit deny. You do not have to configure it.
•
For IP ACL, FTOS applies implicit permit for second and subsequent fragment just prior to the
implicit deny.
•
If an
explicit
deny is configured, the second and subsequent fragments will not hit the implicit permit
rule for fragments.
•
Loopback interfaces do not support ACLs using the IP fragment option. If you configure an ACL with
the fragments option and apply it to a loopback interface, the command is accepted, but the ACL
entries are not actually installed the offending rule in CAM.
IP fragments ACL examples
The following configuration permits all packets (both fragmented & non-fragmented) with destination IP
10.1.1.1. The second rule does not get hit at all.
To deny second/subsequent fragments, use the same rules in a different order. These ACLs deny all second
& subsequent fragments with destination IP 10.1.1.1 but permit the first fragment & non fragmented
packets with destination IP 10.1.1.1 .
Layer 4 ACL rules examples
In the below scenario, first fragments non-fragmented TCP packets from 10.1.1.1 with TCP destination
port equal to 24 are permitted. All other fragments are denied.
FTOS(conf)#ip access-list extended ABC
FTOS(conf-ext-nacl)#permit ip any 10.1.1.1/32
FTOS(conf-ext-nacl)#
deny ip any 10.1.1.1./32 fragments
FTOS(conf-ext-nacl)
FTOS(conf)#ip access-list extended ABC
FTOS(conf-ext-nacl)#
deny ip any 10.1.1.1/32 fragments
FTOS(conf-ext-nacl)#permit ip any 10.1.1.1/32
FTOS(conf-ext-nacl)
FTOS(conf)#ip access-list extended ABC
FTOS(conf-ext-nacl)#
permit tcp host 10.1.1.1 any eq 24
FTOS(conf-ext-nacl)#deny ip any any fragment
FTOS(conf-ext-nacl)
Summary of Contents for Force10 E300
Page 1: ...FTOS Configuration Guide FTOS 8 4 2 7 E Series TeraScale C Series S Series S50 S25 ...
Page 32: ...32 w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 132: ...132 802 1X w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 310: ...310 Configuration Replace and Rollback w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 330: ...330 Dynamic Host Configuration Protocol w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 402: ...402 High Availability w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 462: ...462 Interfaces w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 482: ...482 IPv4 Addressing w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 506: ...506 IPv6 Addressing w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 582: ...582 Layer 2 w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 642: ...642 Multicast Source Discovery Protocol w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 662: ...662 Multiple Spanning Tree Protocol w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 690: ...690 Object Tracking w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 754: ...754 PIM Dense Mode w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 784: ...784 PIM Source Specific Mode w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 800: ...800 Power over Ethernet w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 876: ...876 Quality of Service w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 892: ...892 Routing Information Protocol w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 1006: ...1006 Simple Network Management Protocol w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 1018: ...1018 SONET SDH w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 1048: ...1048 Broadcast Storm Control w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 1096: ...1096 Uplink Failure Detection UFD w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 1098: ...1098 Upgrade Procedures w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 1196: ...1196 C Series Debugging and Diagnostics w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 1252: ...1252 Standards Compliance w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 1262: ...1262 Index w w w d e l l c o m s u p p o r t d e l l c o m ...