This document describes the useful commands for troubleshooting ZBF related issues.
What is Zone Based Firewall?
Security zone: It is a group of interfaces to which a policy can be applied. By default, traffic can flow freely within that zone but all traffic to and from that zone is dropped by default. To allow traffic pass between zones, administrators must explicitly declare by creating a zone-pair and a policy for that zone. Another notice is that traffic originated from the router itself is allowed to pass freely.
Zone-pair : allows you to specify a uni-directional firewall policy between two zones. In other words, a zone-pair specifies the direction of the interesting traffic. This direction is defined by specifying a source and destination zone. Notice that we can’t defined a zone as both source and destination zone.
Zone Policy : defines what we want to allow or deny to go between zones. For example we just want to allow HTTP while dropping SMTP, ICMP… We have 3 actions “pass”, “drop” and “inspect”. The “pass” and “drop” actions are self-explanatory. The action “inspect” tell the router to use a pre-defined class-map to filter the traffic.
Prerequisites:
1.Router running IOS Firewall feature set image
2.ZBF Configuration
Procedure:
1.Logging Commands
ip inspect log drop-pkt <<<< Enabling router to log dropped packets the above command is replaced by the following global parameter map that configures logging settings across the entire device
parameter-map type inspect global
log dropped-packets enable
log summary flows 256 time-interval 30
Using class specific parameter map that configures logging settings to a specific class-map
parameter-map type inspect TCP_PARAM audit-trail on alert on class-map type inspect match-all TCP_CMAP match protocol tcp policy-map type inspect IN_TO_OUT_PMAP class type inspect TCP_CMAP inspect TCP_PARAM class class-default drop
2.Show Commands
show policy-map type inspect zone-pair zone-pair-name sessions <<<< To check current connections
show zone security zone-name <<<< Show which interfaces are assigned to a zone
show zone-pair security <<<< Shows the interfaces and service-policy for each zone-pair
3.Debug Commands
Basic debug: can be run without a strong threat of the router crashing
debug policy-firewall protocol tcp
debug policy-firewall detail
debug policy-firewall obj-cre
debug policy-firewall obj-del
debug policy-firewall events
debug policy-firewall list <ACL_num> <<<< use this command to filter the above debug output on the specific flow defined by ACL.
Advanced debug: much more verbose and run a higher threat of crashing the router
debug cce dp target detailed
debug cce dp target detailed internal
debug cce dp named-db detailed
debug cce dp named-db detailed internal
debug cce dp named-db inspect
debug cce dp named-db inspect detail
debug cce dp named-db inspect pak
debug cce dp feature inspect detail <<<< 15.1 and later version
I configured on my router a parameter map for Dos attack.
Inside Parameter map I configured this:
tcp max-incomplete host 2 block-time 15
I checked it and it works. My question are:
Can I see who is the blocked host?
How can I see that information?
Many thanks in advance
Regards,
Fabrizio
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