07-26-2010 06:53 AM - edited 03-11-2019 11:16 AM
Can Someone put some light on the Order of Operations (what all happnes when paket comes to interface) in ASA/PIX. Is there any difference when direction changes.
07-26-2010 07:40 AM
Perhaps this is what you were looking for?
07-26-2010 07:42 AM
Hi,
Actually the list is quite long and detailed... depending on the features that you have...
But just to give you an example...
When a packet comes to an interface normally this happens:
ACL checking
Routing
NAT
Encryption
Obviously, if you have other features like AAA, application inspection, etc... then they also come into play.
When the packet arrives to its destination, the packet is first decrypted, and then all the rule applies.
The above is very general and is just to give you an idea.
Federico.
07-26-2010 08:54 AM
The Packet-Tracer option will provide all this informacion
https://www.cisco.com/en/US/products/ps6120/products_tech_note09186a00807c35e7.shtml#s3
Phase: 1
Type: CAPTURE
Subtype:
Result: ALLOW
Config:
Additional Information:
MAC Access list
Phase: 2
Type: ACCESS-LIST
Subtype:
Result: ALLOW
Config:
Implicit Rule
Additional Information:
MAC Access list
Phase: 3
Type: FLOW-LOOKUP
Subtype:
Result: ALLOW
Config:
Additional Information:
Found no matching flow, creating a new flow
Phase: 4
Type: ROUTE-LOOKUP
Subtype: input
Result: ALLOW
Config:
Additional Information:
in 172.22.1.0 255.255.255.0 outside
Phase: 5
Type: ACCESS-LIST
Subtype: log
Result: ALLOW
Config:
access-group inside_acl in interface inside
access-list inside_acl extended permit tcp 192.168.1.0 255.255.255.0 any eq www
Additional Information:
Phase: 6
Type: IP-OPTIONS
Subtype:
Result: ALLOW
Config:
Additional Information:
Phase: 7
Type: CAPTURE
Subtype:
Result: ALLOW
Config:
Additional Information:
Phase: 8
Type: NAT
Subtype:
Result: ALLOW
Config:
nat (inside) 1 192.168.1.0 255.255.255.0
match ip inside 192.168.1.0 255.255.255.0 outside any
dynamic translation to pool 1 (172.22.1.254)
translate_hits = 6, untranslate_hits = 0
Additional Information:
Dynamic translate 192.168.1.50/1025 to 172.22.1.254/1028
using netmask 255.255.255.255
Phase: 9
Type: NAT
Subtype: host-limits
Result: ALLOW
Config:
nat (inside) 1 192.168.1.0 255.255.255.0
match ip inside 192.168.1.0 255.255.255.0 outside any
dynamic translation to pool 1 (172.22.1.254)
translate_hits = 6, untranslate_hits = 0
Additional Information:
Phase: 10
Type: CAPTURE
Subtype:
Result: ALLOW
Config:
Additional Information:
Phase: 11
Type: CAPTURE
Subtype:
Result: ALLOW
Config:
Additional Information:
Phase: 12
Type: IP-OPTIONS
Subtype:
Result: ALLOW
Config:
Additional Information:
Phase: 13
Type: CAPTURE
Subtype:
Result: ALLOW
Config:
Additional Information:
Phase: 14
Type: FLOW-CREATION
Subtype:
Result: ALLOW
Config:
Additional Information:
New flow created with id 94, packet dispatched to next module
Phase: 15
Type: ROUTE-LOOKUP
Subtype: output and adjacency
Result: ALLOW
Config:
Additional Information:
found next-hop 172.22.1.1 using egress ifc outside
adjacency Active
next-hop mac address 0030.a377.f854 hits 11
!--- The MAC address is at Layer 2 of the OSI model.
!--- This tells the administrator the next host
!--- that should receive the data packet.
Result:
input-interface: inside
input-status: up
input-line-status: up
output-interface: outside
output-status: up
output-line-status: up
Action: allow
03-07-2013 09:32 AM
I'm pretty sure that "FLOW" comes before "ACL"
03-07-2013 09:48 AM
Hi,
I dont think the above packet-tracer commands ACL refers to the typical ACL. It comes later on the packet-tracer output.
Additional Information: MAC Access list
- Jouni
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