ASA – 8.3 Upgrade

ASA 8.3 Upgrade – What You Need to Know

First, let’s make sure we get one thing clear, upgrading your ASA from 8.2 to 8.3 is NOT a Minor upgrade!  There are significant internal architectural changes around NAT and ACLs in 8.3.  And, more importantly to you (the customer) are the following:

  1. The NAT CLI commands are completely different from all previous version of ASA
  2. The IP addresses used in the ACLs are different (pre-8.3 versions used the global/translated IPs, whereas 8.3 always uses the real IPs (untranslated)
  3. A new concept of host-based objects was introduced, to allow singular hosts to be referenced by their names (previously, we had the name command, but that was more of a macro-substitution in the show running-config output).

Pre-Requsites to Upgrading #

Many models of the ASA require a memory upgrade prior to upgrading the ASA to version 8.3.  Brand new ASAs from the factory (manufactured after Feb 2010) come with the upgraded memory.  However, if your ASA was manufactured before February 2010, and is one of the models below requiring a memory upgrade, then you will need to purchase the memory upgrade part prior to installing 8.3 on your ASA.

PlatformLicensePre-8.3 Memory Required8.3 Memory RequiredMemory Upgrade Part Number
5505Unlimited (inside hosts=Unlimited)256 MB512 MBASA5505-MEM-512=
5505Security Plus (failover=enabled)256 MB512 MBASA5505-MEM-512=
5505All other licenses256 MB256 MBNo Memory Upgrade Needed
5510All licenses256 MB1024 MBASA5510-MEM-1GB=
5520All licenses512 MB2048 MB *ASA5520-MEM-2GB=
5540All licenses1024 MB2048 MB *ASA5540-MEM-2GB=
5550All licenses4096 MB4096 MBNo Memory Upgrade Needed
5580All licenses8-16 Gb8-16 GbNo Memory Upgrade Needed

* Note:  The maximum memory supported for the ASA-5520 and ASA-5540 is 2 Gb.  If you install 4 Gb of memory in these units, they will go into a boot loop.

How to Determine How Much Memory Your ASA Has #

From the CLI, you can issue the show version | include RAMcommand to see how much memory your ASA has.  In the following example, it is an ASA-5520, with 512 MB of RAM, and therefore would require a memory upgrade prior to installing 8.3 on it.

ASA# show version | include RAM #

Hardware:   ASA5520, 512 MB RAM, CPU Pentium 4 Celeron 2000 MHz

For ASDM users, you can see the amount of RAM in the ASA from the ASDM Home (Device Dashboard) page.

Why Does the ASA Need a Memory Upgrade?

This seems to be a fairly common question with customers.  Why exactly are we requiring a memory upgrade in order to run 8.3?  The reason is simple.  The memory on the ASAs have not been increased since they were originally introduced, yet as the years have gone by new features have been added which require additional memory at boot.  The more memory the base image requires, the less memory there is for things like ACLs, connections, IPSec tunnels, SSL tunnels, etc.  Additionally, as we introduce new features and customers adopt those, they consume additional memory.

Remove nat-control from your ASA Configuration #

nat-control is a legacy feature which was created to help users migrate from PIX 6.x to PIX/ASA version 7.0 and higher.  In PIX 6.x, if you wanted to pass traffic between two interfaces, it was required that you have a NAT configuration which would allow it.  PIX/ASA version 7.0 removed this restriction, and made the behavior like routers.  Which is, ACLs control if traffic is permitted or not.  NAT then becomes optional.  However, in order to preserve the behavior for the PIX customers, if a PIX user upgraded from 6.x to 7.0, then the nat-controlcommand was automatically added to the configuration.  The same is true of customers using the PIX to ASA migration tool.  Thus, there may still be a number of customers with nat-control in their configuration, and who do not need it.

What happens if I remove the nat-control command?

Answer:  Not much.  Removing the command just means that traffic can flow between interfaces without requiring a nat policy.  Therefore, the security policy of what traffic is permitted or denied is defined by your interface ACLs.

What happens if I leave the nat-control command in my configuration?

Answer:  Since 8.3 no longer supports the nat-control command, it will add equivalent nat commands to enforce a policy which requires explicit nat rules to allow traffic to pass between interfaces.  An example is shown below.  Note that the number of these rules increases exponentially with the number of interfaces on your ASA.  Thus, it is highly recommended that if your security policy (ie: ACLs) is used to control what traffic is allowed where, then you should issue no nat-control prior to upgrading to ASA version

8.3.  This will prevent the following nat rules from being created – which will block traffic between interfaces, until a more specific nat policy is defined for that traffic.

pre-8.3 Configuraiton8.3 Configuration
nat-control object network obj_any  

nat (inside,outside) dynamic obj-  object network obj-    host 

object network obj_any-01  
nat (inside,mgmt) dynamic obj- 
object network obj_any-02  

nat (inside,dmz) dynamic obj- 
object network obj_any-03  

nat (mgmt,outside) dynamic obj- 
object network obj_any-04  

nat (dmz,outside) dynamic obj- 
object network obj_any-05  

nat (dmz,mgmt) dynamic obj-

If you forget to issue no nat-control prior to upgrading, then it is safe to remove the all 0’s objects with associated nat rules after the fact.

To view your current nat-control configuration, issue the command show run all nat-control.

How to Upgrade Your ASA to 8.3 #

Upgrading your ASA to 8.3 is the same process as all previous upgrades.  Just copy the image over to the flash, specify the file to boot, and then reboot your ASA.  Upon first boot, the ASA will auto convert your 8.2 configuration into the new syntax for NAT and ACLs required of 8.3.  While your CLI commands will change, your devices security policy will remain the same.

Please note that we only support upgrading to 8.3 from 8.2.  Therefore, you need to be running 8.2 on your ASA prior to upgrading to 8.3.

For ASAs in failover set, we do support upgrading from 8.2 to 8.3 with zero-downtime. 

Note: During the upgrade process, the ASA will save two files on disk.

  1. The current (pre-upgraded) configuration in a file named <version>_startup_cfg.sav  

Example: disk0:/8_2_2_0_startup_cfg.sav

This file will be critical if you need to downgrade your ASA from 8.3 to 8.2 in a future date

  1. Warning messages and Errors encountered during the upgrade process of converting your configuration to 8.3 will be saved in a file named upgrade_startup_errors_<timestamp>.log

Upgrade Paths #

Cisco officially supports upgrading to ASA version 8.3 only from ASA version 8.2.  Therefore, if you are currently running a version of ASA code prior to 8.2, you will need to perform a stepwise upgrade.  Please see the table below:

Current TrainIntermediate UpgradesFinal Train
7.28.0 –> 8.28.3
7.17.2 –> 8.0 –> 8.28.3
7.07.2 –> 8.0 –> 8.28.3

Examples of Configuration Changes in 8.3 NAT #

The NAT CLI configuration for 8.3 is radically different than anything than you may be used to. Therefore, for CLI users, it is recommended you ease into 8.3 with the expectation that you will have to re-learn NAT.  For those who view this as an obstacle, we would recommend that you use ASDM or CSM or some other GUI tool to configure the ASA – as the GUI configuration for 8.3 is largely the same.

That said, for CLI users, please do not upgrade to 8.3 on a Friday night just as you are getting ready to go out of town for the weekend.  Instead, it is recommend that you play with it in a lab (if you have one), or read up on the changes (see Additional Information below) before you upgrade.  Ok, with that said, let’s look at some examples.

NAT Featurepre-8.3 Configuration8.3 Configuration
Static NATstatic (inside,outside) netmask 1 (Preferred) object network obj-   host  nat (inside,outside) static 

Option 2object network server_real  host network server_global  host
!nat (inside,outside) source static server_realserver_global
Dynamic PATnat (inside) 1 (outside) 1 network internal_net   subnet
object network internal_netnat (inside,outside) dynamic
Dynamic NAT with Interface Overloadnat (inside) 1 global (outside) 1 interfaceglobal (outside) 1 network NAT_Pool
range object network internal_net
object network internal_netnat (inside,outside) dynamic NAT_Pool

ACL Changes #

Although the syntax of the ACLs haven’t changed much (just added capabilities for new objects), the significant change is that all IP addresses listed in ACLs which are applied to an interface will be converted (on upgrade) from using global (ie: translated or post-NAT) IP addresses, to using the real IP address.  Let’s look at an example.

In the above Topology, an internal web server (with IP is being protected by an ASA.  Clients on the Internet access this web server by its public IP address:  Prior to version 8.3, the interface ACL would permit traffic to the public IP  But, starting with 8.3 the real IP is used in the configuration.  Please see the configuration examples below.

pre-8.3 Configuration #

static (inside,outside) netmask


access-list outside_in extended permit tcp any host access group outside_in in interface outside

8.3 Configuration #

object network obj-   host   nat (inside,outside) static


access-list outside_in extended permit tcp any host access-group outside_in in interface outside

What to Do If You Run Into Problems with 8.3 #

  1. Call in to the TAC, and they can help you
  2. Check the upgrade_startup_errors_<timestamp>.log on disk0: by using the more disk0:/upgrade_startup_errors_<timestamp>.log 
  3. Downgrade to 8.2 using the downgrade <image> <config> command.  This is IMPORTANT!  You must use the downgrade command, specifying the config file on disk (which the 8.3 upgrade process saved)

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