12 May

Interfaces are important in ASAv failover on VIRL

Failover link on ASAv must be created using interface GigabitEthernet0/8

One reader asked me few days ago following question when he had problem establishing the failover in his lab: “I’ve tried to create ASA failover pair on VIRL and it was not working. I’ve looked through manual and VIRL forum for the solution. I believe that failover is supported configuration on VIRL. I think my configuration is correct, nodes can ping each other but I still cannot establish failover relationship”. Configuration he made was correct except he forgot about one thing – interfaces numbers are important when you setup failover using ASAv.

Cisco VIRL uses ASAv image for virtual firewalls. This is same image that you use in production on ESXi. That means all restrictions applies also to virtual firewall if you run it on VIRL. In this image we must configure failover link using interfaces GigabitEthernet0/8. It’s clearly stated in documentation. If we use any other interface the configuration will be accepted but failover never established.

failover lan unit primary
failover lan interface Fail-link GigabitEthernet0/8
failover replication http
failover link State-link GigabitEthernet0/7
failover interface ip Fail-link standby
failover interface ip State-link standby
failover ipsec pre-shared-key 0 FailoverKey

We also need to remember we can’t configure Active-Active failover. This mode is not supported so we have to stick to Active-Standby model. It’s direct result of lack of support for virtual contexts so remember about it as well.

05 Mar

ASAv on Amazon Web Services – login issues

Have you ever tried to run ASAv image on Amazon Web Services (AWS)? Yes, in Marketplace you will find supported image of this firewall (which is actually great thing because you can run it in BYOB model where you use unlicensed mode for testing the features. Same way as you can do on your ESXi.

Deployment is easy with the creator of EC2 instance, just few clicks and there it is. Except small problem – on latest release of I was not able to connect to management interface via SSH. It should be possible by using key assigned to instance during creation but no matter what I’ve done it always asked for password.

There is small but nice workaround of this problem that also enables HTTPS access to ASAv. During the instance deployment we should put zero-day configuration that will be implemented on ASA. In documentation we even have proposal on such config which we further modify by adding HTTP/HTTPS access, additional user account, enable password and aaa local authentication.

The final zero-day configuration should look as below

interface management0/0
nameif management
security-level 100
ip address dhcp setroute
no shut
same-security-traffic permit inter-interface
same-security-traffic permit intra-interface
crypto key generate rsa modulus 2048
http server enable
http management
ssh 0 0 management
ssh timeout 30
username admin nopassword privilege 15
username admin attributes
username cisco password cisco privilege 15
enable password cisco
aaa authentication ssh console LOCAL
aaa authentication http console LOCAL
service-type admin 

This way we will be able to connect to ASAv instance via ssh/http using local accounts.

31 Oct

Cisco ASA REST API – Part II: How it’s really working?

First published: 31/Oct/2016
Last update: 31/Oct/2016
ASA REST API version: 1.3.2

In previous chapter we configured ASA to support REST API interface and executed simply query. It was nice to see something in action but let’s now think how it’s working and how we can use it.

Every operation you can do using REST API you can also execute via traditional CLI commands or simplifying your life a little by using ASDM. Many of parameters you can fetch using SNMP or from syslog. So is it just another way to manage your device? Answer is both yes and no. Yes, because it is way of managing the device. No, because using REST API you have to stop thinking that you configure service but you are programming it usually as a part of bigger script or application.


REST API on ASA side is small plugin loaded into device flash memory and then activated using CLI.



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