Wednesday, April 8, 2015

vMotion Fails - Failed to connect to remote host. Network unreachable.

When migrating a VM using vMotion, the migration may stall at 14% and eventually fail with the following error:

Migration [xxxx:xxxx] failed to connect to remote host <x.x.x.x> from host <y.y.y.y>: Network unreachable.

Usually this is a pretty straightforward fix: correct whatever network issue is preventing communication between the vmkernel ports.  However, I recently encountered an issue where the network was configured properly, traffic was flowing, and vMotion still failed.

Everything with the multi-NIC vMotion config checked out:
  • Two separate VMkernel ports on the relevant vSwitch with IPs on the same subnet.
  • One vmnic active and one standby for each VMkernel port.
  • Active/standby adapters on the second VMkernel port were the inverse of the first.
  • vMotion enabled on the vMotion VMkernel ports.
  • 9000 MTU on each vSwitch and VMkernel port
  • 9000 MTU on the relevant switch and switchports.
  • Relevant switchports tagged for the appropriate VLAN.

(The configuration is pretty straightforward, as outlined in the VMware KB:

Tuesday, March 31, 2015

ASA Remote Access User Prevent SSH Access

When configuring a remote access VPN on an ASA, there are times when an external authentication server (RADIUS, TACACS+, etc) is not available.  In this case, the local AAA database can be used:
asa01(config)# username vpnuser password p@ssw0rd privilege 0
asa01(config)# username vpnuser attributes
asa01(config-username)# service-type remote-access
asa01(config-username)# exit
You might think that specifying privilege 0 and service-type remote access as shown above would be enough to prevent this user from logging in through SSH.  However, this may not be the case.  Let's look at the following example:
asa01# sh run user vpnuser
username vpnuser password jpCK6VfivhvBp0Pn encrypted privilege 0
username vpnuser attributes
 service-type remote-access
asa01# sh run aaa
aaa authentication ssh console LOCAL
aaa authorization exec LOCAL
With this configuration, it is still possible for "vpnuser" to log in through SSH:
vpnuser@asa01's password:
login as: vpnuser
vpnuser@asa01's password:
Type help or '?' for a list of available commands.
This is possible because the above configuration only specifies AAA authentication, not authorization.  Therefore the local user account's password is checked against the local database, but no check is performed to determine whether or not this local user is authorized for EXEC shell access.  This behavior can be changed by enabling management authorization with the following command:
asa01(config)# aaa authorization exec LOCAL
Now if we attempt to log in with this same account, the login will fail:
login as: vpnuser
vpnuser@asa01's password:
Access denied
vpnuser@asa01's password:

The ASA configuration guide goes into more detail about this feature here:

Saturday, January 10, 2015

Choosing an ExtremeXOS Software Release

When updating ExtremeXOS, it is important to choose your software release carefully.  The newest builds may contain new features that are not yet stable.  I learned this the hard way.  The Extreme support portal currently does not label their software builds with anything that indicates what is a stable build and what is may contain new unstable features.

Thursday, January 8, 2015

Extreme Networks EXOS Cheat Sheet

After working in primarily Cisco or Cisco-esque CLIs, ExtremeXOS can have a bit of a learning curve.  At the time of this post, Extreme Networks' documentation is almost entirely in PDFs.  In my opinion, these are a bit of a pain to navigate and are not well indexed by search engines.

This post is meant to serve as a basic EXOS cheat sheet.  It is by no means meant to be a configuration guide or thorough command reference.  I will update this post periodically to add additional commands.

update: I reached out to Extreme regarding their documentation (I work for a partner), and it turns out they already have an EXOS cheat sheet, so my channel SE sent it over.  I was not able to find this document anywhere on Extreme's site.  However, an Extreme SE confirmed this document is public, so here it is:  EXOS Quick Guide - Cheat Sheet.  I may still update this page on occasion, but Extreme's document is more complete.

Monday, January 5, 2015

HOWTO: Basic Cisco ASA AnyConnect VPN 8.2(5)

A while back I posted a how-to for configuring AnyConnect in ASA version 8.3+.  I recently received a request to post the 8.2(5) configuration, so here it is.  The example below uses split tunneling and local authentication.  For RADIUS authentication, see this post.

Before beginning, verify you have the AnyConnect essentials license (without this license, only two simultaneous sessions are permitted).
asa# sh ver | inc AnyConnect
AnyConnect Premium Peers          : 25             perpetual
AnyConnect Essentials             : 25             perpetual
AnyConnect for Mobile             : Enabled        perpetual
AnyConnect for Cisco VPN Phone    : Enabled        perpetual