Lessons Learned: Overriding routing in Cisco ASA

While at a client this week, I ran across a fundamental change in post 8.3 cisco ASA routing logic which blindsided me for a while. The scenario was that after changing some VPN tunnel endpoints and hence changing subnet locations, we started seeing errors in syslog along the lines of TCP session torn down, "no … Continue reading Lessons Learned: Overriding routing in Cisco ASA

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Palo Alto firewall and BGP routing

Objective: This article will record the steps taken and scenarios simulated during BGP lab sessions involving the PA 5020. Scenario 1: A single ISP, with an eBGP peering between the PaloAlto and a CISCO ISP router.   The above network diagram shows the basic setup. The objective of this scenario is to advertise the “public” … Continue reading Palo Alto firewall and BGP routing

KVM & BRCTL in Linux – bringing VLANs to the guests

I recently had the opportunity to setup a KVM machine running on a Centos machine. Tools such as Virtual Machine Manager (VMM) help immensely in the provisioning and administration of virtual machine guests within KVM, and bring the KVM solution on par with other solutions such as Xen, VMWare and VirtualBox. Networking is one of … Continue reading KVM & BRCTL in Linux – bringing VLANs to the guests

Windows L2TP split tunnelling using CMAK

by Default, the in-built windows L2TP client will attempt to tunnel all internet traffic over an L2TP VPN connection. This can of course be disabled to achieve a low level of split tunnelling: Right click on the VPN adapter > properties > TCP/IP settings > Advanced. Clear the “use default gateway on remote network” It’s … Continue reading Windows L2TP split tunnelling using CMAK

PathPing : the forgotten latency tool

One of the biggest network troubleshooting questions has to be “why is my site loading so slow?” (and other related latency questions). A very useful and underutilised tool is built right into the windows OS. This tool is a relative of traceroute and uses ICMP to calculate the latency introduced at different hops along the … Continue reading PathPing : the forgotten latency tool

Nugget Post : IPv6 Addresses

When studying IPv6 I always find it difficult to keep track of the different IPV6 address types. Here’s a handy table that summarizes the different address prefixes:

Networking tips in VMWare ESX server

Two notes to make here : regarding VLANs and regarding virtual routers ################################################################################## VLANs Ran across a very useful nugget of information. VMWare ESX server allows you to define virtual switches, but it also allows you to assign a particular switch a VLAN ID. In other words, any traffic that originates from virtual machines that … Continue reading Networking tips in VMWare ESX server