Tag Archives: Cisco Router

OSPFv3 Lab Featured Image

OSPFv3 for IPv6 Lab: Cisco, Fortinet, Juniper, Palo Alto, Quagga

Similar to my test lab for OSPFv2, I am testing OSPFv3 for IPv6 with the following devices: Cisco ASA, Cisco Router, Fortinet FortiGate, Juniper SSG, Palo Alto, and Quagga Router. I am showing my lab network diagram and the configuration commands/screenshots for all devices. Furthermore, I am listing some basic troubleshooting commands. In the last section, I provide a Tcpdump/Wireshark capture of an initial OSPFv3 run.

I am not going into deep details of OSPFv3 at all. But this lab should give basic hints/examples for configuring OSPFv3 for all of the listed devices.

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S2S VPN FortiGate - Cisco Router w VTI

IPsec Site-to-Site VPN FortiGate <-> Cisco Router

This blog post shows how to configure a site-to-site IPsec VPN between a FortiGate firewall and a Cisco router. The FortiGate is configured via the GUI – the router via the CLI. I am showing the screenshots/listings as well as a few troubleshooting commands.

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fd-wv-fw01.cfg-_172.16.1.1_IPv4IPv6-ds-l2-r1

IPv4 vs. IPv6 Traffic Statistics on Routers

I am very interested in statistics about the usage of IPv6 on Internet routers and firewalls. The problem is, that most routers/firewalls do not have unique SNMP OIDs for IPv4 and IPv6 traffic, but only the normal incoming/outgoing packet counters per interface. Therefore I am using two independent ethernet ports and cables between my outer router and my first firewall, one for IPv4-only and the other one for IPv6-only traffic. Now I have independent statistics for each protocol and can combine them in one summary graph. (Though I know that this will never be a “best practice” solution…)

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OSPF Lab Featured Image

OSPF for IPv4 Test Lab: Cisco Router & ASA, Juniper SSG & Palo Alto

I tested OSPF for IPv4 in my lab: I configured OSPF inside a single broadcast domain with five devices: 2x Cisco Router, Cisco ASA, Juniper SSG, and Palo Alto PA. It works perfectly though these are a few different vendors.

I will show my lab and will list all the configuration commands/screenshots I used on the devices. I won’t go into detail but maybe these listings help for a basic understanding of the OSPF processes on these devices.

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S2S VPN Juniper ScreenOS - Cisco Router w VTI

IPsec Site-to-Site VPN Juniper ScreenOS <-> Cisco Router w/ VTI

And finally: A route-based VPN between a Juniper ScreenOS SSG firewall and a Cisco router with a virtual tunnel interface (VTI). Both sides with tunnel interfaces and IPv4 addresses. Both sides with a real routing entry in the routing table. Great. 😉

(The VPN between those two parties without a tunnel interface on the Cisco router is documented here. However, use the route-based VPN where you can. It is easier and more flexible. Routing decisions based on the routing table. This is how it should be.)

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S2S VPN Palo Alto - Cisco Router w VTI

IPsec Site-to-Site VPN Palo Alto <-> Cisco Router w/ VTI

One more VPN article. Even one more between a Palo Alto firewall and a Cisco router. But this time I am using a virtual tunnel interface (VTI) on the Cisco router which makes the whole VPN set a “route-based VPN”. That is: Both devices decide their traffic flow merely based on the routing table and not on access-list entries. In my opinion, this is the best way to build VPNs, because there is a single instance (the routing table) on which a network admin must rely on in order to investigate the traffic flow.

Note that I also wrote a blog post about the “policy-based VPN” between a Cisco router and the Palo Alto firewall. This here is mostly the same on the Palo Alto side while some other commands are issued on the Cisco router.

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S2S VPN Cisco Router - FritzBox

IPsec Site-to-Site VPN Cisco Router <-> AVM FRITZ!Box

Der Titel sagt eigentlich schon alles: Es geht um das Herstellen eines S2S-Tunnels zwischen einem Cisco Router (statische IPv4) und einer FRITZ!Box (dynamische IP). Ich liste nachfolgend alle Befehle für den IOS Router sowie die Konfigurationsdatei für die FRITZ!Box auf. Für eine etwas detaillierte Beschreibung des VPNs für die FRITZ!Box verweise ich auf diesen Artikel von mir, bei dem ich zwar ein VPN zu einem anderen Produkt hergestellt habe, aber etwas mehr auf die Schritte der Konfiguration eingegangen bin.

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S2S VPN Juniper ScreenOS - Cisco Router

IPsec Site-to-Site VPN Juniper ScreenOS <-> Cisco Router

Similar to all my other site-to-site VPN articles, here are the configurations for a VPN tunnel between a Juniper ScreenOS SSG firewall and a Cisco IOS router. Due to the VPN Monitor of the SSG firewall, the tunnel is established directly after the configuration and stays active all the time without the need of “real” traffic.

I am using the policy-based VPN solution on the Cisco router and not the virtual tunnel interface (VTI) approach. That is: No route is needed on the router while the Proxy IDs must be set on the Juniper firewall. (However, I also documented the route-based VPN solution between a ScreenOS firewall and a Cisco router here.)

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S2S VPN Palo Alto - Cisco Router

IPsec Site-to-Site VPN Palo Alto <-> Cisco Router

This time I configured a static S2S VPN between a Palo Alto firewall and a Cisco IOS router. Here comes the tutorial:

I am not using a virtual interface (VTI) on the Cisco router in this scenario, but the classical policy-based VPN solution. That is, no route entry is needed on the Cisco machine. However, the Palo Alto implements all VPNs with tunnel interfaces. Hence, a route to the tunnel and Proxy IDs must be configured. (I also wrote a guide for a route-based VPN between a Cisco router and a Palo Alto firewall here.)

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Cisco Router Disable DNS Rewrite NAT

Cisco Router: Disable DNS Rewrite ALG for Static NATs

I am using a Cisco router for my basic ISP connection with a NAT/PAT configuration that translates all client connections to the IPv4 address of the outside interface of the router. Furthermore,  I am translating all my static public IPv4 addresses to private ones through static NAT entries. I basically thought, that only the IPv4 addresses in the mere IPv4 packet header would be translated. However, this was not true since I immediately discovered that public DNS addresses are translated to my private IPv4 addresses, too. This was a bit confusing since I have not explicitly configured an application layer gateway (ALG) on that router.

“Google is my friend” and helped me one more time to find out the appropriate solution: The “no ip nat service alg udp dns” keyword to disable the DNS rewrite. (The synonym from Cisco for DNS rewrite is: DNS doctoring.) Here comes a basic example:

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Cisco Router ISP Load Balancing

Basic ISP Load Balancing with a Cisco Router

“We have two independent DSL connections to the Internet and want to share the bandwidth for our users.” This was the basic requirement for a load balancing solution at the customer’s site. After searching a while for dedicated load balancers and thinking about a Do-It-Yourself Linux router solution, I used an old Cisco router (type 2621, about 40,- € on eBay) with two default routes, each pointing to one of the ISP routers. That fits. 😉

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fd-wv-ro01.cfg-172.16.0.1_Fa0-ds-l2

MRTG/Routers2: Adding a Cisco Router

This post shortly explains the process of adding a Cisco router into the monitoring system “MRTG with Routers2” as I explained it here. It gives an example on how SNMP is activated on the router and how the *.cfg file for MRTG/Routers2 is created with the additional values for CPU and memory usage.

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