James Mason's Blog -or- The Journal of Contemporary Lunacy

Sett ing up a 6to4 tunnel will allow IPv6 (or dualstack) hosts on network s that only have P ublic IPv4 addresses to access sites and services that are available via IPv 6. The main steps are calculating the IPv6 version of your Public IPv4 address ; establishing a 6 to4 tunnel to one of the free I Pv6 relays available; and configuring the local network to route IPv 6 via th e tunnel . Overv iew of the Topolog y       

For a little bit of extra practice before the CCNA exam, I hooked up a small lab with a couple switches bridged to emulated routers (running under GNS3 on the laptop). The reason for the multiple trunks between the switches was to test out Spanning Tree. I was going to setup link aggregation as well, but the 3500XL didn't want to play ball. I found out later that it doesn't support PAgP or LACP , so the method for setting up aggregation is different. VTP and CDP worked properly overly the bridged link - as they should, but I was expecting something to go wrong for some reason (pessimism?). Minicom also played ball with the USB-to-serial adapter (for the console cable), which is always handy too :)

AVGN's latest video has made me nostalgic for all things SNES, so I've drawn up a list of games to revisit. First cab off the rank is Final Fantasy VI, which I've never actually completed due to starting over on multiple platforms. I started on the SNES version, switched to the PS1 release at some point and put most of my hours into the GBA remake (which was very nice but loses a little something on the small screen). I wound up losing track of where I was up to at some point and left it for so long that restarting is probably a decent option anyway. Other games I plan to get to include: Super Mario RPG, Zelda, Super Metroid and Super Mario World.

I thought for a couple days that the shiny new SSD I'd installed would need to be shipped back due to the intermittent controller errors it was reporting. I hadn't had the time to muck around with it until today, when I opened up the case and found the cause was simply the data cable's connector being slightly faulty to the point where it came partially away from the socket due to the cable tension. So, a new cable later and all is well. On the bright side it also reminded me to move it into the SATA3 port and not the SATA2, which would have been a bit of a waste. SATA Spaghetti Now, time to clear up the utter mess I made of the cabling while testing...

Download and install GNS3 – it has a lot of dependencies but the installer contains of all of them. Accept all the defaults for the programs it installs (essentially just keep clicking next). Create Project and Image directories using something simple, like G:\Cisco\Projects and G:\Cisco\IOS. Copy the IOS images (ending in .BIN) to the IOS folder. Open GNS3, cancel the screen asking to open a project and then click Edit then Preferences. Fill in the project and image directory settings by browsing to the folders you just created: Click OK to save and exit.

I hadn't used remote X11 for so long I'd just about forgotten how to go about setting it up, so I thought I'd knock up a quick guide (nothing seems to cement something in my head quite like doing a short howto). Firstly, grab the software you'll need: Download PuTTY and PuTTYGen from the PuTTY Download Page Download and install XMing   Run PuTTYGen and generate a new key (SSH-2 RSA) Save the private key on your client machine and copy the text from public key to ~/.ssh/authorized_keys on the X11 host.

Here's a quick guide to setting up 802.1Q trunking for VLANs on a Debian GNU/Linux box connected to one or more Cisco Catalyst switches, which could then be used as a cheap router replacement. Configuration on the Debian box: Add 8021q to /etc/modules so 802.1Q support is enabled at startup. To install it immediately: # modprobe 8021q Use vconfig to add the VLANs to the interface you'll be using (if vconfig is missing, run apt-get install vlan ): # vconfig add eth0 2 (In the above, eth0 is the physical interface and 2 is the ID of the VLAN) Give the interface an IP. Choose an address in the range you've set aside for that particular VLAN. In this example, VLAN 2 is using 192.168.2.0/24. # ifconfig eth0.2 192.168.2.201 netmask 255.255.255.0

I was lamenting that I'd forgotten far too much about netfilter/iptables so, to jog my memory, I sat down to put together a quick network in VirtualBox. I setup a router/NAT box with one card bridged to my physical network and two cards in two separate Virtual Host-only networks. To keep things nice and distinct, the networks chosen used were 10.0.0.0/24, 172.16.0.0/16 and 192.168.0.0/24. The simple routing script is below (with all firewall rules removed for brevity): #!/bin/bash WAN=eth1 LAN1=eth2 LAN2=eth3 echo 1 > /proc/sys/net/ipv4/ip_forward # flush everything to being with /sbin/iptables -F # setup NAT via $WAN for the two LANs /sbin/iptables -t nat -A POSTROUTING -o $WAN -j MASQUERADE /sbin/iptables -A FORWARD -i $WAN -o $LAN1 -m state --state ESTABLISHED,RELATED -j ACCEPT /sbin/iptables -A FORWARD -i $WAN -o $LAN2 -m state --state ESTABLISHED,RELATED -j ACCEPT /sbin/iptables -A FORWARD -i $LAN1 -o $WAN -j ACCEPT /sbin/iptables -A FORWARD -i $LAN2 -o