Server
Cable Internet – Isolate the Problem
Feb 17th
Image via Wikipedia
After rewiring my entire house the ultimate way to isolate the problem is to put the cable modem directly on the main line. Replace all splitters, and ask the cable company to drop a new main line, and you can feel confident that the problem is no longer in your house. I rewired my entire house, replaced all splitter, then called the cable company. They replaced the splitter outside, and then dropped a new main line. The problem is no longer in my house. My router is loosing its external ip address. So far the cable company said they will compensate us for one months service, if this continues more compensation is warranted.
Every time the internet goes down, this website, my other websites, and all of my email services go offline. I rely on this website to get me through the day when I am at work. What is a day of work when you can blog about things 
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Remote Server Management in Local Facility – LTSP
Feb 13th
I’m using LTSP to manage a server remotely in a local facility. I setup an LTSP server on the host machine, and will place it in an air-conditioned room to preserve longevity. I configured a machine, of much lower power, to PXE boot from the server. There are several nuances to setting up an LTSP server. Once all is done you realize that it is less complicated that is can or needs to be. When things go right there is essentially three step in total. First:
sudo apt-get install ltsp-server-standalone
This installs the works. Then configured dhcp.
sudo nano /etc/ltsp/dhcpd.conf
Config the subnet to the same that you are using on your router. Clearly if your routers local ip is 192.168.0.1 your subnet would be 192.168.0.0. Then set a range. Make sure you turn off the dhcp servers in any and all routers connected to the network. You need the dhcp server on the machine to be the sole and only. Set the “next-server” option to the came local ip address of the server. Then set the rest of the options; domain, default gateway, dns…. Then reboot the server:
sudo /etc/init.d/dhcp3-server restart
Build the clients:
sudo ltsp-build-client
Thats really all there is to it. I’ve found that problems do arise, and instead of trying to fix them just purge all the installed applications and start over.
sudo apt-get remove --purge ltsp-server-standalone ltsp-server xinetd
One time I was stuck because there were two tftp inet servers, openbsd-inetd and inetd-hpa. They were conflicting. Then purge the autoremove function:
sudo apt-get --purge autoremove
Then start over installing ltsp-server-standalone. You can test your ltsp server using VirtualBox. Just like a real machine set the boot sequence to network as the first option. Now hook up a fancy monitor that can support 1920×1080 to the relatively low powered machine in the other room, and remotely manage your server from a pseudo local desktop environment.
Lock Down IP Addresses – SSH and Else
Jan 26th
If you know the IP addresses that will be connecting to your machine, lock them down. Use the hosts.allow file as follows.
sshd : localhost : allow
sshd : 192.168.3. : allow
sshd : 192.168.1. : allow
sshd : ALL : deny
Using sshd : ALL : deny and listing various allow rules blocks everything other than the allowed rules. Therefore using sshd : IP : allow you will be able to connect to the machine from that IP only and everything else will be rejected. This procedure will substantially increase the security of the server.