Sunday, July 17, 2011

Tweaking firefox

1) Have a lot of tabs? Worried about FF slowing your machine to a crawl on a restart? Change FF so it only keeps the active tabs in memory. And at startup it only loads the active tab on each window.

Visit the URL about:config, proceed past the warning, and then set
browser.sessionstore.max_concurrent_tabs
to 0 (zero) by double clicking on that value (you can search for "max" first to narrow the list of variables).

2) Install the add-on "Noscript". This add on is an inconvenience initially and occasionally afterwards, as it is a Javascript blocker. When you visit a site you trust for the first time, you'll have to let Noscript know that you want to allow JS from that site. But if you inadvertantly visit or get redirected to a shady site, it will block the JS saving your rear. Choose "Tools" -> "Add-ons" and then search for "Noscript". Install it and restart the browser. By default it will install a little icon in your address bar.

Saturday, June 11, 2011

Airlink ar410w is not compatible with DD-WRT

Having just installed DD-WRT and then Tomato on a new Netgear 3500L, it was exciting to run a real OS on a router. I also had an old Airlink 101 AR410W still running, but upon checking it only supported WPA TKIP, not the newer WPA2 AES (avoid TKIP). I vaguely recall WPA being not that secure, and wanted WPA2. But there is no firmware upgrade from the manufacturer product page. I realized Tomato only supports a small subset of routers using modern CPUs, but could I upgrade to DD-WRT as it supports a fair number of routers.

A bit of hunting around shows that
  1. This router is the same as the DLink DI-624 which is specifically not supported by DD-WRT, in large part because it only has 1MB of flash, and you need 2MB just to run the mini version and 4MB to run anything full featured.
  2. The specs are it has a Atheros 2313 CPU + radio, Marvell 88E6060 ethernet switch, and Macronix/AMD 29LV800BTC-90 1MB Flash.
  3. The FCC ID from the label is: O7J-WLRT2454-QAO
In any case, it is clear I cannot install DD-WRT on this pre-2006 router.

Sunday, January 2, 2011

Changing the user id of an existing user

There is an existing user Adam with user id 1000 that you want to change to user id 2345.
Adam is the only user on the system and is an admin, of course. Adam also has an encrypted home directory.

1) Log in as Adam.
2) Create a new admin user, say call Newsome.
3) Log out as Adam and log in as Newsome. Ensure that "sudo id" succeeds as Newsome in case you mess something up with Adam's login
4) Run System -> Administration -> Users and Groups
5) Choose Adam, then Advanced Settings. In the Advanced User Settings window choose "Advanced" and then change the user id.
6) Hit "OK" and then "Close" on the User Settings tab.
7) Run "grep Adam /etc/passwd" and verify the new user id is 2345.
8) Run "ls -ln /home/Adam" and verify the owner id is 2345.
9) In a terminal go to and run "sudo chown Adam /home/.ecryptfs/Adam"
10) In a terminal, login as Adam and verify that all the files in the home directory exist.

Ubuntu note: Normal user start at 1000. Anything below that is considered reserved, but you are free to use those IDs. On the login screen, if your ID is below 1000, you'll have to choose "Other user" (or something like that) and enter your username, which is arguable slightly more secure but more annoying.