October 31, 2005
Keeping bad guys away from root.
While going through my server logs, I found hundreds of attempts to log into root over ssh - brute force password guessing attacks.
Popular ways of locking down the server are:
* Disabling root's ability to log in over ssh - But I need to be able to do this, both for backups and for some remote config changes.
* Only allowing key based authentication - But sometimes I need to be able to connect to my server from my cell phone.
* Only allowing access to the box from certain IPs - But I often need to connect to my box from all over the world.
My solution was to require key based authentication for root logins. This defeats the automated guessing at root's password, yet does not hamper my automated backups. In sshd's config file you set the following to do this:
PermitRootLogin without-password
Num Lock.
I set up a new server for a fellow. But he could not log into it. After trying repeatedly walking him through the process over IM, we gave up for the day.
After much thinking, it occurred to me that perhaps he had Caps-Lock on. A phone call later, we discovered that it was not Caps-Lock that was causing the problem - it was Num-Lock!
So remember people: When folks' password won't work, check both Caps-Lock and Num-Lock.
October 22, 2005
October 20, 2005
Trivia.
- There are leap seconds. Yet another thing to think of when programming complicated, real time stuff.
- You can put linux in your linksys wireless router with OpenWrt
- Rule #11. Chronic or prolonged sleeping that disturbs other patrons or staff is not permitted. -- My local library rules.
A common code.
The Ethnologue is a database of the worlds languages. You can look up some random language like Tunni in Somalia.
You can find out that people that speak english are often "Island, plains, hills. Deciduous forest. Industrial workers, fishermen; craftsman. Christian."
October 08, 2005
Stanford Wins!.
Booyeah! Standford's robot has crossed the finish line!
Even though it is possible for another bot to turn in a faster time, it's not that likely. Regardless, autonomous vehicles have been able to handle 131 miles.
Stanford Passes Red Team.
Just passed the 102 mile mark, Stanford got to pass Red Team. YES YES YES!
Of course we still may see Stanford drive off a cliff in the mountains, but for now things are looking good.
100 mile mark.
Stanford and Red Team Two continue battling it out with only 30 miles to go.
"Alice", the fifteen passenger van fabled for stylishly chewing up a row of hay bales during the NQE, is out, having tried to run down the media.
"The vehicle's main approach is to exploit the methodical perseverance of its namesake," says the team of "Desert Tortoise". They were not joking, in 5 hours and 20 minutes he's driven just 13 miles.
I've finally found a good site - TG Daily, therefore I'll stop covering the race here. Other than to cheer when the first vehicle finishes the challenge. Or when the 27,800 pound TerraMax accidently drives over a stopped, eliminated competitor.
Drop'n out..
The desert claimed four eliminated in the last few minutes. Princeton's GMC truck, Cornell's custom desert racer, and monsertmoto's four wheeler all were knocked out 19-21 miles from the starting line. One of the front runners is also down, Team Dad's truck (brains hand coded in assembly language) is out 38 miles down the course. (more that five times further than anyone got last year.)
The two red team vehicles, and stanford are still going strong in the front. Watching them makes this challenge look easy, but as strong teams are being elimninated behind them, you can see how much thinking really went into the race leaders.
Update: Minutes later, UCLA's Dodge Ram is out of the race, with 34 miles covered.
One hour so far.
One hour into the grand challenge. Red Team Too has traveled 25 miles. Stanford, starting 5 minutes behind has traveled 23 miles. Three contestants have been eliminated so far.
The best place to see photos of the vehicles during qualifying is the flicker tag "Darpa". (The above photos are by John Gale)
Red Team has quite the advantage - they are racing two vehicles, so when a random freak accident happens, they will still have another vehicle in the race.
In contrast to Red Team's caution and careful dealing with risk. Team Stanford has been pushing the limits during the qualifying. I'm betting "Stanly" will attempt to pass "H1ghlander"
Darpa Grand Challenge.
The first bots are now running the Darpa Grand Challenge, a 100 and something mile autonomous trek through the desert, tunnels, and mountain switchbacks. Live updated map on the site.
I'm loving it!
