For years I got my dad's old computers as hand-me-downs. He helped me with a few upgrades to make them a little more usable. Of course this presented a strong motivation to learn about Linux.
I didn't get a laptop until my junior year of high school. It was a big Christmas present. Nothing fancy, a refurbished Toshiba, but it was awesome. A little slow though. The next summer I saved up enough to buy a nicer Dell, which lasted until the screen was shattered (I still don't know how).
By all means make sure kids have computers and tools, especially if they're interested in more than just games. Laptops are a little more fragile and expensive, though, and I think parents should hold off until they know the laptop will be taken care of.
SpaceShipOne cost about $20 million. Insanely cheap for a project of that type. I think that combining NASA's funding with the engineering talent and attitudes at Scaled could produce some amazing results. SS1 was not an orbital vehicle, but given sufficient resources, I'm confident they could solve the necessary problems and build one.
The thing that impresses me about Scaled is their "make it happen" attitude. They have faith in their abilities and produce some amazingly cool stuff. Given the resources, I'm confident that a shop like that could build a safer orbital vehicle.
It's probably illegal to use such an antenna, unless you are an amateur radio operator (just need a Tech license, REALLY easy to get).
But possession? It is absurd to say that is illegal. Any metal object can be used as an antenna. I don't think the FCC has any rules whatsoever about wiring up connectors to Pringles cans, unless you then use it to generate unlicensed RF fields.
In California, I've thought a good response might be "I was moving at a reasonable, safe, and prudent speed as required by the Basic Speed Law."
Might piss off the cop a bit, but it does not admit guilt.
California lets you void one ticket every 18 months by taking traffic school. It's inconvenient and costs more than the ticket, but you don't get points on your license (and hence your insurance doesn't go up). If you have more than one ticket in a year and a half, judges will often let you do traffic school anyway.
UNIX Network Programming is an absolute must-have for anyone who wants to learn network coding. It explains everything you need to know for both clients and servers, discusses the various threading and forking models servers use, covers pthreads, and touches on lots of other essential subjects.
Later in the book Stevens goes on to explain the protocols in depth, developing ping and traceroute clients using raw sockets. With help from this chapter I successfully scared the crap out of a nearby friend by blasting his firewall with forged IP packets.:)
UNP comes off my shelf every time I have to write network-related code.
Ham radio is not exactly in its "death throes". I used to go to Georgia Tech's excellent amateur radio station (W4AQL) at random hours of the day (between classes often) and have unscheduled chats with people all over the world. They're out there. Maybe not as many as there used to be.
HFpack (http://www.hfpack.com/) is a great source of HF contacts, with an emphasis on portable and low power operation. They have a very active and enthusiastic mailing list.
Hams were a huge help after 9/11. They provided local communication networks for ground personnel with very good success. 9/11 was definitely a success story for ham radio. I don't know if they were useful in the London situation, but if I'd been there with my equipment, I certainly would have made it available.
The cell phone outages in London were due to a temporary overload as opposed to missing infrastructure. If the attacks had damaged the phone network, I strongly suspect British hams would have been out en force. But it's also worth noting that most of the HF ham activity in the UK probably takes place in the countryside. Most city hams don't have HF gear, since the antennas are so big and the neighbors usually object to the towers.
Digital modes are neat, but when I was really into radio I was much more interested in learning about propagation, atmospheric conditions, antennas, feed line attenuation, and so forth. The basics of radio. I didn't really care what was going over the radio. Our station ran a digipeater as a service to the local area, but that's about it for digital. I tried Hellschreiber and RTTY a few times for fun. They were neat, but I don't think I ever had a QSO, other than receiving the ARRL's daily RTTY announcements.
I'm going to go buy some of the pineapple extract (bromelain) tonight and start taking it daily.
I have a bad case of melanoma (stage 4), and while there's still some hope in traditional treatments and clinical trials, I need every advantage I can get. If bromelain slows the growth of the tumors even a little, it's a huge help in combination with the other things I'm taking. And if it doesn't help, it probably won't do any harm. It's just natural pineapple extract, and it's been consumed for years.
I'm taking artemisinin (sweet wormwood extract) for similar reasons, though I do have to be careful with my dose of that because it's somewhat hard on the liver. I'm also waiting for an order of Vitamin B17 (amygdalin/laetrile) to arrive. The latter was somewhat hard to track down because of a stink the FDA raised about it a few years ago.
Dietary supplements alone won't cure me, but they just might help, and as such it would be ridiculous for me not to try them.
An automatic banjo and guitar. They sounded very good, but obviously somewhat mechanical. The mechanism seems to be very similar to what the Georgia Tech people came up with.
I don't know why someone brought this to an aircraft show, but it was fun to watch.
I'm not suggesting that anyone do this to steal service from a disabled account. I just find it interesting that disabled connections often allow ICMP to go through.
Your network does it differently than other networks I've seen. Disabled accounts at Georgia Tech can still pull DHCP (I think), but our IPs are effective static anyway.
(I was at GT several years ago. Their routers were cranky and would disconnect you for all sorts of reasons, such as changing your MAC address without dropping link. I actually had a legitimate reason to do that once, but the router thought I was trying to hack it and I had to get the office to turn my connection back on.)
Often when Internet providers disable your cable/DSL/LAN connection for security or billing reasons, they just block TCP and UDP but leave ICMP available. I've observed Georgia Tech's ResNet to do this, and reportedly Adelphia's cable ISP does the same. You can ping to your heart's content, but can't send data.
Except that you can.
A ping packet (ICMP echo request) can have a completely arbitrary payload. You can put any data you want there. You could even tunnel IP inside it. You would have to have to have a friendly server on the outside to receive these packets and forward the contents, but that's easily done.
This trick might also be useful for tunnelling past content filters. I don't think any of them scan ICMP packets.
I'm writing a simple userspace IP stack (gets packets from the tun/tap interface), and I intend to try this out once it's a bit more mature.
-John
Re:ICMP flaw #1 on Linux: it's in the kernel
on
Examining ICMP Flaws
·
· Score: 4, Informative
Yes... it could be done outside of the kernel. The problem is that it's basically a required component of IP (the two interact closely). IP uses ICMP to report errors, for instance. If ICMP were in a user process, it would have to jump the kernel/user boundary every time, which could become very expensive.
ICMP really isn't a server. It's a protocol for performing odd tasks that don't quite belong inside IP itself but that are more or less essential for it to function. 'ping' is just one of about 16 message types ICMP supports. The others involve routing, destination unreachable messages, source quench ("slow down!"), etc.
I think a better design would be to have the entire networking subsystem in userland.
Incidentally, my current project is writing a tun/tap-based IP stack entirely in C#. It's mostly for fun, but when it's finished it'll be a complete userland networking subsystem. (Current status: decodes and defragments IP packets, starting to implement ICMP.)
I think it has more to do with intent. If your goal is to design a program or build a network to accomplish a certain task, that is engineering. But if your goal is to make an impression on the viewer, to say something, to induce emotion, to do something other than just run network cables or perform a calculation, then that's art. If it also happens to be a usable program or network, then it might be functional art.
Look at the demoscene. For many years programmers have created demos, which are generally ten minute graphical presentations set to music. They're sort of like music videos. The good ones take a huge amount of skill to create, both in coding and design. A good demo has aesthetic and often musical value and has a strong effect on the viewer. Demos are definitely art; they just happen to involve a great deal of technical skill as well.
I bothered to track down the prices a while back, and they were INSANE. $20k was around their low end, if I recall.
Re:Wow, look at all the MS haters ...
on
Effective C#
·
· Score: 1
GNU Mono is also a great place to start if you want a free C#/.NET environment. I'm using it to develop in C# on my Powerbook, and it's been smooth sailing so far. I've been impressed with how quickly some of my apps have come together.
C# is a nice language. A very refreshing change of pace from C++..NET is a pretty neat platform, to the extent that it is open and portable. I don't care much for the Windows-specific aspects of it of course.
The ID provisions are certainly debatable either way. The disturbing thing is that they never were debated. This was stuck onto an unrelated guaranteed-to-pass bill and came into law despite many people's reservations. This is an extremely sleazy tactic.
I could buy a PSP and a game... or I could spend the same amount on 18 additional games for my Gameboy Advance.
The PSP's screen is beautiful, and the analog controller is most welcome. I played a friend's briefly this morning, and I was very impressed. I held the screen close and felt immersed in the game environment in a way that I haven't ever experienced with a handheld. But I am not at all convinced that, on average, PSP games are more than twice as fun as GBA games (they are twice as expensive).
Portable gaming is different from console or computer gaming. Portable games need to be quick to start and quick to end. Good graphics and music help, but they are not nearly as important to the overall experience as they are on a console. Frogger's Adventures, Advance Wars, and even ports of old NES games such as Zelda and Metroid are excellent handheld games because you can get into them quickly, have fun, and put them down on short notice. The media experience isn't stunning, but it is sufficient, and the gameplay is compelling.
The Gameboy Advance SP is compact, rugged, and relatively cheap ($80). Games are also cheap ($15-20). The batteries last a long time. There is a nice backlight. It fits easily in a pocket and will probably survive the ensuing beating. The system is no longer cutting edge, but I contend that it is still the best all-around handheld gaming system out there, considering price, games, and overall fun.
Minor GBA gripe: why are the power connector and headphone jack on the same plug? You can't use headphones while you're on AC power. And why couldn't they include a normal headphone jack? I had to buy special headphones just for the GBA.
The Nintendo DS is just an atrocity. What were they thinking? Wireless multiplayer is nice, and the dual screens are neat in some cases (Advance Wars comes to mind), but otherwise the DS seems like an awkward frankentoy.
My problem with Apple's DRM has nothing to do with paying for songs. I've bought quite a lot of music from the iTunes Music Store. My problem arises when I want to transfer my music to a new machine and can't play it without first getting permission from Apple, and can't remember my music store password because I haven't bought anything for a while. Or when my hard drive crashes and their DRM measures get in my way when I try to rebuild my music library. (The iTMS doesn't let you re-download music you've already bought.)
But thankfully JHymn and a shareware iPod recovery utility fixed all of that, and my iTunes music is now DRM-free. So if the iTMS ever goes under (less probable things have happened) or something unfavorable happens to Apple, my investment won't be lost.
I will avoid DRM whenever I can. It reduces the value of the product and causes needless frustration.
Alright, so just be sure that the Flash player you develop using this spec also happens to be able to export at least one valid SWF file. Then it's a product that creates SWF, that just happens to also be able to play it.
But if you do ever end up with a case of melanoma, don't throw up your hands and panic. My case is in a partial remission, and there's a good chance it'll stay that way until a complete cure is available. (Which, at the current rate of research, might be sooner rather than later.)
Chemotherapy is very nasty, but it did stop my tumors from growing. I'm currently on a much less nasty maintenance treatment that will hopefully keep them that way. I'll gladly live with daily interleukin-2 shots and a couple of nights on an IV every few months if it means I won't be eaten alive by tumors.
Georgia Tech used social security numbers all over the place for a long time, but last year someone rattled the right chains and got the entire system switched over to GTID numbers. It was a huge pain in the ass, but they get props for pulling it off.
It used to be BAD. You could stand by the computer lab printer and collect physics homework printouts with social security numbers in the headers.
Most of these systems were implemented in a time when identity theft was not nearly the high-profile problem it is today. Using SSN's wasn't considered bad. Once a big system like that is in place, it's really hard to change. (I suspect the legal department had something to do with getting Georgia Tech to switch.)
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I don't think it would be wise to show kernel memory management code to a child in the first place. :) It does tend to be pretty gnarly.
PPC code actually doesn't look that bad in the end. Be sure to turn on your sarcasm filter when reading Linus.
-John
For years I got my dad's old computers as hand-me-downs. He helped me with a few upgrades to make them a little more usable. Of course this presented a strong motivation to learn about Linux.
I didn't get a laptop until my junior year of high school. It was a big Christmas present. Nothing fancy, a refurbished Toshiba, but it was awesome. A little slow though. The next summer I saved up enough to buy a nicer Dell, which lasted until the screen was shattered (I still don't know how).
By all means make sure kids have computers and tools, especially if they're interested in more than just games. Laptops are a little more fragile and expensive, though, and I think parents should hold off until they know the laptop will be taken care of.
And be sure to get the extended service plan.
-John
SpaceShipOne cost about $20 million. Insanely cheap for a project of that type. I think that combining NASA's funding with the engineering talent and attitudes at Scaled could produce some amazing results. SS1 was not an orbital vehicle, but given sufficient resources, I'm confident they could solve the necessary problems and build one.
The thing that impresses me about Scaled is their "make it happen" attitude. They have faith in their abilities and produce some amazingly cool stuff. Given the resources, I'm confident that a shop like that could build a safer orbital vehicle.
It's probably illegal to use such an antenna, unless you are an amateur radio operator (just need a Tech license, REALLY easy to get).
But possession? It is absurd to say that is illegal. Any metal object can be used as an antenna. I don't think the FCC has any rules whatsoever about wiring up connectors to Pringles cans, unless you then use it to generate unlicensed RF fields.
This cop is clueless. Ignore him.
-John (AE6NK)
In California, I've thought a good response might be "I was moving at a reasonable, safe, and prudent speed as required by the Basic Speed Law."
Might piss off the cop a bit, but it does not admit guilt.
California lets you void one ticket every 18 months by taking traffic school. It's inconvenient and costs more than the ticket, but you don't get points on your license (and hence your insurance doesn't go up). If you have more than one ticket in a year and a half, judges will often let you do traffic school anyway.
Except that many other compilers (MS VC++, ICC, etc) outperform GCC by a significant margin.
GCC will improve, especially with the new infrastructure in the 4.x release. But if you care about performance, GCC is probably not the best route.
GCC's main strength is portability.
-John
UNIX Network Programming is an absolute must-have for anyone who wants to learn network coding. It explains everything you need to know for both clients and servers, discusses the various threading and forking models servers use, covers pthreads, and touches on lots of other essential subjects.
:)
Later in the book Stevens goes on to explain the protocols in depth, developing ping and traceroute clients using raw sockets. With help from this chapter I successfully scared the crap out of a nearby friend by blasting his firewall with forged IP packets.
UNP comes off my shelf every time I have to write network-related code.
-John
Ham radio is not exactly in its "death throes". I used to go to Georgia Tech's excellent amateur radio station (W4AQL) at random hours of the day (between classes often) and have unscheduled chats with people all over the world. They're out there. Maybe not as many as there used to be.
HFpack (http://www.hfpack.com/) is a great source of HF contacts, with an emphasis on portable and low power operation. They have a very active and enthusiastic mailing list.
Hams were a huge help after 9/11. They provided local communication networks for ground personnel with very good success. 9/11 was definitely a success story for ham radio. I don't know if they were useful in the London situation, but if I'd been there with my equipment, I certainly would have made it available.
The cell phone outages in London were due to a temporary overload as opposed to missing infrastructure. If the attacks had damaged the phone network, I strongly suspect British hams would have been out en force. But it's also worth noting that most of the HF ham activity in the UK probably takes place in the countryside. Most city hams don't have HF gear, since the antennas are so big and the neighbors usually object to the towers.
Digital modes are neat, but when I was really into radio I was much more interested in learning about propagation, atmospheric conditions, antennas, feed line attenuation, and so forth. The basics of radio. I didn't really care what was going over the radio. Our station ran a digipeater as a service to the local area, but that's about it for digital. I tried Hellschreiber and RTTY a few times for fun. They were neat, but I don't think I ever had a QSO, other than receiving the ARRL's daily RTTY announcements.
-John
Coumadin, as in warfarin sodium, the powerful blood thinner? That's big pharma, I believe. I doubt they'd axe it.
And there's a lot of money behind Advil, as well as public loyalty. Banning it would cause a serious fallout.
I don't know about trytophan, but I use melatonin when I need a sleep aid, and it works very well.
-John
I'm going to go buy some of the pineapple extract (bromelain) tonight and start taking it daily.
I have a bad case of melanoma (stage 4), and while there's still some hope in traditional treatments and clinical trials, I need every advantage I can get. If bromelain slows the growth of the tumors even a little, it's a huge help in combination with the other things I'm taking. And if it doesn't help, it probably won't do any harm. It's just natural pineapple extract, and it's been consumed for years.
I'm taking artemisinin (sweet wormwood extract) for similar reasons, though I do have to be careful with my dose of that because it's somewhat hard on the liver. I'm also waiting for an order of Vitamin B17 (amygdalin/laetrile) to arrive. The latter was somewhat hard to track down because of a stink the FDA raised about it a few years ago.
Dietary supplements alone won't cure me, but they just might help, and as such it would be ridiculous for me not to try them.
-John
I took this picture at the AOPA Expo in Long Beach last year:
1 =L&size=S
http://overcode.yak.net/7.sizes@100_0649.jpg?size
An automatic banjo and guitar. They sounded very good, but obviously somewhat mechanical. The mechanism seems to be very similar to what the Georgia Tech people came up with.
I don't know why someone brought this to an aircraft show, but it was fun to watch.
-John
I'm not suggesting that anyone do this to steal service from a disabled account. I just find it interesting that disabled connections often allow ICMP to go through.
Your network does it differently than other networks I've seen. Disabled accounts at Georgia Tech can still pull DHCP (I think), but our IPs are effective static anyway.
(I was at GT several years ago. Their routers were cranky and would disconnect you for all sorts of reasons, such as changing your MAC address without dropping link. I actually had a legitimate reason to do that once, but the router thought I was trying to hack it and I had to get the office to turn my connection back on.)
-John
Often when Internet providers disable your cable/DSL/LAN connection for security or billing reasons, they just block TCP and UDP but leave ICMP available. I've observed Georgia Tech's ResNet to do this, and reportedly Adelphia's cable ISP does the same. You can ping to your heart's content, but can't send data.
Except that you can.
A ping packet (ICMP echo request) can have a completely arbitrary payload. You can put any data you want there. You could even tunnel IP inside it. You would have to have to have a friendly server on the outside to receive these packets and forward the contents, but that's easily done.
This trick might also be useful for tunnelling past content filters. I don't think any of them scan ICMP packets.
I'm writing a simple userspace IP stack (gets packets from the tun/tap interface), and I intend to try this out once it's a bit more mature.
-John
Yes... it could be done outside of the kernel. The problem is that it's basically a required component of IP (the two interact closely). IP uses ICMP to report errors, for instance. If ICMP were in a user process, it would have to jump the kernel/user boundary every time, which could become very expensive.
ICMP really isn't a server. It's a protocol for performing odd tasks that don't quite belong inside IP itself but that are more or less essential for it to function. 'ping' is just one of about 16 message types ICMP supports. The others involve routing, destination unreachable messages, source quench ("slow down!"), etc.
I think a better design would be to have the entire networking subsystem in userland.
Incidentally, my current project is writing a tun/tap-based IP stack entirely in C#. It's mostly for fun, but when it's finished it'll be a complete userland networking subsystem. (Current status: decodes and defragments IP packets, starting to implement ICMP.)
-John
I think it has more to do with intent. If your goal is to design a program or build a network to accomplish a certain task, that is engineering. But if your goal is to make an impression on the viewer, to say something, to induce emotion, to do something other than just run network cables or perform a calculation, then that's art. If it also happens to be a usable program or network, then it might be functional art.
.
Look at the demoscene. For many years programmers have created demos, which are generally ten minute graphical presentations set to music. They're sort of like music videos. The good ones take a huge amount of skill to create, both in coding and design. A good demo has aesthetic and often musical value and has a strong effect on the viewer. Demos are definitely art; they just happen to involve a great deal of technical skill as well.
Two good demoscene-related sites are http://www.ojuice.net/ and http://www.scene.org/
-John
I bothered to track down the prices a while back, and they were INSANE. $20k was around their low end, if I recall.
GNU Mono is also a great place to start if you want a free C#/.NET environment. I'm using it to develop in C# on my Powerbook, and it's been smooth sailing so far. I've been impressed with how quickly some of my apps have come together.
.NET is a pretty neat platform, to the extent that it is open and portable. I don't care much for the Windows-specific aspects of it of course.
C# is a nice language. A very refreshing change of pace from C++.
-John
Government subsidies for people to upgrade their TELEVISIONS?
Television is a luxury. There are people in this country who lack basic life necessities.
As soon as it starts costing them money not to. That is the *only* way they will change.
-John
The ID provisions are certainly debatable either way. The disturbing thing is that they never were debated. This was stuck onto an unrelated guaranteed-to-pass bill and came into law despite many people's reservations. This is an extremely sleazy tactic.
-John
I could buy a PSP and a game... or I could spend the same amount on 18 additional games for my Gameboy Advance.
The PSP's screen is beautiful, and the analog controller is most welcome. I played a friend's briefly this morning, and I was very impressed. I held the screen close and felt immersed in the game environment in a way that I haven't ever experienced with a handheld. But I am not at all convinced that, on average, PSP games are more than twice as fun as GBA games (they are twice as expensive).
Portable gaming is different from console or computer gaming. Portable games need to be quick to start and quick to end. Good graphics and music help, but they are not nearly as important to the overall experience as they are on a console. Frogger's Adventures, Advance Wars, and even ports of old NES games such as Zelda and Metroid are excellent handheld games because you can get into them quickly, have fun, and put them down on short notice. The media experience isn't stunning, but it is sufficient, and the gameplay is compelling.
The Gameboy Advance SP is compact, rugged, and relatively cheap ($80). Games are also cheap ($15-20). The batteries last a long time. There is a nice backlight. It fits easily in a pocket and will probably survive the ensuing beating. The system is no longer cutting edge, but I contend that it is still the best all-around handheld gaming system out there, considering price, games, and overall fun.
Minor GBA gripe: why are the power connector and headphone jack on the same plug? You can't use headphones while you're on AC power. And why couldn't they include a normal headphone jack? I had to buy special headphones just for the GBA.
The Nintendo DS is just an atrocity. What were they thinking? Wireless multiplayer is nice, and the dual screens are neat in some cases (Advance Wars comes to mind), but otherwise the DS seems like an awkward frankentoy.
-John
My problem with Apple's DRM has nothing to do with paying for songs. I've bought quite a lot of music from the iTunes Music Store. My problem arises when I want to transfer my music to a new machine and can't play it without first getting permission from Apple, and can't remember my music store password because I haven't bought anything for a while. Or when my hard drive crashes and their DRM measures get in my way when I try to rebuild my music library. (The iTMS doesn't let you re-download music you've already bought.)
But thankfully JHymn and a shareware iPod recovery utility fixed all of that, and my iTunes music is now DRM-free. So if the iTMS ever goes under (less probable things have happened) or something unfavorable happens to Apple, my investment won't be lost.
I will avoid DRM whenever I can. It reduces the value of the product and causes needless frustration.
-John
Alright, so just be sure that the Flash player you develop using this spec also happens to be able to export at least one valid SWF file. Then it's a product that creates SWF, that just happens to also be able to play it.
-John
But if you do ever end up with a case of melanoma, don't throw up your hands and panic. My case is in a partial remission, and there's a good chance it'll stay that way until a complete cure is available. (Which, at the current rate of research, might be sooner rather than later.)
Chemotherapy is very nasty, but it did stop my tumors from growing. I'm currently on a much less nasty maintenance treatment that will hopefully keep them that way. I'll gladly live with daily interleukin-2 shots and a couple of nights on an IV every few months if it means I won't be eaten alive by tumors.
That's my blog, by the way.
-John
Georgia Tech used social security numbers all over the place for a long time, but last year someone rattled the right chains and got the entire system switched over to GTID numbers. It was a huge pain in the ass, but they get props for pulling it off.
It used to be BAD. You could stand by the computer lab printer and collect physics homework printouts with social security numbers in the headers.
Most of these systems were implemented in a time when identity theft was not nearly the high-profile problem it is today. Using SSN's wasn't considered bad. Once a big system like that is in place, it's really hard to change. (I suspect the legal department had something to do with getting Georgia Tech to switch.)
-John