I just read more info about this; this sounds like it provides an escape hatch when the load goes sky high. This is a quote from an Eric Allman interview on sendmail.net:
Are there features in sendmail that people should be aware of but aren't?
Oh, there are probably dozens of them. One that comes to mind, a very simple one, is the fallback MX option, which lets you redirect mail that has failed the first time to another location. It essentially acts as a lowest possible priority MX record for all hosts. For example, if you've got a mail system that's got a lot of traffic going through it, you have another machine that you dedicate to the slow mail, the stuff that didn't go through the first time, where presumably you're less concerned about how quickly it goes because the other end's being slow. So you set your initial connection timeout to something low - five seconds, ten seconds, whatever's right for your site - and you set the fallback MX on your main site to this fallback host. That way the mail that's going to go through quickly just goes fsssssssst right through your main server, while the stuff that's going to be slow (because the other end is either slow to connect or down) goes off to this other machine and doesn't clog up the main machine. It turns out to be just an amazing win. And these days the price of a PC box running FreeBSD or Linux is close enough to zero that it might as well be zero, so it's not really a problem to do it.
Hasn't anyone else wondered if there is a connection between Linus' change of attitude towards minor kernel numbers and his work at Transmeta? Compared to the development time of the 2.1 kernel, the following pace is downright breakneck; 2.1 was released in 1996, but 2.2 and 2.3 were released in 1999, and 2.4 might appear by year's end. Would a port to Crusoe (the Transmeta platform) be justification for kernel release 3.0, despite being one port of several? At this pace, 2.9 is surprisingly close. Forgive me if this seems naive or just dumb. I am not a kernel developer, and I do not work for Transmeta - ha! I wish I did.
Regarding cheap hardware attachments: You might be thinking of Backer from Danmere Electronics. It holds up to 4 gig. I don't have time just now to convert prices to U.S. dollars... Years ago, the Video Backup System for the Amiga did much the same thing. The author wrote up the Reed-Solomon error correction code in the January 1997 issue of Dr. Dobbs' Journal.
I like these concepts, but I would love to write a broader replacement for these that uses generic video capture boards, for example. I'd love to elaborate more, but I have to go back to work now. I might write more when I get home.
I might be replying to a bogus interpretation. I am not an expert, but I have read the Schneier book. PICS is a rating system for web pages, apparently categorized by authors for the use of easily offended people who are afraid of the unmediated internet. Authenticated email has nothing to do with this whatsoever. You can get an page securely and anonymously right now.
Let me know how this sounds. We establish a proxy mesh, so that all unencrypted requests for controversial material hit the originating server from non-sensitive territory. We encrypt the connection from our browser to the proxy for untraceability. SSL improves upon PGP/GPG for this purpose. If you are used to PGP terminology, read 'certificate' as 'public key', and 'certification authority' as 'someone the browser trusts.'
GPG/PGP is not a stream cipher. The proxy couldn't pass any part of the file on until it had received the whole thing. In contrast, a streaming cipher like SSL can work on data - and pass it along - as it flows in.
It is already in browsers. In Netscape 2+ and MSIE 3+, you even can add new Certificate Authorities; having Verisign sign your certificate is not strictly necessary, but still useful.
An implementation (with source) is available both inside and outside the United States. SSLeay is a freely available implementation of SSL.
It can handle other protocols. SSLeay has been used in a secure telnet application. See section 16.2 of the FAQ pointed at above for info; the link may fail due to spaces in the anchor name.
A couple of places are implementing secure proxies to normal sites (that is, encrypted connection from the browser to the proxy) - the forthcoming-source proxy with SSL added on by C. Scott Ananian (based on IANS by Brian Ristuccia) and the as-yet-unimplemented commercial Anonymizer.com service. I don't know about the identification verification systems in the tools I note below, but the Certification Authorities should block man-in-the-middle attacks nicely. Of course, no revokation procedures are in place in SSL, but I'm already up way past my bedtime here.
The Internet Junkbuster Proxy, Muffin and RabbIT are all filtering proxies, well-adapted to block PICS quickly. These could also anonymize well, to avoid signalling the browser locale to the webserver. Squid is adapted for speed and caching, but not-at-all for filtering; I doubt it has any hooks in the code for that.
As soon as I read the complaint about X not recognizing the truer-than-true-color video card, I recognized the whinging. To attempt clarification: I thought that the confusing interface led to the inability to cut-and-paste, or drag-and-drop. I like the middle-button-paste except when I have a two-button mouse.
Bandwidth conservation holds an appeal for me, and along with the cpu time involved in packing and unpacking everything into X drawing instructions, transferring drawing instructions as widgets (gtk, tk, display postscript) sounds like a positive thing. I haven't had a chance to see the shared memory or OpenGL extensions; I heard that extensions have to be compiled in and I postponed it indefinitely.
Hardware acceleration/locality: Playing Quake2 over 10baseT is awkward; that's an area where client/server could definitely use an intelligent terminal, and avoiding streaming over a socket if possible (yes, bypass client/server entirely). It's a bit of an extreme, I know, but video and games should be no challenge whatsoever for Linux and X.
I have been wondering how multimedia (specifically, video) can be added to Linux and X. Streamlining seems necessary to me; a video extension, perhaps? Or a window manager (see NeWS) that handles different protocols? Or would you guess that shared memory can handle these efficiently? I just want to see the multimedia capabilities of Amiga added to Linux, and I'm curious about what is preventing that.
Second, that this topic is growing really quickly and in the time it took to compose this, much of this has become redundant - at least I have a link to another copy of the Unix Haters Handbook, because it just seemed appropriate to mention the canonical criticism site about Unix. This is from the X Windows portion, specifically The X-Windows Disaster; here's a brief summary of highlights.
Confusing user interface/Too much versatility, leading to overly complex or impossible interprogram communication: "cut-and-paste never works properly with X (unless you are cutting and pasting straight ASCII text), drag-and-drop locks up the system, colormaps flash wildly and are never installed at the right time, keyboard focus lags behind the cursor, keys go to the wrong window, and deleting a popup window can quit the whole application".
X is a non-extensible window server - in contrast to NeWS. X was based around the concept of a dumb graphical terminal, and it uses a lot of data to achieve that. In contrast, NeWS and Java offer a somewhat more intelligent terminal interface to the client, and they make better use of less data.
X programs have lots of nasty user interface problems, including X configuration.
(This is about halfway through, then the complaining gets more heated and lengthier, like sitting in a Unix Users Anonymous group and hearing about how someone hit the bottom.)
X has bad hardware support - This is out of place, isn't it?
X isn't device independent, or maybe has a limited graphical toolkit? "Drawing arcs is probably impossible in a portable fashion."
The NeWS link includes a complaint about the constant reinventing of the wheel necessary to deal with the toolkits: if you need to invent a layer of abstraction over and over, why don't you just call that the base toolkit? This makes me wonder if the choice of toolkits is lost upon the author (Barry Shein) or something; you _don't_ send e.g. gtk or tk primitives over the network for display, do you?
Allowing alternate display primitives makes some sense to me; adding, say, an OpenGL extension simply to incorporate double-buffering seems like overkill. But then, how, outside of an extension, can you make use of an accelerated card, without processing the lowest-common-denominator drawing primitives? Using the X protocol, can you exploit accelerated hardware to anti-alias text and graphics, for example?
Other criticism I've heard that the X protocol should take advantage of the locality if the client and server are operating on the same machine. This only makes much sense to me if the cpu overhead in dealing with the network protocol is noticeable; being able to transparently work from another machine is too nifty to throw away.
By a coincidence, I was speaking to a more X-literate friend (hi Eric!) about this last night. My knowledge is badly limited; he had to explain the purpose of the window manager to me. So please, if you want to flame me, be brief.
The plotlines in Cryptonomicon didn't intertwine nearly so much as I would have liked. For the most part they were separate stories; so, the relentless jumping from plotline to plotline was irritating. The scene jump from plane to beach to plane was a hallucination or daydream, and I thought that was pretty obvious. Shaftoe unintentionally responded to Big Lizard stuff near Reagan and The General, so the situation left its mark on him.
The reviewer made some putdown on D.F. Wallace; I thought David Foster Wallace's "Infinite Jest" was well constructed, with the same relentless switching between plotlines. Hey reviewer: did you notice that it's meant to be read in a loop, over and over again? It makes a _lot_ more sense. Different perspectives are brought up, and they add to the earlier parts of the novel.
But then I assume other people notice a large DFW influence on the structure, themes of, and approach to irony of "Cryptonomicon".
Slashdot Mirror
This is a quote from an Eric Allman interview on sendmail.net:
Are there features in sendmail that people should be aware of but aren't?
Oh, there are probably dozens of them. One that comes to mind, a very simple one, is the fallback MX option, which lets you redirect mail that has failed the first time to another location. It essentially acts as a lowest possible priority MX record for all hosts. For example, if you've got a mail system that's got a lot of traffic going through it, you have another machine that you dedicate to the slow mail, the stuff that didn't go through the first time, where presumably you're less concerned about how quickly it goes because the other end's being slow. So you set your initial connection timeout to something low - five seconds, ten seconds, whatever's right for your site - and you set the fallback MX on your main site to this fallback host. That way the mail that's going to go through quickly just goes fsssssssst right through your main server, while the stuff that's going to be slow (because the other end is either slow to connect or down) goes off to this other machine and doesn't clog up the main machine. It turns out to be just an amazing win. And these days the price of a PC box running FreeBSD or Linux is close enough to zero that it might as well be zero, so it's not really a problem to do it.
Hasn't anyone else wondered if there is a connection between Linus' change of attitude towards minor kernel numbers and his work at Transmeta?
Compared to the development time of the 2.1 kernel, the following pace is downright breakneck; 2.1 was released in 1996, but 2.2 and 2.3 were released in 1999, and 2.4 might appear by year's end. Would a port to Crusoe (the Transmeta platform) be justification for kernel release 3.0, despite being one port of several? At this pace, 2.9 is surprisingly close.
Forgive me if this seems naive or just dumb. I am not a kernel developer, and I do not work for Transmeta - ha! I wish I did.
You might be thinking of Backer from Danmere Electronics. It holds up to 4 gig. I don't have time just now to convert prices to U.S. dollars...
Years ago, the Video Backup System for the Amiga did much the same thing. The author wrote up the Reed-Solomon error correction code in the January 1997 issue of Dr. Dobbs' Journal.
I like these concepts, but I would love to write a broader replacement for these that uses generic video capture boards, for example.
I'd love to elaborate more, but I have to go back to work now. I might write more when I get home.
PICS is a rating system for web pages, apparently categorized by authors for the use of easily offended people who are afraid of the unmediated internet. Authenticated email has nothing to do with this whatsoever. You can get an page securely and anonymously right now.
Let me know how this sounds. We establish a proxy mesh, so that all unencrypted requests for controversial material hit the originating server from non-sensitive territory. We encrypt the connection from our browser to the proxy for untraceability.
SSL improves upon PGP/GPG for this purpose. If you are used to PGP terminology, read 'certificate' as 'public key', and 'certification authority' as 'someone the browser trusts.'
- GPG/PGP is not a stream cipher. The proxy couldn't pass any part of the file on until it had received the whole thing. In contrast, a streaming cipher like SSL can work on data - and pass it along - as it flows in.
- It is already in browsers. In Netscape 2+ and MSIE 3+, you even can add new Certificate Authorities; having Verisign sign your certificate is not strictly necessary, but still useful.
- An implementation (with source) is available both inside and outside the United States. SSLeay is a freely available implementation of SSL.
- It can handle other protocols. SSLeay has been used in a secure telnet application. See section 16.2 of the FAQ pointed at above for info; the link may fail due to spaces in the anchor name.
A couple of places are implementing secure proxies to normal sites (that is, encrypted connection from the browser to the proxy) - the forthcoming-source proxy with SSL added on by C. Scott Ananian (based on IANS by Brian Ristuccia) and the as-yet-unimplemented commercial Anonymizer.com service. I don't know about the identification verification systems in the tools I note below, but the Certification Authorities should block man-in-the-middle attacks nicely. Of course, no revokation procedures are in place in SSL, but I'm already up way past my bedtime here.The Internet Junkbuster Proxy, Muffin and RabbIT are all filtering proxies, well-adapted to block PICS quickly. These could also anonymize well, to avoid signalling the browser locale to the webserver. Squid is adapted for speed and caching, but not-at-all for filtering; I doubt it has any hooks in the code for that.
I thought that the confusing interface led to the inability to cut-and-paste, or drag-and-drop. I like the middle-button-paste except when I have a two-button mouse.
Bandwidth conservation holds an appeal for me, and along with the cpu time involved in packing and unpacking everything into X drawing instructions, transferring drawing instructions as widgets (gtk, tk, display postscript) sounds like a positive thing. I haven't had a chance to see the shared memory or OpenGL extensions; I heard that extensions have to be compiled in and I postponed it indefinitely.
Hardware acceleration/locality: Playing Quake2 over 10baseT is awkward; that's an area where client/server could definitely use an intelligent terminal, and avoiding streaming over a socket if possible (yes, bypass client/server entirely). It's a bit of an extreme, I know, but video and games should be no challenge whatsoever for Linux and X.
I have been wondering how multimedia (specifically, video) can be added to Linux and X. Streamlining seems necessary to me; a video extension, perhaps? Or a window manager (see NeWS) that handles different protocols? Or would you guess that shared memory can handle these efficiently? I just want to see the multimedia capabilities of Amiga added to Linux, and I'm curious about what is preventing that.
Second, that this topic is growing really quickly and in the time it took to compose this, much of this has become redundant - at least I have a link to another copy of the Unix Haters Handbook, because it just seemed appropriate to mention the canonical criticism site about Unix. This is from the X Windows portion, specifically The X-Windows Disaster; here's a brief summary of highlights.
- Confusing user interface/Too much versatility, leading to overly complex or impossible interprogram communication: "cut-and-paste never works properly with X (unless you are cutting and pasting straight ASCII text), drag-and-drop locks up the system, colormaps flash wildly and are never installed at the right time, keyboard focus lags behind the cursor, keys go to the wrong window, and deleting a popup window can quit the whole application".
- X is a non-extensible window server - in contrast to NeWS. X was based around the concept of a dumb graphical terminal, and it uses a lot of data to achieve that. In contrast, NeWS and Java offer a somewhat more intelligent terminal interface to the client, and they make better use of less data.
- X programs have lots of nasty user interface problems, including X configuration.
- (This is about halfway through, then the complaining gets more heated and lengthier, like sitting in a Unix Users Anonymous group and hearing about how someone hit the bottom.)
- X has bad hardware support - This is out of place, isn't it?
- X isn't device independent, or maybe has a limited graphical toolkit? "Drawing arcs is probably impossible in a portable fashion."
The NeWS link includes a complaint about the constant reinventing of the wheel necessary to deal with the toolkits: if you need to invent a layer of abstraction over and over, why don't you just call that the base toolkit? This makes me wonder if the choice of toolkits is lost upon the author (Barry Shein) or something; you _don't_ send e.g. gtk or tk primitives over the network for display, do you?Allowing alternate display primitives makes some sense to me; adding, say, an OpenGL extension simply to incorporate double-buffering seems like overkill. But then, how, outside of an extension, can you make use of an accelerated card, without processing the lowest-common-denominator drawing primitives? Using the X protocol, can you exploit accelerated hardware to anti-alias text and graphics, for example?
Other criticism I've heard that the X protocol should take advantage of the locality if the client and server are operating on the same machine. This only makes much sense to me if the cpu overhead in dealing with the network protocol is noticeable; being able to transparently work from another machine is too nifty to throw away.
By a coincidence, I was speaking to a more X-literate friend (hi Eric!) about this last night. My knowledge is badly limited; he had to explain the purpose of the window manager to me. So please, if you want to flame me, be brief.
The reviewer made some putdown on D.F. Wallace; I thought David Foster Wallace's "Infinite Jest" was well constructed, with the same relentless switching between plotlines. Hey reviewer: did you notice that it's meant to be read in a loop, over and over again? It makes a _lot_ more sense. Different perspectives are brought up, and they add to the earlier parts of the novel.
But then I assume other people notice a large DFW influence on the structure, themes of, and approach to irony of "Cryptonomicon".
Chops-Frozen-Water has it right; see www.asciimation.co.nz.
On Yahoo, I found a mirror locator in addition to mirrors at Ohio State, Switzerland, Internet FAQ Consortium, Japan, California, and the United Kingdom. Also noted in the discussion is a Slashdot reader mirror which could get Slashdotted.
A good description of what you need to do was posted on Slashdot a few weeks ago as a story.