"The Linux Gazette...making Linux just a little more fun!"

(?) The Answer Guy (!)


By James T. Dennis, answerguy@ssc.com
Starshine Technical Services, http://www.starshine.org/

(?) Proxying over PPP

From prashant on Thu, 11 Feb 1999

(?) Hi Answerguy,

I am using Red Hat Linux.And I want to install a proxy server. I have a modem can configure ppp over that.

But i want that proxy to do the following functions:

  1. It should optimize my ppp connection. (webproxy-1.3 does provides this)
  2. As this webproxy doesn't handle cache.A cache manager 'Squid' must be installed.
  3. Also it doesn't supports many protocols. So I want a router linked it

I dont know how i am going to do this please help me.

yours
Prashant Deshpande.

(!) Your list mixes needs with conclusions. I don't recommend that when doing "requirements analysis" as you'll probably end up with some inappropriate constraints.
If I understand it correctly you want to "optimize" your PPP connection in the sense that you want to minimize the traffic flowing over it, and the latency between requests and responses.
I'm not familiar with a package named "webproxy-1.3" --- but any caching/proxy will tend to lessen the traffic depending on your usage patterns and the co-operation of the sites that you access over these protocols. Squid is probably the most advanced caching proxying available --- and it's designed to peer with other ICP (Internet Caching Protocol) servers, (potentially minimizing traffic over other links, further out on the Internet, beyond your PPP link while also minimizing latency).
I don't understand item three at all. What doesn't support many protcocols? Squid supports a number of protocols (all those that are amenable to caching, that I can think of). Also the conclusion: "So I want a router linked it" is completely bogus. A router does routing, a proxy does proxying and caching. These functions operate at different (though sometimes blurred) levels in the OSI reference model.
If you use your Linux system as a "gateway" to the Internet for any systems other than itself (if it has an ethernet and a PPP link or any other combination of two or more non-loopback interfaces) than it probably is acting as a router.
So, let's step back from the constraints implied by these extraneous comments and focus on what you want.
You could do some protocol analysis on your PPP link to determine what protocols are consuming which percentages of the bandwidth; and to determine the average latency among various protocols. This would help you focus on which protocols are likely to benefit the most from caching. It's also possible you might find other ways to help improve your utilization.
Without going into gory details of using 'tcpdump' and performing data analysis on that we can suggest that you start with the basics.
Run a caching nameserver on your PPP/router. This should immediately improve response time and reduce bandwidth utilization by obviating the need to forward/route DNS queries across the link. Make sure to configure the /etc/resolv.conf (or its equivalent on your non-Unix systems) to actually use your caching nameserver. That includes the resolv.conf on the router/gateway itself!
Install Squid and configure your web browsers and any gopher, WAIS, or other supported clients to use it. That should help with those web sites that don't egregiously prevent caching. Note that some sites use HTTP headers (Pragmas) to eliminate or minimize caching of their pages. This is often done by "advertising" supported sites as part of their "imprint" accounting and to support their high traffic claims (to their customers). That is BAD for the Internet as a whole (since it forces every link between those sites and all of their clients to carry redundant traffic). Oh well! There goes the neighborhood!
After you've taken these two steps (and provided your caching proxy/router with LOTS of disk space and memory) you should monitor the line performance (informally) to see if that meets your needs. You've probably gained 80-90% of the potential efficiency gains already --- so additional work will have diminishing returns.
You can install DeleGate for FTP proxying (I don't know how to make "normal" FTP clients talk to Squid's FTP proxying --- but they can be configured to use DeleGate as you'd use any SOCKS proxy, and you can "manually" traver000002104006773443066016202 0ustar rootroot The Answer Guy 38: More Bad Clusters

"The Linux Gazette...making Linux just a little more fun!"

(?) The Answer Guy (!)


By James T. Dennis, answerguy@ssc.com
Starshine Technical Services, http://www.starshine.org/

(?) More Bad Clusters

From Rik on Fri, 05 Feb 1999

(?) Hi,

Do you know how to fix a bad cluster on my hard disk cause I have one and now I can't convert it to FAT32. I've got a Fujitsu U-DMA 1,7 GB HD I hope you can help me.

Thanks in advance Greetingz

(!) Is this some kind of joke? I keep getting questions about fixing bad clusters, marking them as bad, unmarking them from being bad and the like. Worse, these questions seem to come from MS Windows users who seem to have no interest in LINUX whatsoever.
No! I don't know how to force your machine to let you install a FAT32 filesystem on it. I don't care how that's done --- I use ext2 filesystems and they can tolerate and manage bad sectors (or ignore them at your peril) with no problem (just remember to use the -c parameters to mke2fs and e2fsck).
Please, go find a Windows Answer Guy. If you just sent me blind e-mail and don't understand why I'm babbling about this non-MS stuff go read some back issues of the Linux Gazette: http://www.linuxgazette.com
(as you should see in my .sig)

(?) how to fix a bad cluster on hd

From Rik on Sun, 07 Feb 1999

Hi,

I'm sorry but I looked at altavista for bad clusters on how to fix them and there was this message board with your e-mail adress. so that's why I sended my message to you. sorry it would not happen again.

Greetingz

(!) I don't object to getting question (on the topics that are relevant to Linux Gazette). However, it is irritating when those people who find my messages in Alta Vista don't read what I said.
I've never said that I could "fix bad clusters" --- so anything you read that was by me didn't say that. Indeed it almost certainly said almost exactly the same thing I told you.
Noting that this Alta Vista record made reference to linuxgazette.com you have to follow up and look at the "Linux Gazette's" web pages (where you'll find it's own search feature --- which should should have made it obvious who I am and what I do).
I use Yahoo! and Alta Vista (and Deja News and Google and others) extensively. I occasionally even send messages to people who I find therein. However, I do that as a last resort.
Also when contacting someone for the first time, courtesy demands that you introduce yourself. Nothing elaborate but something like:
Answer Guy,
I was searching Alta Vista looking for ways to solve the problems I'm having with bad blocks and Windows '98 on my new/old/whatever hard drive.
I found the following message from you:
...[SHORT quote/excerpt]...
... and then you can go on to ask your question.
That's only common courtesy --- which is unfortunately all too uncommon these days.
So, if you ever have questions about Linux --- including questions about how to make it work with NT, '9x, MacOS, or other systems, feel free to send them to me. Please search through the appropriate newsgroups, mailing lists HOWTOs, FAQs, and try the search feature on http://www.linuxgazette.com to see if I've answered this question before (or especially if any of our other contributors have written feature articles or 2-cent tips or other material on the subject).
For problems with a piece of equipment --- talk to your retailer or its manufacturer first. For problems which don't relate to Linux --- look for forums that focus on the one at hand. When dealing with Microsoft products remember the level of support you've been getting before purchasing any more of them.

Copyright © 1999, James T. Dennis
Published in The Linux Gazette Issue 38 March 1999

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