gmane.org.user-groups.linux.gnhlug

Non-GNHLUG events around the area

Ted Roche — 2008-09-06T18:25:12

The Greater Boston Chapter of the Association of Computing Machinery (GBC/ACM) has a meeting upcoming that might be of interest to members: Joint meeting of GBC/ACM and Boston Chapter of IEEE Computer Society Thursday, September 18, 2008, 7-9 pm Broad Institute Auditorium (MIT Building NE30) Main St (between Vassar and Ames Sts), Cambridge, MA Evolvability and Robust Design ** Presented by Gerald Jay Sussman Panasonic Professor of Electrical Engineering at the Massachusetts Institute of Technology Details: http://www.gbcacm.org/seminars/evening/2008/07/evolvability-and-robust-design.html Also note their October meeting is "Security in Voting Systems" by Professor Ronald L. Rivest, MIT CSAIL (the "R" in "RSA") and in November "Open-architectures for Reading, Writing & Computing with Genomes" by George Church. Details can be found off the main http://www.gbcacm.org page. --- The Software Association of New Hampshire (www.swanh.org) will hold its annual all-day InfoXchange conference on Octobe

Re: Linux network behavior wierdness

Dave Johnson — 2008-09-06T00:39:10

Ping can still send, just farm-519's kernel won't reply. I'd assume 10.95.34.112 is some other host on the network that does reply right?

Re: Linux network behavior wierdness

Kevin D. Clark — 2008-09-05T21:39:43

Darrell Michaud writes: I second this recommendation. If there is any network gear in this setup that is filtering out directed broadcasts, this might explain some of the strangeness. Regards, --kevin

Re: Lan + DMZ + LargeNumOfFiles = headaches AKA: plz halp and donateur brain!!

Ted Roche — 2008-09-05T21:19:00

Cool! Have you got an RSS feed for your podcast yet? Then we can subscribe!

Re: Lan + DMZ + LargeNumOfFiles = headaches AKA: plz halp and donateur brain!!

Bill McGonigle — 2008-09-05T19:26:26

I'd reflexively reach for rsync as well, but GlusterFS may do some of what you need automagically: http://www.gluster.org/docs/index.php/ Install_and_run_GlusterFS_v1.3_in_10mins Bill Stearns covered it briefly at DLSLUG a few months back: http://dlslug.org/downloads/podcast/dlslug_200806_stearns_fuse.mp3 -Bill ----- Bill McGonigle, Owner Work: 603.448.4440 BFC Computing, LLC Home: 603.448.1668 bill-6ft+4TUC7y9qCwUM1VThig< at >public.gmane.orgCell: 603.252.2606 http://www.bfccomputing.com/ Page: 603.442.1833 Blog: http://blog.bfccomputing.com/ VCard: http://bfccomputing.com/vcard/bill.vcf

Re: Linux network behavior wierdness

Neil Joseph Schelly — 2008-09-05T18:48:21

ping -b "farm-519's broadcast" ...ought to have no response from farm-519. It won't respond to them, but it can still send broadcast pings. -N

Re: Linux network behavior wierdness

Paul Lussier — 2008-09-05T18:26:45

Fascinating, so how does this work? $ ssh farm-519 ping -b 10.95.255.255 -c 1 64 bytes from 10.95.34.112: icmp_seq=1 ttl=64 time=0.074 ms 1 packets transmitted, 1 received, 0% packet loss, time 0ms $ ssh farm-519 cat /proc/sys/net/ipv4/icmp_echo_ignore_broadcasts 1

Re: Lan + DMZ + LargeNumOfFiles = headaches AKA: plz halp and donate ur brain!!

Darrell Michaud — 2008-09-05T17:53:24

Using rsync or unisom or any of the improvements on top of rsync as a direct replacement for FTP would be a low-hanging fruit improvement. Tunneling it over an encrypted layer such as SSH improves security as well. You're absolutely right that if you have a cluster of machines in the DMZ, a more scalable architecture is to have them all share storage rather than unicast-replicate to each webserver individually. So you have to choice between SAN / NAS to do this. NAS is generally cheaper for a mature solution on a budget. Perhaps your next lowest hanging fruit is to put a secure NAS on your DMZ, then replicate to it from your internal trusted network via a single port. Rsync / unisom again, over an encrypted protocol like SSH. There are many possible variations - using stronger or weaker security on the replication channel depending on the exact use case and data, replicating on an event-driven system instead of via polling, buying the replication software or NAS appliance(s) that handles replication alre

Re: Lan + DMZ + LargeNumOfFiles = headaches AKA: plz halp and donateur brain!!

Andy Bair — 2008-09-05T17:30:42

_______________________________________________ gnhlug-discuss mailing list gnhlug-discuss-Z8c80N6yweDq5qozqU1N3A< at >public.gmane.org http://mail.gnhlug.org/mailman/listinfo/gnhlug-discuss/

Re: Linux network behavior wierdness

Paul Lussier — 2008-09-05T16:42:14

Definitely not. I've found that just running Linux "can lead to weird behaviors like what you describe." :-/

Re: Linux network behavior wierdness

Paul Lussier — 2008-09-05T16:39:14

It's a /16 network. 10.95.255.255 exhibits identical behavior fwiw. Ooh, I didn't know that, thanks!

RE: Phones for Asterisk and single-pair old phone wiring?

Michael Pelletier — 2008-09-05T16:08:23

I was thinking it would be easy enough to adapt a wall wart to power the unit at the desks - here's a 24V 750mA unit for $13.50 each: http://www.powerstream.com/24-volt-dir.htm The DDW-220 pulls 300mA at 20VDC. Either attach a socket (Radio Shack) to the power lead or hard-wire the wall wart. Or perhaps you could run power over another pair of the old copper, if available, to power multiple units from a larger DC power supply in the datacenter. Ah, the joys of legacy hardware... -Michael Pelletier. -----Original Message----- From: gnhlug-discuss-bounces-Z8c80N6yweDq5qozqU1N3A< at >public.gmane.org [mailto:gnhlug-discuss-bounces-Z8c80N6yweDq5qozqU1N3A< at >public.gmane.org] On Behalf Of Ben Scott Sent: Thursday, September 04, 2008 7:32 PM To: gnhlug-discuss-Z8c80N6yweDq5qozqU1N3A< at >public.gmane.org Subject: Re: Phones for Asterisk and single-pair old phone wiring? On Thu, Sep 4, 2008 at 9:43 AM, Michael Pelletier public.gmane.org> wrote: That's what I said. Only more colorful.

Re: Lan + DMZ + LargeNumOfFiles = headaches AKA: plz halp and donateur brain!!

Ben Scott — 2008-09-05T15:31:12

If practical, you may want to experiment with scripting something that runs on the source host to archive the many small files into one big file, transfers the one big file, then runs on the target host to unpack the archive. (Operations on one big file are generally much faster than many smaller ones. It's sometimes better to take that hit twice locally (once on each host), rather than once on the network. (Local disk and filesystem being faster than network.)) I'll second Andy's suggestion of rsync, which is much better at this kind of thing. You could even combine it with the one-big-archive-file idea. Use rsync to replicate a directory with the file(s) to the other hosts, and have the other host(s) monitor that directory for files to unpack. Just a Small Matter of Programming. ;-) I'd recommend against that king of thing. Neither NFS nor CIFS are "firewall friendly", so if you have a DMZ, you'll want to avoid trying to have them cross the firewall. (There are things that can be done

Re: Linux network behavior wierdness

Ben Scott — 2008-09-05T15:22:07

In addition to the other (probably better) things people have suggested, are any of these hosts running an iptables firewall with connection tracking? State table overflow can lead to weird behaviors like what you describe.

RE: Linux network behavior wierdness

Darrell Michaud — 2008-09-05T14:53:07

There also might be a tiny possibility that the infrastructure switches are filtering or otherwise interfering with the broadcast ping. It might we worth testing with with a single dumb switch, or even a crossover cable.

RE: Linux network behavior wierdness

Michael Pelletier — 2008-09-05T14:38:41

The all-zeroes broadcast address was de rigeur for SunOS 4.x systems, and systems of later vintage than that typically used all-ones. As I recall, many modern systems won't recognize all-zero as a broadcast address unless they're instructed to. This may explain the different outcomes on different systems. I'd also suggest you double-check your netmasks - a packet to 192.168.128.255 won't be responded to unless the receiving system's netmask is such that the left half of the origin address matches its idea of the network, and the right half is all-1. -Michael Pelletier. -----Original Message----- From: gnhlug-discuss-bounces-Z8c80N6yweDq5qozqU1N3A< at >public.gmane.org [mailto:gnhlug-discuss-bounces-Z8c80N6yweDq5qozqU1N3A< at >public.gmane.org] On Behalf Of Paul Lussier Sent: Friday, September 05, 2008 10:04 AM To: gnhlug-discuss-Z8c80N6yweDq5qozqU1N3A< at >public.gmane.org Subject: Linux network behavior wierdness Hi all, I have a wierd problem where some hosts respond to a broadcast ping packet and others don't.

Re: Linux network behavior wierdness

Dave Johnson — 2008-09-05T14:27:50

10.95.0.0 is an unusual broadcast address, how did you end up with that? Watch out for /proc/sys/net/ipv4/icmp_echo_ignore_broadcasts. The default was changed between 2.6.13 and 2.6.14 to ignore by default.

[GNHLUG] SLUG / Mon 8 Sep / HTTP for Fun and Profit

Robert E. Anderson — 2008-09-05T14:07:40

Who : Brian Turnbull What : HTTP for Fun and Profit Date : Mon 8 Sep 2008 Time : 7 PM to 9 PM Where: UNH Durham, Morse Hall room 332 Peek under the hood of the HyperText Transfer Protocol. ------------------------------------------------------- The HyperText Transfer Protocol (HTTP) powers the World Wide Web. Every web page requested and displayed in a web browser is delivered via HTTP. But HTTP can facilitate all sorts of client/server communication. In this talk, Brian Turnbull will discuss and present the major aspects of the protocol for application to your own projects. Next month, Brian will present the second part of the presentation, "RESTful Web Services". REpresentational State Transfer is the theoretical underpinnings of HTTP/1.1. This talk will explain what REST is, present examples of existing web services using REST, and also covers the practical application of REST and the Atom Publishing Protocol in creating a web service. For directions to this talk and/or more information ab

Linux network behavior wierdness

Paul Lussier — 2008-09-05T14:04:18

Hi all, I have a wierd problem where some hosts respond to a broadcast ping packet and others don't. I have some hosts which, when I do a ping -b 10.95.0.0 everything answers. On other hosts, doing exactly the same thing, I get no response. A reboot resets a "broken" host, but over time it will re-develop the problem. And I can't seem to figure out how to make the problem occur... I can't figure out if it's something we're doing which is causing this change, or if it's a kernel thing where some threshold is reached and it just stops. Fwiw, we're running Debian/Etch with a 2.6.18 kernel. Most NICs are Intel e1000, though some are broadcom. In general, I've seen it happen across our lab on different hardware platforms with different motherboards and nics. Any insights would be most appreciated.

Re: Lan + DMZ + LargeNumOfFiles = headaches AKA: plz halp and donateur brain!!

Andy Bair — 2008-09-05T00:17:02

_______________________________________________ gnhlug-discuss mailing list gnhlug-discuss-Z8c80N6yweDq5qozqU1N3A< at >public.gmane.org http://mail.gnhlug.org/mailman/listinfo/gnhlug-discuss/

Re: Phones for Asterisk and single-pair old phone wiring?

Ben Scott — 2008-09-04T23:32:08

That's what I said. Only more colorful. ;-) I saw it, and even saved note of it. It's rather more of an industrial design that is suitable (DIN rail mount, needs DC wired-in power supply), but might be adaptable for our purposes. I having a feeling it's not appropriate for this project, but it may come in useful for others. :)