Re: [SLUG] where to get an Ethernet hub (NOT a switch)
On Sun, Jul 19, 2009 at 09:36:47AM +1000, Amos Shapira wrote: I'm looking for an Ethernet hub to be used for network troubleshooting (trying to find which of our hosts is involved in the load on our office uplink). I bought a few Dlink 10MB hubs from the US quite some time back for messing with network sniffing. Didn't reply earlier as I couldn't remember where they were, but I've found them tonight. :-) So you're welcome to one if you'd like Amos. Ping me off-list and we'll tee something up. Cheers, Gavin -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
[SLUG] odd system loss
If there are non-professional readers of this list, they might be interested in how this was resolved. (And even professionals *might* be curious as to why and how). 1. I was able to mount another distro from the second disk (so grub was working). (It was suggested that in other circumstances a live OS could be booted. I tried to use supergrub, but possibly hadn ot made the CD bootable?) 2. I made a new directory and mounted the / partition on it. (Accessing /etc meant that I could read fstab). 3. I mounted the other partitions to the directories under / (I realise now that vmlinuz was probably broken linked on / becaause /boot was not mounted. Derr! 4. I chrooted into the new / 5. It seemed to be possible to fix a kernel without destroying everything else. This was my BIG question ... I was even tempted to use the chroot as a sort of virtual machine. But was a little cautious about repeating disaster. In the meantime I had to press on with my tasks using an underpowered and less memory/hard disk machine (though using Ubuntu 8.10) I had no problems with complex convert scripts, with no memory or hard disk problems. So this does not seem to have caused my original failure. 6. There was a suggestion about using apt-get reinstall kernel, but htis seems to be a wish rather than an option. Right? But doing an apt-get update/upgrade got me a new ? security upgrade, which was great. Installing the current kernel did not seem to work, but perhaps it did occur, but grub problem stopped booting) 7. I tried update-grub next. This said it could not find the root, corrupted fstab? trying hda1. Which was no use! 8. fstab was perfectly good. But grub was having trouble. I do not understand this new-fangled UUID or whatever.. so i thought this might be the problem. I removed the UUID and uncommented the /sdb 's 9. BINGO. 10. So did something corrupt the identification of the SATA disks? I thought the point of ther ID was to label the disk unmistakably? 11. Remaining problem. Screen resolution was 600x480. In administration I could make it lower, but not higher. Real mess. 12. I tried nvidia-settings, but that just seemed to tell me that was the best I could do ... but I do not know this program. 13. Debian to the rescue. dpkg-reconfigure xserver-xorg 14. Success. I do not have Compiz eye-candy, I can live without that while I churn out data.. The suggestion about bad reboot seems most plausible--but I still do not know why it would mess up both identification of disks, AND graphics config. I am left with my mistyping of 1680x1260 by 1680/1260. I have recently moved from my home in Surry Hills. But based on that experience, I think Sydney needs a LUG group for amateurs. Newbies are catered for--if they are entering the profession. But there must be other people who are clearly not beginners, but have problems keeping up with technology, for whom the internet is not home territory, have no network, but need computers and are not content with M$. Such people ask questions which appear obvious, or a case of not RTFM. Knowledge of Punched cards do not help with sound cards under ALSA. We cannot expect people whose time is limited, who are under pressure to give professional advice gratis!!! This is unreasonable ... but I am thinking of a local network of shared knowledge from those who use computers but do make a living from them. Or are there too few in Sydney? Googling often shows the problem is known -- but even there the question may hang unanswered! I am well past my biblical use-by date, which does not help in terms of circle of acquaintances, and why I like now to keep up reading the discussions here, though I cannot attend meetings. cheers, Geoffrey -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] where to get an Ethernet hub (NOT a switch)
Hi Gavin, I'm supposed to be busy helping my wife move her pilateststudio this weekend but hope to find time to come over. How much would you like for it? I'm waiting for the hub (hopefully not a switch) to arrive to the office this Monday but if it turns out a dud then I'd like to have something else to try. My mobile is 0416 520 655. Thanks! --Amos 2009/7/24 Gavin Carr ga...@openfusion.com.au: On Sun, Jul 19, 2009 at 09:36:47AM +1000, Amos Shapira wrote: I'm looking for an Ethernet hub to be used for network troubleshooting (trying to find which of our hosts is involved in the load on our office uplink). I bought a few Dlink 10MB hubs from the US quite some time back for messing with network sniffing. Didn't reply earlier as I couldn't remember where they were, but I've found them tonight. :-) So you're welcome to one if you'd like Amos. Ping me off-list and we'll tee something up. Cheers, Gavin -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] odd system loss
2009/7/25 Geoffrey Cowling geoffrey.cowl...@gmail.com: 2. I made a new directory and mounted the / partition on it. (Accessing /etc meant that I could read fstab). 3. I mounted the other partitions to the directories under / (I realise now that vmlinuz was probably broken linked on / becaause /boot was not mounted. Derr! 4. I chrooted into the new / 5. It seemed to be possible to fix a kernel without destroying everything else. This was my BIG question ... I was even tempted to use the chroot as a sort of virtual machine. But was a little cautious about repeating disaster. In the meantime I had to press on with my tasks using an underpowered and less memory/hard disk machine (though using Ubuntu 8.10) I had no problems with complex convert scripts, with no memory or hard disk problems. So this does not seem to have caused my original failure. 6. There was a suggestion about using apt-get reinstall kernel, but htis seems to be a wish rather than an option. Right? But doing an aptitude has a reinstall option, and besides is more powerful. It also has full command line interface like apt-get so no down side for switching to it. apt-get update/upgrade got me a new ? security upgrade, which was great. Installing the current kernel did not seem to work, but perhaps it did occur, but grub problem stopped booting) 7. I tried update-grub next. This said it could not find the root, corrupted fstab? trying hda1. Which was no use! That possibly happened because the chroot'ed environment didn't have access to /dev, /sys and /proc, what you need to do AFTER mounting the root partition and BEFORE the chroot is: # for i in sys proc dev; do mount -o bind /$i /root/$i; done (assuming your going-to-be-chrooted root partition is mounted under /root) I'm not sure this is the reason but it's a good thing to do when dealing with kernel installation inside chroot in any case - mkinitrd needs this for instance if you install new kernel modules. (rest deleted). In all your post I couldn't find the string fsck - have you tried to force-check the suspected partitions? Cheers, --Amos -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] odd system loss
Geoffrey Cowling geoffrey.cowl...@gmail.com writes: [...] 6. There was a suggestion about using apt-get reinstall kernel, but htis seems to be a wish rather than an option. Right? It exists, but was presumably poorly described: apt-get install --reinstall your-package-here [...] 7. I tried update-grub next. This said it could not find the root, corrupted fstab? trying hda1. Which was no use! 8. fstab was perfectly good. But grub was having trouble. I do not understand this new-fangled UUID or whatever.. so i thought this might be the problem. I removed the UUID and uncommented the /sdb 's 9. BINGO. You will want to make sure that 'update-grub' does the right thing when you are booted from the hard disk; it would suck to discover that it restored the broken settings next time the kernel updated... 10. So did something corrupt the identification of the SATA disks? I thought the point of ther ID was to label the disk unmistakably? The UUID is part of the *filesystem*, not the disk; they point is to be able to identify the content without reference to the physical location. Regards, Daniel -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] where to get an Ethernet hub (NOT a switch)
Amos Shapira wrote: On Sun, Jul 19, 2009 at 09:36:47AM +1000, Amos Shapira wrote: I'm looking for an Ethernet hub to be used for network troubleshooting (trying to find which of our hosts is involved in the load on our office uplink) Hi Amos, I might be a little late now... if you've progressed this far with the hub option you might as well go all the way now... However, you are doing this the hard way. You don't need an ethernet hub if you already know where the traffic is going. All you need to do is investigate the traffic on your office uplink. Its possible that the device you use for the uplink already might give you this info... but if it doesn't, you should replace the uplink device with a Linux PC and just sniff the traffic from there. Starting from scratch this should take about 2 hours to complete (assuming it takes an hour to install your favourite flavour of Linux and you're not using mesh VPNs or other complex configurations). Ideally you would configure the Linux PC to be the local gateway, and then reconfigure the existing uplink device to provide the link between the Linux PC and outside. If you want to really get your hands dirty, you could configure the Linux box with 2 interfaces as a bridge and simply insert it in between your switch and your office uplink. This would allow you to sniff the traffic without needing to change any IP configs on the existing network. (Ah, I see Rob Collins said something like this last week - you can make a trivial two port switch out of a linux machine with brtools). Cheers, Marty -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] where to get an Ethernet hub (NOT a switch)
2009/7/25 Marty Richards ma...@netwaynetworks.com.au: However, you are doing this the hard way. You don't need an ethernet hub if you already know where the traffic is going. All you need to do is investigate the traffic on your office uplink. Its possible that the device you use for the uplink already might give you this info... but if it We use SonicWall TZ 190. It gives very rought traffic per IP in is Logs screen but to get all the details we'll need to purchase something called SonicView and run it on Windows. doesn't, you should replace the uplink device with a Linux PC and just sniff the traffic from there. Starting from scratch this should take about 2 hours to complete (assuming it takes an hour to install your favourite flavour of Linux and you're not using mesh VPNs or other complex configurations). Ideally you would configure the Linux PC to be the local gateway, and then reconfigure the existing uplink device to provide the link between the Linux PC and outside. If you want to really get your hands dirty, you could configure the Linux box with 2 interfaces as a bridge and simply insert it in between your switch and your office uplink. This would allow you to sniff the traffic without needing to change any IP configs on the existing network. (Ah, I see Rob Collins said something like this last week - you can make a trivial two port switch out of a linux machine with brtools). That's exactly what we did - put a linux box with two network cards as a bridge between the SonicWall and the SHDSL modem and run ntop on it. It caused troubles due to hardware issues (network card) and later because the linux box had iptables filtering packets. They were resolved and that's how our network is served now but I feel that having our entire uplink depend on a desktop-level linux box I'm not sure its age a bit worrying. I think I'll feel more comfortable if I could let the uplink through a piece of hardware with no moving parts in it if you know what I mean, plus it's something we'll be able to slug around the network more easily, connect my laptop to it and have a listen. Thanks, --Amos -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
