- WLUG - wlug.mailman3.com

Re: [Wlug] getting that cpu to sleep ...

by Bradley Noyes

On Mon, Dec 12, 2005 at 06:17:35PM -0500, Jeff Moyer wrote: > ==> Regarding [Wlug] getting that cpu to sleep ...; brad <maitre(a)ccs.neu.edu> adds: > > maitre> greetings, > > maitre> I have a question for those linux programmers out there. i'm > maitre> writing a program on linux (kubuntu to be specific) that requires > maitre> high-precision timing, somewhere on the order of 100 to 1000 micro > maitre> seconds. I get very good timing out of a loop written such that a > maitre> while() loop checks the system clock after every iteration and > maitre> comparing that to the desired wait time, like so (pseudo_code): > maitre> while(time_passed < wait_time) { time_passed = get_time() } ... > > maitre> The problem with this approach is that the process uses 99% of the > maitre> CPU since it just spins the CPU until enough time has expired. My > > The other problem with this is that you can be scheduled if your timeslice > runs out. > umm, i didn't think about that one. > maitre> question: is there a way on linux (in C) to have the CPU sleep or > maitre> send it a no-op such that it's not just eating up cycles until time > maitre> expires? I have looked at nanosleep and usleep, however they appear > maitre> to only have precision to 10ms which too latent for my needs. > > As Mike pointed out, in more recent kernels you can tune the value of HZ to > get better granularity from select/poll. > Actually Mike's response reminded me of an article i bumped into about nanosleep on dragonflyBSD http://www.dragonflybsd.org/docs/nanosleep/ > What, precisely, are you trying to do and on what kernel? Perhaps with > more information we could provide better guidance. > The immediate task at hand is that i want to get readings from an instrument (a light sensor) at a uniform interval, say every 1000 micro seconds. I have been able to achieve this task by setting up the loop i described above. However the loop above takes 99% of the CPU. I'd like to be able to achieve this without pegging the CPU at 99%. Does this make sense? if not i can try explaining it again, perhaps with some code. The kernel i'm running is 2.6.12. (well uname -r reports '2.6.12-9-686-smp.' its ubuntu's stock smp kernel.) -brad

Dec. 13, 2005

Re: [Wlug] getting that cpu to sleep ...

by Jeff Moyer

==> Regarding [Wlug] getting that cpu to sleep ...; brad <maitre(a)ccs.neu.edu> adds: maitre> greetings, maitre> I have a question for those linux programmers out there. i'm maitre> writing a program on linux (kubuntu to be specific) that requires maitre> high-precision timing, somewhere on the order of 100 to 1000 micro maitre> seconds. I get very good timing out of a loop written such that a maitre> while() loop checks the system clock after every iteration and maitre> comparing that to the desired wait time, like so (pseudo_code): maitre> while(time_passed < wait_time) { time_passed = get_time() } ... maitre> The problem with this approach is that the process uses 99% of the maitre> CPU since it just spins the CPU until enough time has expired. My The other problem with this is that you can be scheduled if your timeslice runs out. maitre> question: is there a way on linux (in C) to have the CPU sleep or maitre> send it a no-op such that it's not just eating up cycles until time maitre> expires? I have looked at nanosleep and usleep, however they appear maitre> to only have precision to 10ms which too latent for my needs. As Mike pointed out, in more recent kernels you can tune the value of HZ to get better granularity from select/poll. What, precisely, are you trying to do and on what kernel? Perhaps with more information we could provide better guidance. -Jeff

Dec. 12, 2005

Re: [Wlug] getting that cpu to sleep ...

by Mike Frysinger

On Mon, Dec 12, 2005 at 05:48:24PM -0500, brad wrote: > My question: is here a way on linux (in C) to have the CPU sleep or > send it a no-op such that it's not just eating up cycles until time > expires? I have looked at nanosleep and usleep, however they appear > to only have precision to 10ms which too latent for my needs. you cant unless you tweak the kernel HZ settings read this page: http://kerneltrap.org/node/464 -mike

Dec. 12, 2005

getting that cpu to sleep ...

by brad

greetings, I have a question for those linux programmers out there. i'm writing a program on linux (kubuntu to be specific) that requires high-precision timing, somewhere on the order of 100 to 1000 micro seconds. I get very good timing out of a loop written such that a while() loop checks the system clock after every iteration and comparing that to the desired wait time, like so (pseudo_code): while(time_passed < wait_time) { time_passed = get_time() } ... The problem with this approach is that the process uses 99% of the CPU since it just spins the CPU until enough time has expired. My question: is there a way on linux (in C) to have the CPU sleep or send it a no-op such that it's not just eating up cycles until time expires? I have looked at nanosleep and usleep, however they appear to only have precision to 10ms which too latent for my needs. Thanks, --Brad

Dec. 12, 2005

Success, almost, with GNOME

by Ken Jones

Per the suggestion of Chuck Anderson I logged in under a new account. GNOME desktop worked just as it should. So I removed all of the /home/kjones/.gconf directory and logged in again as myself. Still it did not work correctly. In particular the right click on empty space did not work. I did a "diff -r" on the two (now default versions I suppose) .gconf directories. They seemed the same save for unique identifiers. Where do I look to find the differences? One other question. The Applications launcher on GNOME does not contain the LOG OUT feature. I know the command "shutdown", but I can not find a command to Log Out. Is there one? What is it? Ken Jones

Dec. 12, 2005

Re: [Wlug] Problem with gnome, Fedora core 3

by Chuck Anderson

On Sat, Dec 10, 2005 at 03:58:05PM -0500, Ken Jones wrote: > Any ideas what controls this behavior and ow I can fix it? On a > different machine I have a Core4 system running GNOME perfectly. Try creating a new account and logging in to that one to see if the problem exists there. If not, then it is definately something in your user account, such as your gconf settings.

Dec. 10, 2005

Problem with gnome, Fedora core 3

by Ken Jones

Gentlemen and ladies, My Fedora Core 3 - which has been yum'd up to date - behaves strangely when using GNOME as the windows manager. The right click on blank desktop space does not work. The right click on a panel to make a new panel does not work. The result is that I can not set up any launching icons on my desktop. There is no unused space on my one (bottom) panel. The panel-disappear icon is missing. Any ideas what controls this behavior and ow I can fix it? On a different machine I have a Core4 system running GNOME perfectly. Ken Jones

Dec. 10, 2005

Wanted: used laptop power supply

by Andy Stewart

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 HI gang, I'm looking for a used (functioning) laptop power supply. I won't be using it for a laptop. Input: 120VAC 60Hz (standard wall socket) Output: anywhere from 12 VDC - 48 VDC at about 2 amps I need about 24 watts, so the current goes up as V goes down 48 VDC @ 0.5 A, 24 VDC @ 1.0 A, 12 VDC @ 2.0 A, etc the barrel connector will look like this neg ---C. ---pos that pic won't look right, but it is neg on outside pos on the inside Please send email if you have one, and we can negotiate a price, trade, or whatever you'd like. Ideally, you could bring it to the upcoming WLUG meeting on Wednesday, Dec 14th. Thanks! Andy - -- Andy Stewart, Founder Worcester Linux Users' Group Worcester, MA, USA http://www.wlug.org -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.5 (GNU/Linux) Comment: Using GnuPG with Thunderbird - http://enigmail.mozdev.org iD8DBQFDmm/vHl0iXDssISsRAkEPAJ9FapCV+aOZmtS1wUT2VJ4/C14fCQCeI//x 9H6CbNJklxMzQbepGvSBpa0= =1Gi+ -----END PGP SIGNATURE-----

Dec. 10, 2005

Re: [Wlug] Grub problems after imaging drive

by Brett Russ

On 12/7/05, Dick Goodman <wlug(a)goodman1.net> wrote: > root (hd0,0) > setup (hd0) > quit > > The messages after setup did not look like error messages. The behavior is I need to see those messages. > How do I resolve this? What additional information do you need? The messages above and the output of the grub "geometry (hd0)" command, assuming everything is on the first HDD in the system. Also let us know the intended mount point for each of those partitions. Andy is correct in that the best way to figure this out is to work with the grub command line and walk through the steps it would take trying to boot your system. And Eric is correct in that the grub config file would also be handy. Since the disks are partitioned the same my guess is that the problem lies in the grub stage image installation. I believe some filesystems can get away without a stage1_5 (ext2 being one example, likely used on your RH box) and since you didn't supply an explicit image device to the setup command it's possible that the install wasn't able to find them on the root (hd0,0) that you specified. > Is there a better way to clone Linux drive -> Linux drive? Yes, boot from a Linux CD (like the knoppix that you mentioned) and `dd if=/dev/<good> of=/dev/<blank>` <good> might be hda for example. Obviously blank needs to be as big or bigger than good or you risk an incomplete copy and therefore chopped filesystems. BR

Dec. 9, 2005

Re: [Wlug] Grub problems after imaging drive

by Eric Martin

dick, can you post you /boot/grub/grub.conf (or /boot/grub/menu.lst). menu.lst is the old way, it's probably a symlink now... On 12/7/05, Andy Stewart <andystewart(a)comcast.net> wrote: > > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > Dick Goodman wrote: > > I recently configured a RedHat 9 system with OpenVPN . The original > > configuration was done on an old junk box. This is a single boot w/grub > > system > > > > As of last week I knew nothing about grub; I now know marginally more. > > > > As it was working successfully, it was decided to build a new box for > it. > > The hard drive was imaged with Ghost Corporate 8.x and restored onto the > > new drive. There are some known issues with 8.x and grub > > > > The grub screen comes up on booting the new box, but when selecting the > > (one) entry for RH9, after a short pause it comes back to the grub > > screen. I read the grub manual, and from the grub screen did c-command, > > then > > > > root (hd0,0) > > setup (hd0) > > quit > > > > The messages after setup did not look like error messages. The behavior > > is the same, although I see a message about stage 1.5 flicker by. > > I figured out how to look at the hard drive with Knoppix 3.8.2 Live CD > > and the partitions and contents look "ok", so it appears to just be a > > boot issue. > > > > How do I resolve this? What additional information do you need? Is there > > a better way to clone Linux drive -> Linux drive? > > > > Dick > > _______________________________________________ > > Wlug mailing list > > Wlug(a)mail.wlug.org > > http://mail.wlug.org/mailman/listinfo/wlug > > > > Here's what I use for boot commands in GRUB on my system. Its SuSE, but > I don't think it should make a difference. > > root (hd0,0)/vmlinuz <boot parameters> > initrd (hd0,0)/initrd > > - From a GRUB command line, make sure (by using the TAB key) that (hd0,0) > is a legitimate partition, and that it can find /vmlinuz (or whatever > kernel image you are using). If you need initrd, you can use the same > trick with the TAB key to get a poor man's directory listing. > > After you enter those lines, or edit the existing lines to make them > look as above, boot it and you should at least get the kernel to start. > You may need to specify "root=/dev/xxx" as one of the boot parameters > on the "root" command. If you get a panic when it tries to mount root, > it is either because you didn't specify "root=/dev/xxx", or because the > code for the root device isn't present in the kernel (for example, a > SCSI driver or a reiserfs module, as appropriate). I hope root isn't > part of LVM...that's a can of worms you should avoid, but I digress. > > I hope this helps, > > Andy > > - -- > Andy Stewart, Founder > Worcester Linux Users' Group > Worcester, MA, USA > http://www.wlug.org > > -----BEGIN PGP SIGNATURE----- > Version: GnuPG v1.2.5 (GNU/Linux) > Comment: Using GnuPG with Thunderbird - http://enigmail.mozdev.org > > iD8DBQFDlnkCHl0iXDssISsRAuiaAJ0ZhX3Il4sFM2Yt2cCG1IQBZMy11wCfZIcn > bPoThROtkjrTtXGgaHq2Vms= > =J3lU > -----END PGP SIGNATURE----- > _______________________________________________ > Wlug mailing list > Wlug(a)mail.wlug.org > http://mail.wlug.org/mailman/listinfo/wlug >

Dec. 8, 2005

Re: [Wlug] ftp in bash script

by John Stoffel

Gregory> I'm writing a bash script to download a logfile from a site, Gregory> archive it, then upload the archive to the site. I want the Gregory> script to stop if the file doesn't download correctly, and I Gregory> think I've accomplished this. (i.e. it works right when I set Gregory> it up to download a non-existent file.) Can't you run a script on the remote site? That would make the problem trivial. Also, you might want to check and see if your site (if you don't have full control) offers the ability to automatically rotate logs for you, which would make things much simpler all around. Gregory> Question: will ftp always return an error if the file is Gregory> downloaded incorrectly or incompletely? Nope, I don't think it will. You might try to use wget instead. Also, I'd try to download the file, then re-download it and see if the files are the same. If not, then you have a problem. It's a question of whether you're willing to lose logging information from your ftpd server. If you can lose some data. then what you're proposing should work. Gregory> This is important, because the last part of the script will Gregory> replace the file on the ftp server with a blank file of the Gregory> same name. I don't want to wipe out the original logfile if I Gregory> don't have it all. It's hard to do this, because in the time between you download the file, it might log a download (such as the FTP getting the log file itself!) and you'll miss details. Again, look for a solution where you can get the remote site to do the log rotation for you, since with the help of the ftp server, you can make sure you get a clean and consistent log file. Gregory> (secondary question: Is there a way to pass the "delete" Gregory> argument without using the interactive shell?) Not sure. You shouldn't have to anyway, just upload a zero length file over the log file and you'r eall set. Gregory> Here's what the first section of the script looks like. Third Gregory> question: If I set this up to run as a cron job, what happens Gregory> to my echo messages? Will they appear in /var/log/messages? You should look into using 'expect' to do all this work for you, it's the tool to use to automate a manual process. John

Dec. 7, 2005

ftp in bash script

by Gregory Avedissian

I'm writing a bash script to download a logfile from a site, archive it, then upload the archive to the site. I want the script to stop if the file doesn't download correctly, and I think I've accomplished this. (i.e. it works right when I set it up to download a non-existent file.) Question: will ftp always return an error if the file is downloaded incorrectly or incompletely? This is important, because the last part of the script will replace the file on the ftp server with a blank file of the same name. I don't want to wipe out the original logfile if I don't have it all. (secondary question: Is there a way to pass the "delete" argument without using the interactive shell?) Here's what the first section of the script looks like. Third question: If I set this up to run as a cron job, what happens to my echo messages? Will they appear in /var/log/messages? #download logfile if ftp ftp://user:password@ftp.site.net/logfile.log; then echo echo "File has been downloaded" echo else echo "Download failed" exit fi Thanks, Greg

Dec. 7, 2005

Re: [Wlug] Grub problems after imaging drive

by Andy Stewart

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Dick Goodman wrote: > I recently configured a RedHat 9 system with OpenVPN . The original > configuration was done on an old junk box. This is a single boot w/grub > system > > As of last week I knew nothing about grub; I now know marginally more. > > As it was working successfully, it was decided to build a new box for it. > The hard drive was imaged with Ghost Corporate 8.x and restored onto the > new drive. There are some known issues with 8.x and grub > > The grub screen comes up on booting the new box, but when selecting the > (one) entry for RH9, after a short pause it comes back to the grub > screen. I read the grub manual, and from the grub screen did c-command, > then > > root (hd0,0) > setup (hd0) > quit > > The messages after setup did not look like error messages. The behavior > is the same, although I see a message about stage 1.5 flicker by. > I figured out how to look at the hard drive with Knoppix 3.8.2 Live CD > and the partitions and contents look "ok", so it appears to just be a > boot issue. > > How do I resolve this? What additional information do you need? Is there > a better way to clone Linux drive -> Linux drive? > > Dick > _______________________________________________ > Wlug mailing list > Wlug(a)mail.wlug.org > http://mail.wlug.org/mailman/listinfo/wlug > Here's what I use for boot commands in GRUB on my system. Its SuSE, but I don't think it should make a difference. root (hd0,0)/vmlinuz <boot parameters> initrd (hd0,0)/initrd - From a GRUB command line, make sure (by using the TAB key) that (hd0,0) is a legitimate partition, and that it can find /vmlinuz (or whatever kernel image you are using). If you need initrd, you can use the same trick with the TAB key to get a poor man's directory listing. After you enter those lines, or edit the existing lines to make them look as above, boot it and you should at least get the kernel to start. You may need to specify "root=/dev/xxx" as one of the boot parameters on the "root" command. If you get a panic when it tries to mount root, it is either because you didn't specify "root=/dev/xxx", or because the code for the root device isn't present in the kernel (for example, a SCSI driver or a reiserfs module, as appropriate). I hope root isn't part of LVM...that's a can of worms you should avoid, but I digress. I hope this helps, Andy - -- Andy Stewart, Founder Worcester Linux Users' Group Worcester, MA, USA http://www.wlug.org -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.5 (GNU/Linux) Comment: Using GnuPG with Thunderbird - http://enigmail.mozdev.org iD8DBQFDlnkCHl0iXDssISsRAuiaAJ0ZhX3Il4sFM2Yt2cCG1IQBZMy11wCfZIcn bPoThROtkjrTtXGgaHq2Vms= =J3lU -----END PGP SIGNATURE-----

Dec. 7, 2005

Grub problems after imaging drive

by Dick Goodman

I recently configured a RedHat 9 system with OpenVPN . The original configuration was done on an old junk box. This is a single boot w/grub system As of last week I knew nothing about grub; I now know marginally more. As it was working successfully, it was decided to build a new box for it. The hard drive was imaged with Ghost Corporate 8.x and restored onto the new drive. There are some known issues with 8.x and grub The grub screen comes up on booting the new box, but when selecting the (one) entry for RH9, after a short pause it comes back to the grub screen. I read the grub manual, and from the grub screen did c-command, then root (hd0,0) setup (hd0) quit The messages after setup did not look like error messages. The behavior is the same, although I see a message about stage 1.5 flicker by. I figured out how to look at the hard drive with Knoppix 3.8.2 Live CD and the partitions and contents look "ok", so it appears to just be a boot issue. How do I resolve this? What additional information do you need? Is there a better way to clone Linux drive -> Linux drive? Dick

Dec. 7, 2005

Re: [Wlug] SSH without passwords

by Mike Leo

Just for the record, i did not have to make any changes from the default sshd_config file to get this to work. --- Chuck Anderson <cra(a)WPI.EDU> wrote: > Make sure public key auth is enabled on the client > and server: > > /etc/ssh/sshd_config: > > RSAAuthentication yes > PubkeyAuthentication yes > AuthorizedKeysFile .ssh/authorized_keys > > /etc/ssh/ssh_config: > > Host * > RSAAuthentication yes > PubkeyAuthentication yes > > (these are defaults, and so they are commented out > in my files) > > SSH version 1 uses RSAAuthentication, SSH version 2 > uses > PubkeyAuthentication. > > Make sure the perms on the directories and files are > tight enough > (sshd checks): > > chmod 700 ~/.ssh > chmod 600 ~/.ssh/* > > > Finally, are both the server/client the same > implementation of SSH? > SSH.COM uses slightly different formats than OpenSSH > for the public > keys. ssh-keygen can convert between the formats. > > On Wed, Nov 30, 2005 at 01:27:54PM -0800, Mike Leo > wrote: > > i do exactly that, yet it still prompts me for a > > password when ssh'ing. > > > > thoughts? > > > > --- Mike Frysinger <vapier(a)gentoo.org> wrote: > > > > > On Wed, Nov 30, 2005 at 12:37:19PM -0800, Mike > Leo > > > wrote: > > > > Basically we are ssh-keygen -t (dsa/rsa) the > keys, > > > > copy them to the "remote" servers ~/.ssh/ > > > > > > what are you copying ? for example, i create my > dsa > > > keys: > > > ~/.ssh/id_dsa ~/.ssh/id_dsa.pub > > > then i export my pub key to the remote server: > > > $ scp ~/.ssh/id_dsa.pub remotebox:~/ > > > $ ssh remotebox # <- enter my pw > > > $ cat ~/id_dsa.pub >> ~/.ssh/authorized_keys > > > $ rm ~/id_dsa.pub > > > $ logout > > > $ ssh remotebox # <- no pw needed > > > > > > > There are conflicting doc's at this > point...some > > > say > > > > you need an ssh-agent, some don't mention it. > > > Some > > > > use passphrases, some don't. But if i have to > > > enter > > > > an ssh passphrase everytime, why not just use > the > > > > account password? > > > > > > passphrases are not required, but many people > like > > > to use them > > > > > > ssh-agent allows you to cache the passphrase for > a > > > certain amount > > > of time, thus finding some ground between the > > > 'always use pw' and the > > > 'never use pw' ground of authentication > > > -mike > > > _______________________________________________ > > > Wlug mailing list > > > Wlug(a)mail.wlug.org > > > http://mail.wlug.org/mailman/listinfo/wlug > > > > > > > _______________________________________________ > > Wlug mailing list > > Wlug(a)mail.wlug.org > > http://mail.wlug.org/mailman/listinfo/wlug > > -- > Chuck R. Anderson <cra(a)wpi.edu> / > http://angus.ind.wpi.edu/~cra/ > PGP Fingerprint: EBA3 A106 7C93 FA07 8E15 3AC2 C367 > A0F9 49BB 5886 > _______________________________________________ > Wlug mailing list > Wlug(a)mail.wlug.org > http://mail.wlug.org/mailman/listinfo/wlug >

Dec. 1, 2005

Re: [Wlug] SSH without passwords

by Mike Leo

YAAHAHAHAHAHAA!!! Accurate Oracle documents??!?!? HAHHAHAHAAHA --- Jared Greenwald <greenwaldjared(a)gmail.com> wrote: > Oh yea, I forgot that. That one bit me the first 10 > times I did > this... Strange, though that if this is a RAC > requirement it wouldn't > be outlined in the RAC docs... > > -Jared > > On 11/30/05, Mike Leo <mleo963(a)yahoo.com> wrote: > > I got it!! > > > > weird, but i had to change the permissions on the > auth > > file to 640, and then it worked. > > > > Weird is that with less restrictive permissions > (644) > > it failed, but more secure works. > > > > Anyway, thanks for the feedback! > > > > --- Mike Frysinger <vapier(a)gentoo.org> wrote: > > > > > On Wed, Nov 30, 2005 at 12:37:19PM -0800, Mike > Leo > > > wrote: > > > > Basically we are ssh-keygen -t (dsa/rsa) the > keys, > > > > copy them to the "remote" servers ~/.ssh/ > > > > > > what are you copying ? for example, i create my > dsa > > > keys: > > > ~/.ssh/id_dsa ~/.ssh/id_dsa.pub > > > then i export my pub key to the remote server: > > > $ scp ~/.ssh/id_dsa.pub remotebox:~/ > > > $ ssh remotebox # <- enter my pw > > > $ cat ~/id_dsa.pub >> ~/.ssh/authorized_keys > > > $ rm ~/id_dsa.pub > > > $ logout > > > $ ssh remotebox # <- no pw needed > > > > > > > There are conflicting doc's at this > point...some > > > say > > > > you need an ssh-agent, some don't mention it. > > > Some > > > > use passphrases, some don't. But if i have to > > > enter > > > > an ssh passphrase everytime, why not just use > the > > > > account password? > > > > > > passphrases are not required, but many people > like > > > to use them > > > > > > ssh-agent allows you to cache the passphrase for > a > > > certain amount > > > of time, thus finding some ground between the > > > 'always use pw' and the > > > 'never use pw' ground of authentication > > > -mike > > > _______________________________________________ > > > Wlug mailing list > > > Wlug(a)mail.wlug.org > > > http://mail.wlug.org/mailman/listinfo/wlug > > > > > > > _______________________________________________ > > Wlug mailing list > > Wlug(a)mail.wlug.org > > http://mail.wlug.org/mailman/listinfo/wlug > > > > _______________________________________________ > Wlug mailing list > Wlug(a)mail.wlug.org > http://mail.wlug.org/mailman/listinfo/wlug >

Dec. 1, 2005

Re: [Wlug] SSH without passwords

by Chuck Anderson

I usually create service-specific unpriviliged accounts with their own SSH keys with no passphrases for this purpose. If there are many services/users that need to log in between the boxes, and you don't mind the boxes trusting each other completely, you can use HostBasedAuthentication, which is sort of like rhosts, but with SSH Public Key authentication. Then any user can SSH between boxes that are in /etc/ssh/shosts.equiv with no password, and no user-specific key/passphrase required. On Wed, Nov 30, 2005 at 01:38:42PM -0800, Mike Leo wrote: > that was all good info...thanks. > > We need to ssh via a service so we can't use a > username/password scheme, and, well, it should work!! > > also, oracle requires this ability to setup their > Oracle RAC database, to/from each node in the cluster.

Dec. 1, 2005

Re: [Wlug] SSH without passwords

by Jared Greenwald

Oh yea, I forgot that. That one bit me the first 10 times I did this... Strange, though that if this is a RAC requirement it wouldn't be outlined in the RAC docs... -Jared On 11/30/05, Mike Leo <mleo963(a)yahoo.com> wrote: > I got it!! > > weird, but i had to change the permissions on the auth > file to 640, and then it worked. > > Weird is that with less restrictive permissions (644) > it failed, but more secure works. > > Anyway, thanks for the feedback! > > --- Mike Frysinger <vapier(a)gentoo.org> wrote: > > > On Wed, Nov 30, 2005 at 12:37:19PM -0800, Mike Leo > > wrote: > > > Basically we are ssh-keygen -t (dsa/rsa) the keys, > > > copy them to the "remote" servers ~/.ssh/ > > > > what are you copying ? for example, i create my dsa > > keys: > > ~/.ssh/id_dsa ~/.ssh/id_dsa.pub > > then i export my pub key to the remote server: > > $ scp ~/.ssh/id_dsa.pub remotebox:~/ > > $ ssh remotebox # <- enter my pw > > $ cat ~/id_dsa.pub >> ~/.ssh/authorized_keys > > $ rm ~/id_dsa.pub > > $ logout > > $ ssh remotebox # <- no pw needed > > > > > There are conflicting doc's at this point...some > > say > > > you need an ssh-agent, some don't mention it. > > Some > > > use passphrases, some don't. But if i have to > > enter > > > an ssh passphrase everytime, why not just use the > > > account password? > > > > passphrases are not required, but many people like > > to use them > > > > ssh-agent allows you to cache the passphrase for a > > certain amount > > of time, thus finding some ground between the > > 'always use pw' and the > > 'never use pw' ground of authentication > > -mike > > _______________________________________________ > > Wlug mailing list > > Wlug(a)mail.wlug.org > > http://mail.wlug.org/mailman/listinfo/wlug > > > > _______________________________________________ > Wlug mailing list > Wlug(a)mail.wlug.org > http://mail.wlug.org/mailman/listinfo/wlug >

Nov. 30, 2005

Re: [Wlug] SSH without passwords

by Mike Leo

I got it!! weird, but i had to change the permissions on the auth file to 640, and then it worked. Weird is that with less restrictive permissions (644) it failed, but more secure works. Anyway, thanks for the feedback! --- Mike Frysinger <vapier(a)gentoo.org> wrote: > On Wed, Nov 30, 2005 at 12:37:19PM -0800, Mike Leo > wrote: > > Basically we are ssh-keygen -t (dsa/rsa) the keys, > > copy them to the "remote" servers ~/.ssh/ > > what are you copying ? for example, i create my dsa > keys: > ~/.ssh/id_dsa ~/.ssh/id_dsa.pub > then i export my pub key to the remote server: > $ scp ~/.ssh/id_dsa.pub remotebox:~/ > $ ssh remotebox # <- enter my pw > $ cat ~/id_dsa.pub >> ~/.ssh/authorized_keys > $ rm ~/id_dsa.pub > $ logout > $ ssh remotebox # <- no pw needed > > > There are conflicting doc's at this point...some > say > > you need an ssh-agent, some don't mention it. > Some > > use passphrases, some don't. But if i have to > enter > > an ssh passphrase everytime, why not just use the > > account password? > > passphrases are not required, but many people like > to use them > > ssh-agent allows you to cache the passphrase for a > certain amount > of time, thus finding some ground between the > 'always use pw' and the > 'never use pw' ground of authentication > -mike > _______________________________________________ > Wlug mailing list > Wlug(a)mail.wlug.org > http://mail.wlug.org/mailman/listinfo/wlug >

Nov. 30, 2005

Re: [Wlug] SSH without passwords

by Chuck Anderson

Make sure public key auth is enabled on the client and server: /etc/ssh/sshd_config: RSAAuthentication yes PubkeyAuthentication yes AuthorizedKeysFile .ssh/authorized_keys /etc/ssh/ssh_config: Host * RSAAuthentication yes PubkeyAuthentication yes (these are defaults, and so they are commented out in my files) SSH version 1 uses RSAAuthentication, SSH version 2 uses PubkeyAuthentication. Make sure the perms on the directories and files are tight enough (sshd checks): chmod 700 ~/.ssh chmod 600 ~/.ssh/* Finally, are both the server/client the same implementation of SSH? SSH.COM uses slightly different formats than OpenSSH for the public keys. ssh-keygen can convert between the formats. On Wed, Nov 30, 2005 at 01:27:54PM -0800, Mike Leo wrote: > i do exactly that, yet it still prompts me for a > password when ssh'ing. > > thoughts? > > --- Mike Frysinger <vapier(a)gentoo.org> wrote: > > > On Wed, Nov 30, 2005 at 12:37:19PM -0800, Mike Leo > > wrote: > > > Basically we are ssh-keygen -t (dsa/rsa) the keys, > > > copy them to the "remote" servers ~/.ssh/ > > > > what are you copying ? for example, i create my dsa > > keys: > > ~/.ssh/id_dsa ~/.ssh/id_dsa.pub > > then i export my pub key to the remote server: > > $ scp ~/.ssh/id_dsa.pub remotebox:~/ > > $ ssh remotebox # <- enter my pw > > $ cat ~/id_dsa.pub >> ~/.ssh/authorized_keys > > $ rm ~/id_dsa.pub > > $ logout > > $ ssh remotebox # <- no pw needed > > > > > There are conflicting doc's at this point...some > > say > > > you need an ssh-agent, some don't mention it. > > Some > > > use passphrases, some don't. But if i have to > > enter > > > an ssh passphrase everytime, why not just use the > > > account password? > > > > passphrases are not required, but many people like > > to use them > > > > ssh-agent allows you to cache the passphrase for a > > certain amount > > of time, thus finding some ground between the > > 'always use pw' and the > > 'never use pw' ground of authentication > > -mike > > _______________________________________________ > > Wlug mailing list > > Wlug(a)mail.wlug.org > > http://mail.wlug.org/mailman/listinfo/wlug > > > > _______________________________________________ > Wlug mailing list > Wlug(a)mail.wlug.org > http://mail.wlug.org/mailman/listinfo/wlug -- Chuck R. Anderson <cra(a)wpi.edu> / http://angus.ind.wpi.edu/~cra/ PGP Fingerprint: EBA3 A106 7C93 FA07 8E15 3AC2 C367 A0F9 49BB 5886

Nov. 30, 2005

Re: [Wlug] SSH without passwords

by Mike Leo

that was all good info...thanks. We need to ssh via a service so we can't use a username/password scheme, and, well, it should work!! also, oracle requires this ability to setup their Oracle RAC database, to/from each node in the cluster. --- Chuck Anderson <cra(a)WPI.EDU> wrote: > On Wed, Nov 30, 2005 at 12:37:19PM -0800, Mike Leo > wrote: > > There are conflicting doc's at this point...some > say > > you need an ssh-agent, some don't mention it. > Some > > use passphrases, some don't. But if i have to > enter > > an ssh passphrase everytime, why not just use the > > account password? > > > Passwords get sent tunneled through the encrypted > SSH connection. A > trojaned ssh server could steal your password. > Passphrases and > private keys are never sent anywhere outside of your > box (unless you > want them to). > > If an account password gets compromised, you may > have to change it on > many boxes, and it may be shared with other > unrelated accounts > elsewhere. If a passphrase gets compromised, it > doesn't allow anyone > to do anything without your private key file--you > need both the > private key and the passphrase. > > You can share your passphrase for many different > private keys, but > still have different passwords on unrelated remote > systems. > > You can cache the passphrase in the memory of your > local box > (ssh-agent) so you don't need to enter anything to > ssh to remote > boxes. > > Using a private key with a blank passphrase means > someone could steal > your private key file and use it to log in as you. > This weakens the > requirement for having to steal both the private key > and the > passphrase. Since the private key sits on disk for > a long time, > someone down the road could steal it and you may > never know. This is > even worse if you use a network filesystem for your > home directory. > The passphrase encrypts your private key. > _______________________________________________ > Wlug mailing list > Wlug(a)mail.wlug.org > http://mail.wlug.org/mailman/listinfo/wlug >

Nov. 30, 2005

Re: [Wlug] SSH without passwords

by Mike Leo

i do exactly that, yet it still prompts me for a password when ssh'ing. thoughts? --- Mike Frysinger <vapier(a)gentoo.org> wrote: > On Wed, Nov 30, 2005 at 12:37:19PM -0800, Mike Leo > wrote: > > Basically we are ssh-keygen -t (dsa/rsa) the keys, > > copy them to the "remote" servers ~/.ssh/ > > what are you copying ? for example, i create my dsa > keys: > ~/.ssh/id_dsa ~/.ssh/id_dsa.pub > then i export my pub key to the remote server: > $ scp ~/.ssh/id_dsa.pub remotebox:~/ > $ ssh remotebox # <- enter my pw > $ cat ~/id_dsa.pub >> ~/.ssh/authorized_keys > $ rm ~/id_dsa.pub > $ logout > $ ssh remotebox # <- no pw needed > > > There are conflicting doc's at this point...some > say > > you need an ssh-agent, some don't mention it. > Some > > use passphrases, some don't. But if i have to > enter > > an ssh passphrase everytime, why not just use the > > account password? > > passphrases are not required, but many people like > to use them > > ssh-agent allows you to cache the passphrase for a > certain amount > of time, thus finding some ground between the > 'always use pw' and the > 'never use pw' ground of authentication > -mike > _______________________________________________ > Wlug mailing list > Wlug(a)mail.wlug.org > http://mail.wlug.org/mailman/listinfo/wlug >

Nov. 30, 2005

Re: [Wlug] SSH without passwords

by Chuck Anderson

On Wed, Nov 30, 2005 at 12:37:19PM -0800, Mike Leo wrote: > There are conflicting doc's at this point...some say > you need an ssh-agent, some don't mention it. Some > use passphrases, some don't. But if i have to enter > an ssh passphrase everytime, why not just use the > account password? Passwords get sent tunneled through the encrypted SSH connection. A trojaned ssh server could steal your password. Passphrases and private keys are never sent anywhere outside of your box (unless you want them to). If an account password gets compromised, you may have to change it on many boxes, and it may be shared with other unrelated accounts elsewhere. If a passphrase gets compromised, it doesn't allow anyone to do anything without your private key file--you need both the private key and the passphrase. You can share your passphrase for many different private keys, but still have different passwords on unrelated remote systems. You can cache the passphrase in the memory of your local box (ssh-agent) so you don't need to enter anything to ssh to remote boxes. Using a private key with a blank passphrase means someone could steal your private key file and use it to log in as you. This weakens the requirement for having to steal both the private key and the passphrase. Since the private key sits on disk for a long time, someone down the road could steal it and you may never know. This is even worse if you use a network filesystem for your home directory. The passphrase encrypts your private key.

Nov. 30, 2005

Re: [Wlug] SSH without passwords

by Jared Greenwald

I've used this setup in the past... http://www.astro.caltech.edu/~mbonati/WIRC/manual/DATARED/setting_up_no-pas… On 11/30/05, Mike Leo <mleo963(a)yahoo.com> wrote: > I remember someone talking about sharing keys between > systems so you can ssh around at will without needing > the password.... > > we are trying to do this, but are having a hard time. > Anyone have a good doc (or willing to write one) about > how to do this? > > Basically we are ssh-keygen -t (dsa/rsa) the keys, > copy them to the "remote" servers ~/.ssh/ > > There are conflicting doc's at this point...some say > you need an ssh-agent, some don't mention it. Some > use passphrases, some don't. But if i have to enter > an ssh passphrase everytime, why not just use the > account password? > > Any advise would be helpful... > > thanks as always.. > Mike > _______________________________________________ > Wlug mailing list > Wlug(a)mail.wlug.org > http://mail.wlug.org/mailman/listinfo/wlug >

Nov. 30, 2005

Re: [Wlug] SSH without passwords

by Mike Frysinger

On Wed, Nov 30, 2005 at 12:37:19PM -0800, Mike Leo wrote: > Basically we are ssh-keygen -t (dsa/rsa) the keys, > copy them to the "remote" servers ~/.ssh/ what are you copying ? for example, i create my dsa keys: ~/.ssh/id_dsa ~/.ssh/id_dsa.pub then i export my pub key to the remote server: $ scp ~/.ssh/id_dsa.pub remotebox:~/ $ ssh remotebox # <- enter my pw $ cat ~/id_dsa.pub >> ~/.ssh/authorized_keys $ rm ~/id_dsa.pub $ logout $ ssh remotebox # <- no pw needed > There are conflicting doc's at this point...some say > you need an ssh-agent, some don't mention it. Some > use passphrases, some don't. But if i have to enter > an ssh passphrase everytime, why not just use the > account password? passphrases are not required, but many people like to use them ssh-agent allows you to cache the passphrase for a certain amount of time, thus finding some ground between the 'always use pw' and the 'never use pw' ground of authentication -mike

Nov. 30, 2005