cat pants's questions

If you telnet to an ssh server, it will establish a connection and return a string, something like SSH-2.0-OpenSSH.... etc.

Something similar happens if you connect to a mysql server.

What exactly is the name of the string that the service returns? It's not a "header", since we aren't talking about http(s) here.

Similarly, it's also possible to send commands via telnet, for example, you can connect to an email server and send an email this way if you wanted to. What is the name of the commands one would send? They aren't exactly "POST" requests, again, since we aren't using http(s) here.

If you set CLIFF_FIT_WIDTH=1, openstack cli will fit table output to the screen width.

However, this breaks if you try and pipe to less.

It seems like a possible workaround could be: alias openstack='openstack --max-width "$(tput cols)"' but this seems hacky. Is there a flag or env var for openstack cli I missed so that I can pipe the output to less without the width breaking?

Assume you have two servers in a private network.

Server 1: ip: 10.0.0.10, lives in the /24 subnet 10.0.0.x.

Server 2: ip: 10.0.1.20, lives in the /24 subnet 10.0.1.x.

Assume these two servers cannot reach each other, there is no route. I would normally say "10.0.0.10 is not routable from 10.0.1.20" but I realize now that this might not be the proper terminology.

It seems like the term "routable" is actually used to refer to the difference between public and private ips, ie, "8.8.8.8 is routable, 10.2.10.129 is not".

So what exactly is the correct term for my original example? "Reachable"? "Reachable" doesn't really sound right for some reason.

So far Serverspec is working out great. I'm testing my servers, everything looks good.

Let's say I want to test my LDAP cluster via running a few LDAP commands from my local workstation, say ldapsearch. The reason I would do this on my workstation rather than any of the servers is to ensure everything works remotely, including load balancing.

What's the convention? How is this accomplished? What changes would I have to make to my Rakefile? I have generated a Rakefile via serverspec-init. Any examples of this somewhere?

I have been doing some VM testing. I have created and destroyed a large number of VMs on my subnet to test fresh provisioning via puppet. However, it looks like Ubuntu doesn't free a DHCP lease when the system is shut down, and the DHCP lease time is a week. So I have reached a point where I can't get a DHCP lease with a new VM. I could have released the leases on the test VMs manually had I known, but I need to release those leases so I can get my free IPs back. DHCP server is serving some production servers as well, so I can't just nuke all the leases and call it a day.

DHCP server OS is Ubuntu 12.04.4. Using dhcpd for the DHCP server.

Given access to a single node that is being managed by puppet enterprise, I want to view the list of resources that puppet is managing. How do I do that? Node OS is Ubuntu 14.04. Interested in PE versions 2, 3, and 2015.2.

Thanks!

I'm trying to configure OpenNebula to use the DHCP server that already exists on my network. Yes, I already know that OpenNebula manages virtual mac addresses rather than IP addresses, but that doesn't tell me how to get this working. ;)

My guests and hosts are both CentOS, so I would imagine all that needs to be done is configure contextualization so that BOOTPROTO=dhcp is dumped into /etc/sysconfig/network-scripts/ifcfg-eth0.

1. How do I configure contextualization so that this happens? Do I just modify my template in a certain way? If so, how is that done?
2. Once I configure my template with these new contextualization settings, how should I configure my virtual network in ONE?

It seems like this should be easy to do, as this should appear to be simpler than managing a bunch of static IPs for vms, and you would think that this is a common use case. However, googleing so far has turned up very little.

Thanks!!

Edit: My DHCP server successfully gives my vm an ip address if I set BOOTPROTO=dhcp and DHCP_HOSTNAME=foo manually and restart networking on my vm. Which is fine, I would like to be able to set the hostnames of the vms I spin up too.

Now it's just a matter of determining how to make ONE do these things automatically/via the web interface or CLI tools. Also ONE still lists the IP address of the original lease, rather than the IP that DHCP gave my VM. It would be nice to get that issue fixed too.

Assuming the system is a red hat variant, x86 architecture. Assume no cooling issues.

Is it possible for a very high load on the machine to cause it to reboot?

I understand that a machine make become unresponsive, certainly. But can it actually reboot?

If so, how does this occur?

I'm trying to write a script to enable IPMI on a ton of machines without having to hook up a KVM to them one by one. Is it possible to change the BIOS settings from Linux? OS is SL6.

I understand that each machine will likely need to be power cycled, but I can do that programmatically of course.

Documentation here says three: http://docs.mongodb.org/manual/tutorial/deploy-replica-set/

"A replica set requires three distinct systems..."

Whereas the documentation here says two: http://docs.mongodb.org/manual/core/replication/

"Most replica sets consists of two or more mongod instances..."

Anyone know which is correct?

dpkg -L lists all the files provided by a package. How is this accomplished with yum?

The operating system is Scientific Linux 6.

I imagine that kill -9 still just sends a signal to a process. If the process is not behaving well, I would imagine that kill -9 would have no effect. Indeed, today for the first time I saw kill -9 have no effect when sent to a stuck ruby process. So here is my question: Is there some harsher way to kill a process?

It appears that I am able to successfully do a pvcreate on top of a raw block device, without ever taking the step of creating a partition table. I am then able to create a volume group, logical volume, and finally a filesystem, mount it, and test via dd.

It appears to work, but I need a sanity check. Is this a bad idea?

How do I create a GPT or MBR partition table on top of a raw block device?

How do I use parted to show what sort of partition table is in use? I have tried doing:

parted, select /dev/sdb, print and I get:

Error: /dev/sdb: unrecognised disk label

Yet the drive is currently in use and I can read and write to it. Is that the expected output when doing LVM on top of a raw block device without a partition table? Any thoughts?

Thanks!

I think I have found something that I need from the Linux kernel that is not currently implemented.

I need a way to set a max thread limit per process.

Is this possible?

I have remote ssh access and root access. I do not have physical access. I'm not looking for solutions involving booting into anything, I want to do this from what is currently running.

OS is SL6. Is there a way to load everything needed into RAM, and use dd or similar to securely wipe the entire disk? Obviously this will result in a non-functioning box in the end, my intended result.

It seems like this should be possible.

Two more interesting additions:

1. Be able to ssh in, run screen, run the dd command and detach. Log in a week later once it has finished. :)

2. Somehow have a progress bar?

Update: I am now going with the chroot option. Currently doing:

mkdir /dev/shm/ramdisk/ && cd ramdisk && mkdir bin lib64 && cd /lib64 && cp ld-linux-x86-64.so.2 libc.so.6 libdl.so.2 libpthread.so.0 librt.so.1 libtinfo.so.5 /dev/shm/ramdisk/lib64 && cd /bin && cp bash dd /dev/shm/ramdisk/bin && cd /dev/shm/ramdisk && chroot .

Which works(!) but I still need /dev/zero and /dev/sda. Any ideas there?

Update 2012-07-20:

mkdir /dev/shm/ramdisk/ && cd /dev/shm/ramdisk && mkdir bin lib64 && cd /lib64 && cp ld-linux-x86-64.so.2 libc.so.6 libdl.so.2 libpthread.so.0 librt.so.1 libtinfo.so.5 /dev/shm/ramdisk/lib64 && cd /bin && cp bash dd /dev/shm/ramdisk/bin && mkdir /dev/shm/ramdisk/dev && cd /dev/shm/ramdisk/dev && cp -a /dev/zero . && cp -a /dev/sda . && cd .. && chroot . dd if=/dev/zero of=/dev/sda bs=1M

Which appears to be doing something, but I would like to have some sort of progress indicator if possible, as well as a way to detach and then establish a new ssh connection later.

If a logrotate config is specified with "size" and "daily" parameters, which one takes precedence? Where is this documented? I would like these rotations to occur as a boolean OR operation, ie, if the logs are a day old they get rotated, OR if they are larger than a certain size they will also get rotated. However, logrotate is currently only using the "size" directive, and appears to be ignoring the "daily" directive. Logrotate is set up to run every hour. OS is linux, Red Hat and Debian derivatives.

Also, I am specifying "daily" first, then "size" from the start of the file. Not sure if the order matters, but in any case, one has to come first in the config file...

Thanks!

/opt/MegaCli -CfgDsply -a0 | less RAID Level : Primary-1, Secondary-3, RAID Level Qualifier-0

Almost positive this is not running a RAID3, my guess is a RAID 10, where "Primary" means what is being done in the "spans" (span being Mega Cli term for the first RAID operation blocks) and then the "RAID Level Qualifier" is the RAID level operation being done on top of the spans, and finally, "Secondary-3" means that there are 3 spans being RAID0'd across. This interpretation matches the disk space sanity checks, indeed the total capacity of the array is that of three physical drives. However, this interpretation and output syntax is convoluted to the point where a clarification is definitely needed.

If a switch gets rebooted and the settings haven't been "wr"d, when it comes back up things will be all wrong. I want to see what the current vlan settings are vs what has been "wr"d.

Thanks!!

Edit:

Er... I meant like the difference between current show int status and what will get set if the switch gets rebooted. Thanks!

Running MySQL on a box with 32 gigs of RAM. Swap is 99% full, and there is about 200 MB of RAM free. MySQL is the culprit of course. What happens when both RAM and swap are completely filled? Thanks!

I have nagios alerts set up to come through jabber with an http link to ack.

Is is possible there is a script I can run from a terminal on a remote workstation that takes the hostname as a parameter and acks the alert?

./ack hostname

The benefit, while seemingly mundane, is threefold. First, take http load off nagios. Secondly, nagios http pages can take up to 10-20 seconds to load, so I want to save time there. Thirdly, avoiding slower use of mouse + web interface + firefox/other annoyingly slow browser.

Ideally, I would like a script bound to a keyboard shortcut that simply acks the most recent alert. Finally, I want to take the inputs from a joystick, buttons and whatnot, and connect one to a big red button bound to the script so I can just ack the most recent nagios alert by hitting the button lol. (It would be rad too if the button had a screen on the enclosure that showed the text of the alert getting acked lol)

Make fun of me all you want, but this is actually something that would be useful to me. If I can save five seconds per alert, and I get 200 alerts per day I need to ack, that's saving me 15 minutes a day. And isn't the whole point of the sysadmin to automate what can be automated?

Thanks!