Neil's questions

I have the following vanilla Ansible configuration that helps go through a slow Bastion:

[ssh_connection]
ssh_args=-o PasswordAuthentication=no -o ConnectTimeout=60s -o ControlMaster=auto -o ControlPersist=60s -o ControlPath=/tmp/ansible-ssh-%h-%p-%r

However, when using the Mitogen plugin with this configuration:

[defaults]
# https://mitogen.networkgenomics.com/ansible_detailed.html
strategy_plugins = mitogen-0.2.9/ansible_mitogen/plugins/strategy
strategy = mitogen_linear

The timeout in the [ssh_connection] section clearly isn't used.

The Mitogen SSH documentation alludes to some SSH configuration, but it's unclear where to set these variables.

When I create a MongoDB database with this script:

#!/bin/bash

javascript='
db.dropUser("admin");
db.createUser({
    user: "admin",
    pwd: "password",
    roles: [
        {role: "userAdminAnyDatabase", db: "admin"}
    ]
});
db.getSiblingDB("example").empty.save({"empty": 0});
'

docker-compose exec mongodb mongo --eval "${javascript}"

I can successfully login with the mongo shell and command-line parameters:

$ mongo --host docker-machine -u admin -p password
MongoDB shell version v3.4.10
connecting to: mongodb://docker-machine:27017/
MongoDB server version: 3.4.10

But with what seems like the equivalent connection URI, the connection fails:

$ mongo 'mongodb://admin:password@docker-machine/'
MongoDB shell version v3.4.10
connecting to: mongodb://admin:password@docker-machine/
2017-12-06T21:17:47.297-0700 E QUERY    [thread1] Error: Authentication failed. :
connect@src/mongo/shell/mongo.js:237:13
@(connect):1:6
exception: connect failed

And the MongoDB log shows:

2017-12-07T04:16:27.703+0000 I ACCESS   [conn100]
    SCRAM-SHA-1 authentication failed for admin on admin from client
    10.211.55.2:52496 ; AuthenticationFailed: SCRAM-SHA-1 authentication
    failed, storedKey mismatch

What's going on?

How can I log all commands executed on Linux, including their command-line arguments (parameters)?

So, for example, if someone runs:

rm -rf /tmp/foo

I would see a log entry similar to this:

2016-01-01 18:00:00 user=bob command='rm -rf /tmp/foo'

And not just this:

2016-01-01 18:00:00 user=bob command='rm'

I have only been able to find uses of auditd which don't log command-line arguments (parameters). Is there a way to properly configure auditd to record this? It looks like FreeBSD has a way to set an argv policy, but this doesn't seem to be present in Debian derivatives.

I have the following YAML in an Ansible playbook:

offset: "{{ publicip | regex_replace('^.*\\.([0-9]+)$', '\\\\1') | int % (step-1) + 1 }}"
cron_minute_list: "{% for i in range(offset, 60, step) %}{{ i }},{% endfor %}"

But when I run the playbook, I get this error:

fatal: [default] => Failed to template */{{ cron_minute_list | regex_replace('.$', '') }}:
  Failed to template {% for i in range(int_offset, 60, step) %}{{ i }},{% endfor %}:
    an unexpected type error occurred. Error was an integer is required

I get other errors when I try using int(offset) in the range statement. Appending a | int to the end of the offset declaration makes no difference.

There seems to be no way to set the type of offset to be an integer rather than a string. How can I fix this?

If there's another way to make such a cron schedule, so I don't have to worry about this, that would also be a good answer.

I have an Ansible task that makes a URI request to a website to get a JSON response. I want Ansible to do something if the nested JSON variable is defined, and something else if it isn't.

- name: Get JSON from the Interwebs
  uri: url="http://whatever.com/jsonresponse" return_content=yes
  register: json_response

- name: Write nested JSON variable to disk
  copy: content={{json_response.json.nested1.nested2}} dest="/tmp/foo.txt"

Note that using ignore_errors only works for the task's command failing, not for checking undefined values in nested data structures within a Jinja template. So if json_response.json.nested1.nested2 isn't defined, this task will still fail despite ignore_errors=yes being set.

How do I get this playbook to store some default value in /tmp/foo.txt if the request fails, or if the request doesn't have the right nested value defined?

I'm trying to get Varnish to serve up cached objects with an expired TTL when requesting a new copy of the object from the backend returns a 503 error.

There is a Varnish Grace feature which will do this when the backend is unhealthy, but it doesn't work when the backend is passing its health check.

I'm loading up Nexus on a VM with all outbound ports locked down. I need to know what outbound ports Nexus uses to do whatever it does in all scenarios.

Let's assume the repositories it connects to use their corresponding standard ports.

CentOS 6.0 comes with the ability to set its TERM to screen-256color. It doesn't work in CentOS 5.7, though.

How can you get CentOS 5.7 to support screen-256color?

I set up a share like this:

[global]
    security = user
    map to guest = Bad Password
    usershare allow guests = yes

[vms]
    comment = VirtualBox Virtual Machines
    path = /home/neil/VirtualBox/HardDisks
    guest ok = yes
    read only = yes

And when I access the share as myself, and type in my password, it works fine:

$ smbclient //neil-ubuntu/vms -U neil
Enter neil's password: 
Domain=[SHUTTERSTOCK] OS=[Unix] Server=[Samba 3.4.0]
smb: \>

But when I access it as guest, it doesn't work:

$ smbclient //neil-ubuntu/vms -U guest
Enter guest's password: 
Domain=[SHUTTERSTOCK] OS=[Unix] Server=[Samba 3.4.0]
tree connect failed: NT_STATUS_BAD_NETWORK_NAME

Regardless of what password I type in.

Does anyone know why?

Also, why does smbclient print such useless error messages?

I'm trying to measure the total amount of disk writing and reading that is done to a particular volume by a particular process over a specified duration.

I've found iotop, which can output IO every second for a particular process like this:

iotop --batch --pid $(pidof my_process)

Where you can specify x iterations with -n x.

But then I have to filter out the actual number, and tally it up myself.

Is there an easier way to do this?

I'm trying to figure out what the CPU usage of Firefox is at any given moment in time, and pipe that number to another script.

So, top is not the answer, since its output is in a chart and polluted with special characters.

I've also tried:

ps -eo pid,cp | grep $(pidof firefox)

But that gives CPU usage divided by CPU time, which is not the same that top or Gkrellm report.

So, how can I write a one-liner that gets the CPU usage of a particular PID?

I'm using VMware Server 2.0.1-156745.i386 for Linux on Ubuntu 8.10.

When I run "vmware", it brings up what is supposed to be the login page in a browser, but it just loads a blank page.

This is the address:

https://127.0.0.1:8333/ui/

Sometimes the login page comes back if you reload it a bunch of times, but this time it won't. Doing this also doesn't help:

/etc/init.d/vmware restart

Does anyone know why this happens, and how to fix it?

If I run a program from the shell, and it segfaults:

$ buggy_program
Segmentation fault

It will tell me, however, is there a way to get programs to print a backtrace, perhaps by running something like this:

$ print_backtrace_if_segfault buggy_program
Segfault in main.c:35
(rest of the backtrace)

I'd also rather not use strace or ltrace for that kind of information, as they'll print either way...

I have Ubuntu Intrepid with Samba installed on my machine. I have a basic configuration file included below.

When I try to invoke

smbclient -L localhost

I get the error:

NT_STATUS_CONNECTION_REFUSED

This also happens when trying to invoke smbpasswd.

What are the possible causes of this error?

When I run both:

iptables -L
iptables -t nat -L

They are both empty.

Here is my config file (Running testparm reports that it's ok):

[global]
   workgroup = MSHOME
   server string = %h server (Samba, Ubuntu)
   dns proxy = no
   log file = /var/log/samba/log.%m
   max log size = 1000
   syslog = 0
   panic action = /usr/share/samba/panic-action %d
   encrypt passwords = true
   passdb backend = tdbsam
   obey pam restrictions = yes
   unix password sync = yes
   passwd program = /usr/bin/passwd %u
   passwd chat = *Enter\snew\s*\spassword:* %n\n *Retype\snew\s*\spassword:* %n\n *password\supdated\ssuccessfully* .
   pam password change = yes
   map to guest = bad user
   usershare allow guests = yes
[printers]
   comment = All Printers
   browseable = no
   path = /var/spool/samba
   printable = yes
   guest ok = no
   read only = yes
   create mask = 0700
[print$]
   comment = Printer Drivers
   path = /var/lib/samba/printers
   browseable = yes
   read only = yes
   guest ok = no

I know there is such a thing as a visual bell in Vim that makes the whole screen flash instead of beeping. Several terminal programs also have the same feature.

I'm looking for a similar type of visual bell that will flash all of my screens, on all of my virtual desktops, in X. I've only got headphones at work and my pc speaker is too quiet, so I need some other notification method that will definitely get my attention.

Does anyone know if it exists?

I have set a shared directory on my Windows machine, and given full control permissions to username@workgroup.

When I try to connect to the Windows machine with Linux using smbclient, I get the error NT_STATUS_DUPLICATE_NAME. Here is the transcript:

$ smbclient -U username -W workgroup -L //windows-machine
Enter username's password: 
Domain=[workgroup] OS=[Windows 5.1] Server=[Windows 2000 LAN Manager]
tree connect failed: NT_STATUS_DUPLICATE_NAME

If I intentionally enter the wrong username, password or workgroup, I get a different error: NT_STATUS_LOGON_FAILURE. So it seems like I'm getting the other information right.

I put an entry in /etc/hosts that points windows-machine to its IP address. The NetBIOS name of the windows machine is something different.

Does anyone know what this error means?

I can't get USB devices other than the mouse and keyboard to work in Windows under VMware.

I have Ubuntu Intrepid as my host operating system, and Windows XP Service Pack 2 as the guest operating system. I'm using VMware Server 2.0 for Linux.

Ubuntu and several other distributions have dropped /proc/bus/usb in favour of using something else. VMware has not updated VMWare Server to use the new usb path, and have a workaround listed here:

VMware Support: Mount /proc/bus/usb manually

Even with that workaround, my guest Windows OS still doesn't detect any USB devices that are working fine in Linux.

Does anyone have an idea of what else might be the problem?

I found this hard drive on NewEgg:

Seagate Barracuda 7200.11 ST31500341AS 1.5TB 7200 RPM 32MB Cache SATA 3.0Gb/s 3.5" Internal Hard Drive (bare drive) - OEM

http://www.newegg.com/Product/Product.aspx?Item=N82E16822148337

And there are quite a few substantial bad reviews about the drive freezing periodically. If you search for a bit, you can find several forums with people having problems, but of course forums don't get updated when resolutions to those problems are found.

I'm just wondering, does anyone know what the final verdict regarding the freezing issue with these hard drives is?

I'm on a nokia n810 device, which uses busybox instead of the usual gnu coreutils. Is there a way to get busybox's ls to print in colour?

I know you can do:

sudo modprobe -v some_module

to check the version of /lib/modules/.../some_module.ko, but I'd still like to be able to check the version of any arbitrary kernel module that's not necessarily going to be loaded by modprobe.