# System

Linux system tools, administration and tips

# ArchLinux Upgrade Issues

## Error: key "ABCDE1282828181" could not be looked up remotely

Upgrade archlinux-keyring: `pacman -S archlinux-keyring`

## Unable to get past login window after upgrading

This is caused by Nvidia driver being upgraded

nvidia-dkms: `pacman -S nvidia-libgl`

## Failed to start load kernel modules after upgrade:

Possible causes:

- `broadcom-wl` module
- Solved by re-"makepkg" `broadcom-wl` from **AUR**
- Find error message in `systemctl status systemd-modules-load.service`

# CentOS Installation Issues

## HP Microserver Gen 7

### Kernel Panic on Boot (Both Live USB and New Installation)

Add the following lines to the kernel boot parameters: `<span class="pln">nolapic clocksource</span><span class="pun">=</span><span class="pln">hpet</span>`

## <span class="pln">Blank Screen on Startup</span>

Append `nomodeset` to [kernel param](https://wiki.archlinux.org/index.php/kernel_parameters#GRUB "kernel param")

# Changing Default S2RAM to USWSUSP Suspend Module

If you have any issues to suspend your laptop e.g. `suspend` command doesn't work on your laptop, try changing the default sleep module to `uswsusp`:

1. Edit `/etc/pm/config.d/module` and add the following line: `SLEEP_MODULE=uswsusp`
2. Edit `/etc/pm/config.d/defaults` and add the following line: `S2RAM_OPTS="-f"`
3. Reboot and try to let her sleep.

### References

- [OpenSuse Documentation on Suspending](http://en.opensuse.org/SDB:Suspend_to_RAM)
- [AskUbuntu Thread](http://askubuntu.com/questions/54591/use-s2ram-when-closing-lid-with-kde)

# Fixing Incorrect Lid State by Hacking DSDT

When I install a Linux distro to my VAIO notebook, I found that there is an annoying bug with the lid switch. It does not get updated whenever I suspend on lid close, it means `cat /proc/acpi/button/lid/LID/state` will output `state: close`. When I close the lid again, it won't suspend, instead, it will change the state to open. So in order for it to suspend again on lid close after the first suspend, I have to close it, reopen the lid and close it again.

I have tried installing Linux Mint, Fedora, Fuduntu and Xubuntu, but it is not fixed in any of the distros. So, I don't think it is distro problems. While researching this issues (which I spent two full days), I found that Linux got an amazing feature that enable users to dynamically loading DSDT at boot time, there is no need to update the BIOS. So here's the instuctions:

1. Install `iasl` using `yum`, `apt-get` or whatever package management you are using.

2. Extract DSDT:
  ```
  $ sudo cat/sys/firmware/acpi/tables/DSDT > dsdt.aml
  ```

3. Disassemble `dsdt.aml` using the following command, this should create a new file `dsdt.dsl`:
  ```
  $ iasl -d dsdt.aml
  ```

4. Compile it using:
  ```
  $ iasl -tc dsdt.dsl
  ```

5. Fix any compiler errors, warnings and remarks. On my machine, the output is:
  ```
  dsdt.dsl  1352:                         And (CTRL, 0x1E)
  Warning  1106 -                                 ^ Result is not used, operator has no effect

  dsdt.dsl  1584:                     0x00000000,         // Length
  Error    4122 -                              ^ Invalid combination of Length and Min/Max fixed flags

  dsdt.dsl  2443:                                 Name (_T_0, 0x00)
  Remark   5111 -            Use of compiler reserved name ^  (_T_0)

  dsdt.dsl  2521:                                 Name (_T_0, 0x00)
  Remark   5111 -            Use of compiler reserved name ^  (_T_0)

  ```
  a. The first one is on line 1352 can be fixed simply by changing `And (CTRL, 0x1E)` to `And (CTRL, 0x1E, CTRL)`.  
  b. The second one is on line 1584, the length should be `Range Maximum` - `Range Minimum` + 1, on my machine, so fire up a hex calculator and start subtracting. On my machine, it's `0xE0000000` (`0xDFFFFFFF` - `0x00000000` + `0x00000001`).  
  c. The third and fourth line is on line 2443 and 2521, because it uses a reserved name, simply replacing all instances of `_T_0` to `T_0` will stop the complaints. In vim, it is as simple as issuing `:%s/_T_0/T_0/g` in command mode.

6. Once everything is fixed (no errors, warning or remarks), add the following line to `_WAK` method, simply search for `_WAK` in `dsdt.dsl`:
  ```
  If (LNotEqual (0x00, LIDS))
  {
  Store (0x00, LIDS)
  Notify (\_SB.LID, 0x80)
  }
  ```
  **NOTE 1:** You might need to change `\_SB.LID` to match your path to `LID` method or on some machine `LID0`. Method name is preceded by an `_` (underscore), so you can search for `_LID` in `dsdt.dsl`. After you found it, you have to determine the scope, scroll up until you found `Scope` keyword that your `LID` or `LID0` method belongs to, inside the bracket is the scope name. It may be in more than one scope, so, it might be `\_PCI0.SB.LID`. If you specify an incorrect path to `LID` method, you will receive the following error:
```
dsdt.dsl 300: Notify (LID, 0x80)
Error 4068 - ^ Object is not accessible from this scope (LID_)
```
  **NOTE 2:** What this function does is just to update the lid state once it is resumed from sleep. According to the ACPICA documentation, `_WAK` method is called by `AcpiLeaveSleepState()` function of ACPI. If the lid is open, the `LIDS` variable is `0x00`, or `0x01` otherwise. So these few lines translate to "if lid state is not open (closed), change lid state to open and call `LID`method".
7. Compile it using `iasl -tc dsdt.dsl`.
8. If no errors, warnings or remarks, add the following lines to `/etc/grub.d/01_acpi`:
  ```
  # Uncomment to load custom ACPI table
  GRUB_CUSTOM_ACPI="/boot/dsdt.aml"

  # DON'T MODIFY ANYTHING BELOW THIS LINE!

  prefix=/usr
  exec_prefix=${prefix}
  libdir=${exec_prefix}/lib

  . /usr/share/grub/grub-mkconfig_lib
  #. ${libdir}/grub/grub-mkconfig_lib

  # Load custom ACPI table
  if [ x${GRUB_CUSTOM_ACPI} != x ] && [ -f ${GRUB_CUSTOM_ACPI} ] \
      && is_path_readable_by_grub ${GRUB_CUSTOM_ACPI}; then
      echo "Found custom ACPI table: ${GRUB_CUSTOM_ACPI}" >&2
      prepare_grub_to_access_device `${grub_probe} --target=device 
  ${GRUB_CUSTOM_ACPI}` | sed -e "s/^/  /"
      cat << EOF
  acpi (\$root)`make_system_path_relative_to_its_root 
  ${GRUB_CUSTOM_ACPI}`
  EOF
  fi
  ```

9. Add executable bit to it:
  ```
  $ sudo chmod +x /etc/grub.d/01_acpi
  ```

10. Copy the new `dsdt.aml` to `/boot`:
  ```
  $ sudo cp dsdt.aml /boot
  ```

11. Regenerate `grub.cfg`:
  ```
  $ sudo grub2-mkconfig -o /boot/grub2/grub.cfg
  ```
12. Reboot

### References 
- [Archwiki on DSDT](https://wiki.archlinux.org/index.php/DSDT)
- [Redhat's Bug Report](https://bugzilla.redhat.com/show_bug.cgi?id=676031)
- [Ubuntu's Bug Report 1](https://bugs.launchpad.net/ubuntu/+source/linux/+bug/34389)
- [Ubuntu's Bug Report 2](https://bugs.launchpad.net/ubuntu/+source/linux/+bug/44825)
- [Somebody's blog on fixing DSDT errors, remarks and warnings](http://sadevil.org/blog/2012/01/01/fixing-the-acpi-dsdt-of-an-acer-ferrari-one-200/)
- [ACPICA Documentation](https://www.acpica.org/documentation)

# JournalD Administration

## Optimizing JournalD Disk Space Usage

Edit `/etc/systemd/journald.conf` and change the following line:

```
SystemMaxUse=200M 
```

To check disk space used by journald: `journalctl --disk-usage`

# Linux on Macbook Administration

## Blessing the Linux Kernel

1. [Boot into Mac Recovery](https://support.apple.com/en-us/HT201314 "Boot into Mac Recovery")
2. Start terminal and enter:
3. ```
    bless --folder /Volumes/ARCH_EFI/EFI/arch/grub/ --file /Volumes/ARCH_EFI/EFI/arch/grub/grubx64.efi
    ```

## Changing Apple keyboards (Macbook or USB) fnmode in Linux

### Changing it temporarily, as root:

```
echo 2 > /sys/module/hid_apple/parameters/fnmode 
```

### Changing it Permanently:

Edit `/etc/modprobe.d/hid_apple.conf` and add the following line:

```
options hid_apple fnmode=2 
```

# SELinux - Services Blocked by SELinux

## SELinux Blocked Apache Access to Files

```
setsebool -P httpd_unified 1<br></br>sudo /sbin/restorecon -R /var/www/html
```

## VSFTPD OOPS Error

Issue the following command: `setsebool -P ftp_home_dir 1`

## SSH bind port error permission denied

Issue the following command: `semanage port –a –t ssh_port_t –p tcp 1234`

## Permission denied HTTP Error 403

Issue the following command: `chcon -R --reference=/var/www /path/to/webroot`

## SELinux Denied HTTPD Access to MYSQLD on 127.0.0.1

1. `grep mysqld /var/log/audit/audit.log | audit2allow -M mysqld`
2. `semodule -i mysqld.pp`

## SELinux Denied FTP Access to SMB Share

1. Try to login with [ncftp](http://www.ncftp.com/ "ncftp") first and you will see the error "`OOPS: cannot change directory: /path/to/samba_share`"
2. Execute command: `su -c "grep ftpd_t /var/log/audit/audit.log | allow2audit -M ftpd_smb && semodule -i ftpd_smb"`
3. Try to login again with [ncftp](http://www.ncftp.com/ "ncftp") and ls command will return empty list a although it isn't
4. Execute command: `su -c "grep ftpd_t /var/log/audit/audit.log | allow2audit -M ftpd_smb && semodule -i ftpd_smb"`
5. Execute command =&gt; `sudo setsebool -P allow_ftpd_full_access on`
6. Execute command =&gt; `sudo setsebool -P ftp_home_dir on`

## Owncloud Custom Data Directory Denied

Assume owncloud data directory: `/var/data`

```
Install policycoreutils-python<br></br>/etc/init.d/restorecond start<br></br>chkconfig restorecond on<br></br>semanage fcontext -a -t httpd_sys_content_t '/var/data(/.*)?' <br></br>restorecon -Rv /var/data
```

# Standard CentOS Workstation Setup

### Install GUI (MATE Desktop)

1. `<span class="pln">sudo yum install epel</span><span class="pun">-</span><span class="pln">release</span>`
2. `<span class="pln">sudo yum groupinstall </span><span class="str">'X Window System'</span>`
3. `<span class="pln">sudo yum groupinstall </span><span class="str">'MATE Desktop'</span>`
4. `<span class="pln">sudo systemctl isolate graphical</span><span class="pun">.</span><span class="pln">target</span>`
5. `<span class="pln">sudo systemctl </span><span class="kwd">set</span><span class="pun">-</span><span class="kwd">default</span><span class="pln"> graphical</span><span class="pun">.</span><span class="pln">target</span>`

### Install Printer

1. `<span class="pln">sudo yum install cups</span>`
2. `<span class="pln">sudo yum groupinstall </span><span class="str">"Development Tools"</span>`
3. `<span class="pln">sudo systemctl enable cups</span>`
4. `<span class="pln">sudo systemctl start cups</span>`
5. `<span class="pln">sudo yum install foomatic</span>`

Install drivers for the printer available at [Open Printing](http://www.openprinting.org/printers)

### Optional - GUI WiFi Support

1. `<span class="pln">sudo yum install </span><span class="typ">NetworkManager</span><span class="pun">-</span><span class="pln">wifi</span>`