Blog: Add old blog posts

blog/2019-03-10_new-site.md

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+# New Blog
+
+This is a new blog that will serve as my central hub for sharing ideas,
+tutorials, and thoughts.

blog/2019-03-11_introduction-to-qemu.md

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+# Introduction to QEMU for Hackers
+
+One of the things that I've noticed in the infosec community is the tendency to
+stick to the proprietary virtualization tools that are familiar.
+People often are quick discount tools that they don't already know, so I have
+written this blog post in an attempt to foster an interest in exploring other
+virtualization options.  My hope is that, even if you don't come away wanting to
+use QEMU in your CTF lab or malware analysis playpen, you will at least be more
+open to looking into other forms of emulation and virtualization.
+
+## The Case for QEMU
+Many hacking event organizers spend ample time pointing and clicking through
+their VirtualBox and VMware configuration wizards to setup their hacking labs.
+What if I told you there was a better way that works on Linux, macOS, Windows,
+and Xen?
+
+### Enter QEMU
+With [QEMU](https://www.qemu.org/) your VMs are defined as the arguments passed
+to QEMU on its invocation at the command line.  For example, you might invoke a
+VM as such (note that **`>`** is a
+[**$PS2** prompt](http://tldp.org/HOWTO/Bash-Prompt-HOWTO/x157.html)):
+```
+$ qemu-system-x86_64 -machine type=q35 --enable-kvm -cpu host -smp cpus=8 \
+> -m 512M -netdev user,id=net0 -device e1000,netdev=net0 -hda dsk/vm-hdd.qcow
+```
+
+### Shell Scripts as VM Templates
+
+Obviously this isn't a good long-term way to run your VM, but fear not, as there
+is a better way!  All you have to do is save your VM arguments to an executable
+shell script like the following:
+```
+#!/usr/bin/env bash
+
+# image creation command:
+# qemu-img create -f qcow2 -o preallocation=metadata dsk/vm-hdd.qcow 20G
+
+qemu-system-x86_64 \
+  -machine type=q35 \
+  --enable-kvm \
+  -cpu host \
+  -smp cpus=8 \
+  -m 512M
+  -netdev user,id=net0 \
+  -device e1000,netdev=net0 \
+  -hda dsk/vm-hdd.qcow \
+;
+```
+
+Don't forget to make your script executable!
+```
+$ chmod +x vm-foo
+```
+
+The nice thing about these scripts is that you can freely copy and edit them
+with the standard UNIX command-line tools that you are used to, meaning that
+you can use one VM script as a template for another virtual machine.  Making a
+VM based on a template then becomes as simple as copying a bash script:
+```
+$ cp vm-foo vm-bar
+```
+
+For more information on creating QEMU disk images, see the
+[qemu-img(1)](https://linux.die.net/man/1/qemu-img) man page.
+
+### QEMU's Advanced Features
+QEMU is a capable of emulating foreign CPU architectures, as well as working in
+conjunction with a hypervisor to perform fully-accelerated, near
+native-performance virtualization.  Some of the supported architectures for
+full-system emulation are:
+
+- Alpha
+- Altera Nios II
+- ARM
+- Axis ETRAX CRIS
+- HP PA-RISC
+- i386/x86
+- IBM System/390
+- Microblaze (big and little endian)
+- MIPS (big and little)
+- MIPS64 (big and little)
+- Motorola 68000
+- Moxie
+- OpenRISC 1k (IP core for FPGAs)
+- PowerPC
+- PowerPC 64 (big and little)
+- RISC V
+- RISC V 64
+- SuperH SH-4
+- SPARC and SPARC32 Plus
+- SPARC64
+- TILE-Gx
+- Xtensa
+
+Some of its other features include:
+
+- Support for the Intel HAXM, Linux KVM, and Xen hypervisors
+- PCIe passthrough
+- attaching physical disks to VMs
+- USB passthrough
+- network block devices
+- importing and converting disks from other formats
+- command-line interactive monitor
+- VNC support
+- multiple virtual VGA adapters and video modes
+- tap/tun support (bridging to actual network interfaces on the host)
+
+*Stay tuned for more!*

blog/2022-02-04_inkscape-eps.md

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+# Inkscape Postscript Export in 2022
+
+A lot of older guides using Inkscape to convert SVG images to PostScript
+use a `-E` CLI flag that no longer exists in the Inkscape CLI:
+~~`inkscape input.svg -E out.eps`~~.
+
+**The correct way to do this in the *current* year:**
+```
+inkscape --export-type=eps -o out.eps in.svg
+```
+
+If you want to automatically convert all of the `.svg` files in your current
+working directory to `.eps` files, you can use something like this script:
+```bash
+#!/usr/bin/env bash
+for svg in *.svg; do
+    bname=$(basename "$svg" | sed 's/\.svg$//g')
+    echo "Converting \""$bname"\"..."
+    echo -e "\tinkscape --export-type=eps -o \"$bname.eps\" \"$svg\""
+    inkscape --export-type=eps -o "$bname.eps" "$svg"
+done
+```

blog/2022-03-28_FFmpeg-Window-Capture.md

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+# FFmpeg Window Capture
+
+If you've read the FFmpeg website's
+[Capture/Desktop](https://trac.ffmpeg.org/wiki/Capture/Desktop) page
+or another similar tutorial about screen recording, you may have learned
+that the `x11grab` device can be used to capture a specific region of your
+screen, but did you know that you can also record a window by it's ID just
+like OBS does?
+
+First, you'll need to find the ID of the window that you want to capture
+with `xwininfo`:
+
+  <center>
+    <video height="100%" width="700vmin" autoplay loop>
+      <source src="/media/xwininfo.mp4" type="video/mp4" />
+    </video>
+  </center>
+
+Now we can use the `-window_id` parameter of the `x11grab` device with
+FFmpeg to capture the window.  Here's an example of a "nearly lossless"
+MP4 capture at 60 frames per second with a constant quality of `10`:
+```bash
+ffmpeg -f x11grab -thread_queue_size 4096 -framerate 60 -window_id 0x940000a \
+  -c:v libx264 -crf 10 output.mp4
+```
+
+### Recording With NVENC
+
+If you're using an NVIDIA card with proprietary drivers, you can encode with
+NVENC:
+```bash
+ffmpeg -f x11grab -thread_queue_size 4096 -framerate 60 -window_id 0x940000a \
+  -c:v hevc_nvenc -preset slow -tune hq -tier high -cq 10 output.mp4
+```
+
+## Recording Desktop Audio
+
+If you'd like to record desktop audio with Pulse or PipeWire, you can find
+the name of your audio card with `pactl` (line-wrapped to 80 columns):
+```
+$ pactl list short | grep monitor
+75      alsa_output.usb-Focusrite_Scarlett_2i2_USB_Y8QUZ0C9981932-00.analog-ster
+eo.monitor        PipeWire        s32le 2ch 48000Hz       RUNNING
+77      alsa_output.pci-0000_2d_00.1.hdmi-stereo-extra2.monitor PipeWi
+e        s32le 2ch 48000Hz RUNNING
+79      alsa_output.usb-C-Media_Electronics_Inc._USB_Multimedia_Audio_Device-00.
+analog-stereo.monitor     PipeWire        s16le 2ch 48000Hz       RUNNING
+81      alsa_output.pci-0000_2f_00.4.iec958-stereo.monitor      PipeWire        
+s32le 2ch 48000Hz RUNNING
+212     easyeffects_sink.monitor        PipeWire        float32le 2ch 48000Hz   
+RUNNING
+448     alsa_output.usb-SmartAction_FiiO_USB_Audio_Class_2.0_DAC_0007-00.analog-
+stereo.monitor    PipeWire        s32le 2ch 48000Hz       RUNNING
+858     soundux_sink.monitor    PipeWire        float32le 2ch 48000Hz   RUNNING
+```
+
+You can then record audio and video together with FFmpeg like so:
+```bash
+ffmpeg -f x11grab -thread_queue_size 4096 -framerate 60 -window_id 0x940000a \
+  -f pulse -thread_queue_size 8192 -ac 2 \
+  -i alsa_output.usb-SmartAction_FiiO_USB_Audio_Class_2.0_DAC_0007-00.analog-stereo.monitor \
+  -c:a aac -b:a 256k \
+  -c:v libx264 -crf 10 output.mp4
+```
+
+## Putting It All Together in a Script
+
+Below is a script that automates this somewhat.  Note that you will
+need to edit the `audio_device` variable for the `-a` flag to work.  You may
+also want to edit the `recording_dir` as well.
+```bash
+#!/usr/bin/env bash
+
+recording_dir='.'
+date=$(date +%Y-%m-%d_%s)
+show_cursor=0
+show_region=0
+record_audio=0
+use_nvenc=0
+prefix=""
+audio_device=''
+
+read -d '' usage <<EOF
+USAGE
+  window-capture [OPTIONS]
+
+OPTIONS
+  -h  Show this help.
+  -a  Capture audio.  Make sure you modify the "audio_device" in the script!
+  -n  Encode with NVENC.
+  -c  Capture X cursor (disabled by default).
+  -s  Show capture region.
+  -p  Filename prefix (override default from window title).
+  -d  Capture directory (override "$recording_dir").
+EOF
+
+chomp(){ sed 's/^\s\+//' | sed 's/\s\+$//' ; }
+
+while getopts ':hcsp:d:an' opt; do
+  case ${opt} in
+    h)
+      cat <<<"$usage"
+      exit 0
+      ;;
+    c)
+      show_cursor=1
+      ;;
+    s)
+      show_region=1
+      ;;
+    p)
+      prefix="$OPTARG"
+      ;;
+    d)
+      recording_dir="$OPTARG"
+      ;;
+    a)
+      [ -z "$audio_device" ] \
+        && echo 'ERROR: Set "audio_device" first!' \
+        && exit 1
+      record_audio=1
+      ;;
+    n)
+      use_nvenc=1
+      ;;
+    *)
+      cat <<<"$usage"
+      exit 1
+      ;;
+  esac
+done
+
+window_info=$(xwininfo)
+winid_line=$(grep '^xwininfo:\s\+[wW]indow\s\+[iI][dD]:\s\+' <<<"$window_info")
+window_id=$(awk '{print $4}' <<<"$winid_line")
+if [ -z "$prefix" ]; then
+  prefix=$( \
+    sed 's/^xwininfo:\s\+[wW]indow\s\+[iI][dD]:\s\+[0-9xXa-fA-F\]\+\s\+"\(.*\)"\s*$/\1/' \
+      <<<"$winid_line" \
+    | sed 's/\s/_/g' | sed 's/\~/home/g' | sed 's/\//-/g' | sed 's/@/_/g' | chomp)
+fi
+
+if [ $record_audio -eq 1 ]; then
+  audio_opts="-f pulse -thread_queue_size 8192 -ac 2 -i $audio_device -c:a aac -b:a 256k"
+else
+  audio_opts="-an"
+fi
+
+if [ $use_nvenc -eq 1 ]; then
+  enc_opts='-c:v hevc_nvenc -preset slow -tune hq -tier high -cq 10'
+else
+  enc_opts='-c:v libx265 -crf 10'
+fi
+
+ffmpeg \
+  -f x11grab -thread_queue_size 8192 -framerate 60 -window_id $window_id \
+  -show_region $show_region -draw_mouse $show_cursor -i :0.0 \
+  $audio_opts \
+  $enc_opts \
+  "$recording_dir/$prefix"_"$date.mkv" \
+;
+```
+
+[DOWNLOAD](/blob/window-capture)