# add to .bashrc for cli util
# e.g. `goblin netplan`
goblin() {
  local f
  f=$(curl -sL https://goblinlord.com)

  if [ -z "$1" ]; then
    echo "$f"
    return
  fi

  echo "$f" | awk -v term="$1" '
    BEGIN { IGNORECASE = 1; in_block = 0 }
    /^#/ {
      if (tolower($0) ~ tolower(term)) {
        in_block = 1
        print $0
        next
      }
      if (in_block) {
        print ""
        in_block = 0
      }
      next
    }
    {
      if (in_block) print
    }
  '
}


# Serial Console over GRUB on Ubuntu
echo 'GRUB_CMDLINE_LINUX="console=tty0 console=ttyS0,115200n8"' >> /etc/default/grub
update-grub

# Remove Netplan and add systemd-networkd
apt remove -y netplan.io
rm /etc/netplan/ /usr/share/netplan/ -r
systemctl enable systemd-networkd

-Optional: create systemd network file:
cat > /etc/systemd/network/00-wired.network << EOF
[Match]
Name=e*

[Network]
DHCP=yes
EOF

-then reboot


# TCPDump pipe to Wireshark over SSH jump
ssh -J user@jump user@target 'sudo tcpdump -i eth0 -U -w -' | wireshark -k -i -

# Find and kill process by port
lsof -i :8080
kill -9 $(lsof -t -i :8080)

# Get public IP quietly
curl -s ifconfig.me

# Write ISO to USB (double check /dev/sdX with lsblk)
sudo dd if=linux.iso of=/dev/sdX bs=4M status=progress oflag=sync

# Reverse SSH tunnel to reach a machine behind NAT
- establish from hidden host:
ssh publicbox -R7777:local-ssh-able-host:22

- then from help:
ssh -J publicbox -p 7777 user@local-ssh-able-host


# Grant raw socket capability to tcpdump binary (all users)
sudo setcap cap_net_raw,cap_net_admin=eip /usr/sbin/tcpdump

- Optional: restrict by group
sudo chgrp netmon /usr/sbin/tcpdump
sudo chmod 750 /usr/sbin/tcpdump
sudo usermod -aG netmon youruser