Extension by Raf

payloads/extensions/get2_dhclient.sh

@@ -0,0 +1,59 @@
+#!/bin/bash
+
+# get2_dhclient.sh - Bash Bunny extension to change from a DHCP server to a client.
+# This is needed when connected to macOS/OSX with Internet Sharing because
+# the host is the DHCP server and the Bash Bunny is the DHCP client.
+#
+# It also replaces the standard GET function so that TARGET_IP, TARGET_HOSTNAME
+# and HOST_IP work properly without having to modify the standard version. It
+# renames and uses the standard version for any other environment variables.
+#
+# Note that this must be sourced after get.sh so it is named "get2_dhclient.sh"
+# on the assumption that they are sourced in order by filename.
+#
+# This is free software released under the terms of the GPLv2+
+#
+# 20190321 raf <raf@raf.org>
+
+function DHCLIENT() {
+
+	# Do nothing if GET isn't defined (get.sh hasn't been sourced yet)
+	[ $(declare -f GET | /usr/bin/wc -l) = 0 ] && return
+
+	# Do nothing if we've already done it
+	[ $(declare -f orig_GET | /usr/bin/wc -l) != 0 ] && return
+
+	# Stop the DHCP server if it is running
+	/bin/systemctl status isc-dhcp-server && /bin/systemctl stop isc-dhcp-server
+
+	# Bring down the usb0 network interface
+	/sbin/ifdown usb0
+
+	# Bring it up again as a DHCP client
+	/sbin/dhclient usb0
+
+	# Rename the standard GET function before we replace it
+	eval "$(echo "orig_GET()"; declare -f GET | tail -n +2)"
+	export -f orig_GET
+
+	# Replace GET so that TARGET_IP, TARGET_HOSTNAME and HOST_IP work
+	function GET() {
+		case "$1" in
+			"TARGET_IP")
+				export TARGET_IP=$(awk '/option routers/ { tip = substr($3, 1, length($3)-1) } END { print tip }' /var/lib/dhcp/dhclient.leases)
+				;;
+			"TARGET_HOSTNAME")
+				export TARGET_HOSTNAME=$(awk '/server-name/ { thn = substr($2, 2, length($2)-3) } END { print thn }' /var/lib/dhcp/dhclient.leases)
+				;;
+			"HOST_IP")
+				export HOST_IP=$(awk '/fixed-address/ { hip = substr($2, 1, length($2)-1) } END { print hip }' /var/lib/dhcp/dhclient.leases)
+				;;
+			*)
+				orig_GET "$1"
+				;;
+		esac
+	}
+}
+
+export -f DHCLIENT
+