If a QCow2 image is strictly required (e.g., for a custom QEMU implementation of a router), the binary must be extracted, and a new disk image must be built.
Step 1: Analyze the Binary
Use binwalk to find the embedded kernel and filesystem.
binwalk cisco_image.bin
Output will show offsets for the kernel and compressed filesystems (squashfs/jffs2).
Step 2: Extract the Contents Extract the filesystem from the binary.
binwalk -e cisco_image.bin
This creates a folder (usually _cisco_image.bin.extracted) containing the root filesystem of the router.
Step 3: Create a Raw Disk Image Create a convert cisco bin to qcow2
Converting a Cisco .bin file to .qcow2 isn't a direct "save as" process because .bin files are compressed firmware for physical hardware, while .qcow2 is a virtual disk format. To bridge this gap, you usually need to uncompress the image first or use a tool like qemu-img if the source is already a virtual disk like .vmdk. The Conversion Breakdown
Depending on your image type, follow the relevant path below: 1. For Standard IOS (Dynamips) Images
If you have a classic router image (e.g., c3745-adv.bin), these are typically compressed archives that need to be "unzipped" rather than converted into a virtual disk.
Step 1: Upload the .bin to your Linux environment (like EVE-NG or GNS3).
Step 2: Use the unzip command to extract it:unzip -p c3745-adventerprisek9-mz.124-15.T7.bin > c3745.image. Step 3: Use this .image file directly in your emulator. 2. For Virtual Images (IOSv, ASAv, NX-OS) If a QCow2 image is strictly required (e
If you are starting with a VMware-style .vmdk or an .ova (which contains a .vmdk), you can use the QEMU disk image utility to convert it to .qcow2. Cisco Modeling Lab IOS Image convert
Converting a Cisco is a common request for running Cisco images in virtual environments like Cisco Modeling Labs (CML) Feature: Automated Cisco Image Converter
: Simplify the manual and often error-prone process of preparing Cisco hardware-based binary images for cloud-native and virtualized network labs. 1. Core Workflow
The feature should automate the following multi-step manual process: : Upload the source (Cisco IOS) or (IOS-XE) file. Uncompression
: Automatically unpack the binary to extract the raw kernel/image file. Format Transformation to convert the extracted file into the Optimization : Run a consistency check ( qemu-img check ) and compress the output to save disk space. Cisco Community 2. Technical Specifications Conversion Engine : Integrated QEMU disk image utility Supported Source Formats Validation Layer Output will show offsets for the kernel and
: A metadata check to ensure the hardware architecture (e.g., Cat9k vs. CSR1000v) is compatible with the target x86 hypervisor. Cisco Community 3. Integration with Lab Managers
The converted image should be ready for immediate deployment through: Cisco Modeling Lab IOS Image convert
| Cisco Platform | QCOW2 Conversion Support | Notes |
|----------------|--------------------------|-------|
| CSR1000v (IOS-XE) | ✅ Full | Boot via kernel or bootloader |
| ASAv (ASA on KVM) | ✅ Full | Requires specific OVA → qcow2 extraction |
| vIOS / vIOS-L2 | ✅ Native | Already qcow2 in VIRL/CML packages |
| IOS (7200, 3725) | ⚠️ Partial | Better as -kernel boot, not disk-based |
| NX-OS (Titanium) | ❌ Not supported | Uses different boot architecture |
This method preserves the .bin as a kernel, using .qcow2 only for configuration storage.
qemu-img create -f qcow2 cisco-flash.qcow2 16M
qemu-system-x86_64 \
-machine pc \
-cpu host \
-m 512 \
-kernel c7200-advsecurityk9-mz.152-4.S6.bin \
-append "console=ttyS0" \ # Redirect console to serial
-drive file=cisco-flash.qcow2,if=ide,format=qcow2 \
-serial stdio \
-netdev user,id=net0 -device e1000,netdev=net0
Why this sometimes works: Some Cisco IOS-XE images (especially for CSR1000v) contain a Linux kernel that understands the -kernel boot protocol. Older IOS .bin will not boot this way. You will likely see:
Loading: ....
Entry point: 0x80001000
Error: Unsupported boot type