Recover information when pfsense router doesn’t boot

In this entry I’m going to explain how I could recover information from my router (APU1D4) when router doesn’t boot. Since a couple of days I get this error message booting device:
elf64_loadimage: failed to read section headers

I have to say that I had installed pfSense 2.4.2-RELEASE on my router, this distribution is based on FreeBSD, and after some time investigating I couldn’t find the problem so I decided to get all useful data from my router (I had an internal Git repo running there) and reinstall it.

To access to router internal drive I installed a new pfSense version to write in a memory stick:

$ gunzip -c pfSense-CE-memstick-serial-2.4.4-RELEASE-p3-amd64.img.gz | sudo dd of=/dev/sdc bs=1M

Check USB stick:

$ fdisk -l /dev/sdc
 Disk /dev/sdc: 15 GiB, 16122904576 bytes, 31490048 sectors
 Units: sectors of 1 * 512 = 512 bytes
 Sector size (logical/physical): 512 bytes / 512 bytes
 I/O size (minimum/optimal): 512 bytes / 512 bytes
 Disklabel type: dos
 Disk identifier: 0x90909090 
Device     Boot   Start     End Sectors   Size Id Type
 /dev/sdc1             1    1600    1600   800K ef EFI (FAT-12/16/32)
 /dev/sdc2  *       1601 1477200 1475600 720.5M a5 FreeBSD
 /dev/sdc3       1477201 1550928   73728    36M  b W95 FAT32

Plug USB memstick in my router and press F10 while is booting to select boot device:

Press F10 key now for boot menu:
Select boot device: 
1. USB MSC Drive UFD 3.0 Silicon-Power16G 1100
2. AHCI/0: TS32GMSA370 ATA-9 Hard-Disk (30533 MiBytes)
3. Payload [setup]
4. Payload [memtest]
Select boot device: 1

Then follow all steps needed I can select the following option:
Rescue Shell > Launch a shell for rescue operations

Once I’m in rescue shell I need to mount my internal drive to copy my internal repository to an external computer in my LAN, but I need to find which the device name and partition is used by my old pfsense installation using these commands:

# geom disk list
Geom name: ada0
Providers:
1. Name: ada0
    Mediasize: 32017047552 (30G)
    Sectorsize: 512
    Mode: r0w0e0
    descr: TS32GMSA370
    ident: D007501916
    rotationrate: 0
    fwsectors: 63
    fwheads: 16
...

Device name found and now:

# gpart show -p
=>      63  62533233    ada0  MBR  (30G)
         63  62533233  ada0s1  freebsd  [active]  (30G) 
=>       0  62533233   ada0s1  BSD  (30G)
          0        16           - free -  (8.0K)
         16  45756001  ada0s1a  freebsd-ufs  (22G)
   45756017  16777216  ada0s1b  freebsd-swap  (8.0G)

With partition name I can mount what I need:

 # mount /dev/ada0s1a /mnt

At this point is needed to setup network interface to communicate with LAN using ifconfig command:

# ifconfig re0 192.168.1.XXX netmask 255.255.255.0 broadcast 192.168.1.255 up

And then we can copy all information that I need so I’m able to reinstall my router safetely.

It would be great to discover the root cause because FreeBSD kernel couldn’t read section headers but at least I didn’t loose any information.

Quite simple procedure but it was the first time I had to use a rescue shell in pfsense.

That’s all folks!!

—
“Well done is better than well said.”
— Benjamin Franklin