Netcat weirdness - 72 byte errors

I thought I'd take a closer look at what was happening with my netcat problem.

I ran a cmp on the files to see just what was happening.

cmp -l /media/sdk1/BACKUP_2018_01_15_BY_USB /media/sdk1/BACKUP_2018_01_15_BY_NETWORK
 10056230615   5   0
 10056230616 152  25
 10056230617 264 351
 10056230618 151  57
 10056230619  14 205
 10056230620 357 125
 10056230621 156   0
 10056230622 326  32
...

(Oh and if those "bytes" look weird, cmp outputs the bytes in octal...go figure. cmp prints the byte offset in decimal and the byte itself in octal)


and what's weird is that the error blocks are 72 bytes in length. (I think that's the length of an ethernet frame)

and even more strange is that the error blocks are always the same exact data. Above you can see the sequence 0,25,351,57 etc...
That's the same 72 byte sequence in each error block.

I loaded the output into LibreOffice Calc and graphed it:

So out of 250GB of data, there are around 432 bytes different, 6 blocks of 72 (72*6=432).



Column H and I are just =CHAR(OCT2DEC(B1)) and = CHAR(OCT2DEC(C1)) copied downward.




I actually did the copy over the network twice and got different results:



(edit: I thought it was a realtek 8169 but it's actually a Marvell Yukon)

The sending network card is a Marvell Yukon (D-Link DGE-530T) using the skge driver running under Knoppix 8.1.

dmesg | grep eth
[   19.502067] skge 0000:02:07.0 eth0: addr 00:15:e9:2f:85:55
[   58.971634] skge 0000:02:07.0 eth0: enabling interface
[   61.389533] skge 0000:02:07.0 eth0: Link is up at 1000 Mbps, full duplex, flow control both

 dmesg | grep skge
[   19.501793] skge: 1.14 addr 0xfe1fc000 irq 16 chip Yukon-Lite rev 9
[   19.502067] skge 0000:02:07.0 eth0: addr 00:15:e9:2f:85:55
[   58.971634] skge 0000:02:07.0 eth0: enabling interface
[   61.389533] skge 0000:02:07.0 eth0: Link is up at 1000 Mbps, full duplex, flow control both

lspci -vv

02:07.0 Ethernet controller: D-Link System Inc Gigabit Ethernet Adapter (rev 11)
 Subsystem: D-Link System Inc DGE-530T Gigabit Ethernet Adapter
 Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV+ VGASnoop- ParErr- Stepping- SERR+ FastB2B- DisINTx-
 Status: Cap+ 66MHz+ UDF- FastB2B+ ParErr- DEVSEL=medium >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
 Latency: 64 (5750ns min, 7750ns max), Cache Line Size: 64 bytes
 Interrupt: pin A routed to IRQ 16
 Region 0: Memory at fe1fc000 (32-bit, non-prefetchable) [size=16K]
 Region 1: I/O ports at ec00 [size=256]
 Expansion ROM at fe200000 [disabled] [size=128K]
 Capabilities: [48] Power Management version 2
  Flags: PMEClk- DSI- D1+ D2+ AuxCurrent=0mA PME(D0+,D1+,D2+,D3hot+,D3cold+)
  Status: D0 NoSoftRst- PME-Enable- DSel=7 DScale=1 PME-
 Capabilities: [50] Vital Product Data
  Product Name: DGE-530T Gigabit Ethernet Adapter
  Read-only fields:
   [PN] Part number: DGE-530T
   [EC] Engineering changes: Rev. 1.1
   [MN] Manufacture ID: 44 2d 4c 69 6e 6b 20 43 6f 72 70 2e
   [SN] Serial number: DGE530T2F8555
   [CP] Extended capability: 01 10 cc 03
   [RV] Reserved: checksum good, 25 byte(s) reserved
  Read/write fields:
   [RW] Read-write area: 121 byte(s) free
  End
 Kernel driver in use: skge
 Kernel modules: skge

lspci
00:00.0 Host bridge: Intel Corporation 82850 850 (Tehama) Chipset Host Bridge (MCH) (rev 04)
00:01.0 PCI bridge: Intel Corporation 82850 850 (Tehama) Chipset AGP Bridge (rev 04)
00:1e.0 PCI bridge: Intel Corporation 82801 PCI Bridge (rev 04)
00:1f.0 ISA bridge: Intel Corporation 82801BA ISA Bridge (LPC) (rev 04)
00:1f.1 IDE interface: Intel Corporation 82801BA IDE U100 Controller (rev 04)
00:1f.2 USB controller: Intel Corporation 82801BA/BAM UHCI USB 1.1 Controller #1 (rev 04)
00:1f.3 SMBus: Intel Corporation 82801BA/BAM SMBus Controller (rev 04)
00:1f.4 USB controller: Intel Corporation 82801BA/BAM UHCI USB 1.1 Controller #2 (rev 04)
01:00.0 VGA compatible controller: NVIDIA Corporation NV44A [GeForce 6200] (rev a1)
02:07.0 Ethernet controller: D-Link System Inc Gigabit Ethernet Adapter (rev 11)
02:08.0 USB controller: NEC Corporation OHCI USB Controller (rev 43)
02:08.1 USB controller: NEC Corporation OHCI USB Controller (rev 43)
02:08.2 USB controller: NEC Corporation uPD72010x USB 2.0 Controller (rev 04)
02:09.0 Multimedia audio controller: Creative Labs EMU10k1X [SB Live! Value/OEM Series]
02:09.1 Input device controller: Creative Labs [SB Live! Value] Input device controller
02:0a.0 USB controller: NEC Corporation OHCI USB Controller (rev 41)
02:0a.1 USB controller: NEC Corporation OHCI USB Controller (rev 41)
02:0a.2 USB controller: NEC Corporation uPD72010x USB 2.0 Controller (rev 02)

lsb_release -a
No LSB modules are available.
Distributor ID: Debian
Description:    Debian GNU/Linux 9.1 (stretch)
Release:        9.1
Codename:       stretch

cat /mnt-system/KNOPPIX/kversion
8.1-2017-09-05