added verbose mode

[c03rad0r]

Added verbose mode:

 sudo ./zycast -v -i enp53s0 -t 20 -f openwrt-24.10.5-ramips-mt7621-zyxel_nr7101-initramfs-recovery.bin
[sudo] password for c03rad0r: 
[2026-03-04 15:47:35] binding to interface 'enp53s0'
[2026-03-04 15:47:35] setting interpacket delay to 20 ms
[2026-03-04 15:47:35] mapping 'openwrt-24.10.5-ramips-mt7621-zyxel_nr7101-initramfs-recovery.bin' (len=7148738)
Press Ctrl+C to stop before rebooting target after upgrade
[2026-03-04 15:47:35] starting broadcast of image type 0x04 (len=7148738)
[2026-03-04 15:49:56] finished broadcast of image type 0x04
[2026-03-04 15:49:56] starting broadcast of image type 0x04 (len=7148738)

Verbose mode helps me to see what zycast is currently doing. However, unfortunately it didn't suffice to interrupt normal boot on my Zyxel NR7101:

$ sudo tio /dev/ttyUSB0 -b 57600
... ...
... ...
... ...
[15:47:06.990] Disconnected
[15:47:07.991] Warning: Could not open tty device (No such file or directory)
[15:47:07.991] Waiting for tty device..
[15:47:12.996] Connected

===================================================================
                MT7621   stage1 code 10:33:11 (ASIC)
                CPU=50000000 HZ BUS=16666666 HZ
==================================================================
Change MPLL source from XTAL to CR...
do MEMPLL setting..
MEMPLL Config : 0x11100000
3PLL mode + External loopback
=== XTAL-40Mhz === DDR-1200Mhz ===
PLL2 FB_DL: 0x10, 1/0 = 544/480 41000000
PLL4 FB_DL: 0x10, 1/0 = 516/508 41000000
PLL3 FB_DL: 0x13, 1/0 = 535/489 4D000000
do DDR setting..[00320381]
Apply DDR3 Setting...(use customer AC)
... ...
... ...
... ...
 NetLoop,call eth_halt ! 

 NetLoop,call eth_init ! 
Trying Eth0 (10/100-M)

 Waitting for RX_DMA_BUSY status Start... done


 ETH_STATE_ACTIVE!! 
Multiboot Listening...
 0
## Booting image at bc14017c ...
   Image Name:   OpenWrt Linux-3.10.14
   Image Type:   MIPS Linux Kernel Image (lzma compressed)
   Data Size:    14707522 Bytes = 14 MB
   Load Address: 80001000
   Entry Point:  80001000

@bmork any ideas what the issue could be with my NR7101 setup?

[bmork]

There are only two possible explanations (or three, if we consider an altered boot loader possible):

1. the NR7101 doesn't receive any multicast packets within the "Multiboot Listening..." window, or
2. the NR7101 doesn't like the received packets

Unfortunately there is no debug output from the NR7101 bootloader in either case. It silently assumes that missing packets or unrecognised packets is OK. Which it is of course.

I would snoop on the interface you are sending this to, verifying that the packets are going out as expected and that they look "reasonable". You could also look at packet counters and link LEDs to verify that there is traffic in the critical window.