There are DDR4 interposers you can buy for 50$. The basic thing is that you don't need all of the ram all of the time, you just need to find an address which you can then rewrite to make two valid references to the same physical memory (see: badRAM/battering ram). Then you can use an IOMMU compliant DMA to access that memory.
Or you can use an FPGA to interpose the RAM and intercept the network traffic for a couple hundred bucks.
Indeed, you can buy a piece of fiberglass shaped correctly for 50$. That's not the hard part. Just the probe you are supposed to connect to such a PCB is > 1k USD per pin you need to sample. The oscilloscope / logic analyzer to sample it is likely 6-7 figures.
> Or you can use an FPGA to interpose the RAM and intercept the network traffic for a couple hundred bucks.
What FPGA solution do you have for a couple hundred bucks could interpose DDR4 RAM at any frequency? This number seems completely made up to me.
I do think a large portion of the huge price for this equipment is that it is very niche and only a few mfg's eg keysight/agilent make this kind of stuff.
Im sure if the DMA market goes way of the RAM bus sniffing its will be a year or two before mass produced products are on the market that can sniff the traffic without much reduction in signal quality and maximum data rate.
Or you can use an FPGA to interpose the RAM and intercept the network traffic for a couple hundred bucks.