安全与隐私stdw.github.io
我逆向工程了有线调制解调器，把它变成 SDR
Show HN: I reverse engineered my cable modem and turned it into an SDR
2020 — 2024，它一次次回到首页
黑点是上首页（≥ 50 分）的那次投稿，空心点是没冲上去的投稿，点越大分数越高。
导读
作者逆向工程了自己的有线调制解调器（cable modem），通过硬件手段绕过厂商限制，把调制解调器内置的调谐芯片改造成软件定义无线电（SDR）来接收射频信号。文章详细记录了从拆解、焊接、固件分析到最终实现 SDR 的全过程。
为什么经久不衰：它展示了普通消费设备中隐藏的硬件潜力，是硬件逆向工程领域的经典案例，多年后仍是学习 SDR 和硬件 hack 的绝佳参考。
HN 评论精选
分享多种实用的芯片引脚改造焊接技巧
如果焊接 SOIC 芯片时把引脚弄断了也别慌，通常可以磨掉一点塑料封装，露出足够的引脚金属来焊一根飞线到 VCC。另一种方法是沿着 VCC 走线切断，再自己焊线接到附近的电容并加个开关。注意走线可能还连着其他芯片，但这通常没问题，有时反而是好事，因为上拉电阻仍能供电。还有一个办法是在四个引脚上堆一团焊锡，全部加热后把半边芯片撬起来，另外四条腿会又热又软，容易弯折。对于非 VCC 的连接，也可以顺着走线找更容易焊接的位置，而不是并排的一堆引脚。
Scoundreller查看英文原文
> I chose to overcome this by heating the VCC pin with my soldering iron and very carefully lifting it off the pad. This is a convenient, but rather crude solution which may result in snapped off leads so use at your own risk! If that mishap on an SOIC chip occurs, don’t fret, you can usually shave off a bit of the plastic and get enough pin surface to solder a jumper to VCC. An alternate method is to follow the VCC trace and cut it, then solder your own wire to the unlifted lead and a nearby capacitor with a switch. Beware that you might power more than the chip if the trace continues, but that’s usually fine. Sometimes this is a good thing because you still power pull-up resistors. Yet another option is to place a glob of solder across 4 pins, heat them all up, and lift half the chip. The other 4 legs will be hot and soft enough to bend easily. Finally for the non-VCC connections, could follow the traces and find easier places to solder to rather than a bunch of side-by-side leads.
惊讶于固件为调试接口预留的 2 秒启动延迟影响了所有设备
等等，数以亿计的有线调制解调器每次启动都要延迟 2 秒，就为了防止有人焊了串口想加载不同的固件镜像？
Scoundreller查看英文原文
> Found image 1 at offset 20000 > Enter '1', '2', or 'p' within 2 seconds or take default... Wait, tens or hundreds of millions of cable modem startups are delayed by 2s on each start just in case somebody has soldered up a serial interface and wants to load a different image?
解释同轴电缆的射频本质及 MoCA 的安全原理
我最近才明白同轴电缆本质上就像 WiFi 一样的射频频谱，只不过是在电缆内部，但很难找到有人这样解释。我买过用同轴电缆在高频上跑以太网的 MoCA 设备（TiVo 和新机顶盒都用），一开始不理解'这怎么保证安全'——我的调制解调器也接在同一条同轴上，而且显然不在防火墙后面。后来才明白，当然是通过滤波把信号挡在电缆里不让外泄。我宁愿直接跑以太网放在防火墙后面，但这至少省得在墙上打洞了。
0xCMP查看英文原文
I only recently understood that my Coax cables are basically like an RF spectrum similar to Wifi except inside the cables. It appears this is taken as obvious because I had a really hard time finding someone explain it like that. I bought these boxes which use the Coax at very high frequencies to do Ethernet between sides of my house using MoCa which is used by TiVos and newer set top boxes. I had trouble understanding "how is this secure" when my modem is also connected to the same coax and this is clearly not behind my firewall. Well, of course, you filter out the signal from leaving through the Coax which provides you cable! I would rather just run ethernet and keep it behind a firewall, but this reduces punching holes in the walls for now.
称赞这是真正体现黑客精神的作品
非常出色的工作，真正配得上'Hacker' News 这个名号 =)
chromatin查看英文原文
Absolutely outstanding work, truly worthy of the moniker "hacker" news =)
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