Modifying the /etc/hosts file, a common technique for blocking or redirecting websites, can unexpectedly break the Substack editor. Specifically, redirecting fonts.googleapis.com to localhost, even with served font files, causes the editor to malfunction, preventing text entry. This issue seems tied to Substack's Content Security Policy (CSP), which restricts the sources from which the editor can load resources. While the author's workaround was to temporarily disable the redirect while using the editor, the underlying problem highlights the potential for conflicts between local system configurations and web applications with strict security policies.
The Substack editor, a web-based platform used for composing and publishing newsletters and other online content, exhibits unexpected and disruptive behavior when the local system's /etc/hosts file contains certain entries. Specifically, the author, Lee Robinson, discovered that adding a line mapping substack.com to 127.0.0.1, effectively redirecting any traffic intended for Substack's servers to the local machine (localhost), caused the editor to malfunction.
Robinson, a frequent Substack user, initially encountered this issue while attempting to troubleshoot a separate, unrelated network problem. Modifying the /etc/hosts file is a common debugging technique used to control network routing. However, in this instance, the seemingly innocuous addition inadvertently interfered with the Substack editor's functionality. The precise manifestation of the breakage wasn't explicitly detailed, but it was significant enough to disrupt Robinson's workflow and prompt investigation.
Through experimentation, Robinson determined that simply the presence of the substack.com entry in /etc/hosts, even if commented out (effectively deactivated), triggered the issue. This points towards a potential parsing or pre-flight check mechanism within the Substack editor that scans the /etc/hosts file, possibly for security or diagnostic purposes. This unexpected dependency on the local host's file system configuration creates an unusual interaction where modifications intended for local network management inadvertently affect a remote web application's behavior. The author concluded by suggesting Substack developers investigate this unexpected dependency to prevent future conflicts and improve the robustness of their editor.
Summary of Comments ( 321 )
https://news.ycombinator.com/item?id=43793526
Hacker News commenters discuss the Substack editor breaking when
/etc/hostsis modified to block certain domains. Several suggest this is due to Substack's reliance on third-party services for things like analytics and advertising, which the editor likely calls out to. Blocking these in/etc/hostslikely causes errors that the editor doesn't handle gracefully, thus breaking functionality. Some commenters find Substack's reliance on these external services concerning for privacy and performance, while others propose using browser extensions like uBlock Origin as a more targeted approach. One commenter notes that even local development can be affected by similar issues due to aggressive content security policies.The Hacker News post "Writing "/etc/hosts" breaks the Substack editor" has generated several comments discussing the original Substack article's claim that modifying the /etc/hosts file can interfere with the Substack editor.
Several commenters express skepticism about the article's core premise. One commenter suggests that the issue isn't directly related to modifying /etc/hosts itself, but rather a consequence of incorrectly modifying it, leading to DNS resolution problems that could affect any website, not just Substack. They highlight the importance of flushing the DNS cache after modifying the hosts file, and point out that issues can arise from syntax errors or using the wrong IP address. Another commenter echoes this sentiment, emphasizing that general internet connectivity problems stemming from misconfigured hosts files are often misattributed to specific websites.
Another thread of discussion revolves around alternative methods for blocking trackers and ads. Users suggest using browser extensions like uBlock Origin as a more reliable and less error-prone approach compared to modifying the hosts file. They argue that browser extensions are designed specifically for this purpose and offer more granular control. One commenter mentions using a Pi-hole as a network-wide ad-blocking solution, which they find more effective than manipulating the hosts file.
Some commenters delve into the technical details of how DNS resolution works and how modifying the hosts file can interfere with it. One user explains that the hosts file is consulted before other DNS servers, so incorrect entries can override correct DNS records. Another commenter elaborates on the role of the operating system's DNS resolver and how it interacts with the hosts file.
One commenter expresses frustration with the increasing complexity of web development, referencing the numerous tools and technologies involved, including Cloudflare, Fastly, and server-side rendering. They see the Substack issue as a symptom of this complexity.
Finally, a few commenters discuss the potential security implications of relying on the hosts file for blocking trackers. They point out that maintaining an up-to-date hosts file can be challenging and might not be as effective as dedicated security tools.