docs: warn about firehol_level1 RFC1918 gotcha in default blocklist#467
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9seconds merged 2 commits into9seconds:masterfrom Apr 14, 2026
Merged
docs: warn about firehol_level1 RFC1918 gotcha in default blocklist#4679seconds merged 2 commits into9seconds:masterfrom
9seconds merged 2 commits into9seconds:masterfrom
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The default [defense.blocklist] uses firehol_level1.netset, which includes bogon networks and therefore all RFC1918 ranges. Clients connecting from a LAN address (e.g. a phone on the home Wi-Fi when mtg runs at home) are silently rejected with "ip was blacklisted" and routed to the fronting domain. This is a recurring source of confusion (see issue 9seconds#466 for the latest example). Add a warning next to the urls list in example.config.toml and a Troubleshooting section in README.md covering the symptom, the cause, and three resolution paths (disable blocklist, swap for a narrower list, or use hairpin NAT). Docs only, no code changes.
The previous wording ("silently routed to the fronting domain")
is inaccurate. In mtglib/proxy.go the blocklist path calls
conn.Close() immediately with no further handshake or fronting;
domain fronting only happens on FakeTLS failures for non-blocked
IPs. Reword to "TCP connection is closed with no response" so
users searching the docs get the same symptom they actually see.
dolonet
added a commit
to dolonet/mtg-multi
that referenced
this pull request
Apr 15, 2026
Upstream commits included: - 0c1d001 Add docker-compose example with HAProxy SNI router - d0412b2 Fix ACME HTTP-01 passthrough in HAProxy config - 602f85d Document firehol_level1 RFC1918 gotcha in blocklist defaults - 68a4685 Fix description of blocklist rejection behavior - 170346b Pass real client IPs through with PROXY protocol v2 - 5953f93 Merge PR 9seconds#462 from dolonet/contrib/docker-sni-router - 9bf7222 Merge PR 9seconds#467 from dolonet/docs/blocklist-lan-gotcha Conflict resolution: README.md kept as fork version (mtg-multi has its own README describing multi-secret and per-user stats features). example.config.toml auto-merged cleanly.
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Summary
Follow-up to #466. The default
[defense.blocklist]usesfirehol_level1.netset, which includes bogon networks and therefore all RFC1918 ranges. Clients connecting from the same LAN as mtg (typical home setup: phone on Wi-Fi, mtg on a home server) are silently rejected withip was blacklistedand routed to the fronting domain. This keeps tripping people up.This PR is docs-only and does not change the default behavior:
example.config.toml: a shortNOTEblock next to[defense.blocklist].urlsdescribing the gotcha and pointing to the README.README.md: a new## Troubleshootingsection before## Metricswith the symptom (including the exact log line), the cause, and three resolution paths (disable the blocklist, swap for a narrower list likefirehol_abusers_1d, or use hairpin NAT).No defaults are changed — that is a separate discussion and I didn't want to couple it with a doc fix. Happy to open a follow-up issue/PR if you'd like to revisit the default list choice.
Refs #466.
Test plan
example.config.tomlstill parses as TOML (only comment lines added).