HaloKeymind/docs/flood_filtering.md

Repeater Flood Filtering and Moderation

This guide explains the Keymind repeater forwarding filters. The filters decide whether this repeater retransmits a packet and can assign a transport scope before that decision. They do not stop local reception, packet logging, or MQTT observation.

Only flood routes are filtered:

• 0x00 / ROUTE_TYPE_TRANSPORT_FLOOD - flood routing with transport codes
• 0x01 / ROUTE_TYPE_FLOOD - unscoped flood routing

Direct routes 0x02 and 0x03 are never affected by these rules. The route and payload values follow the upstream packet-format reference and payload layouts, with this fork's LoRa OTA assignment noted below.

Before making changes

Show the current forwarding controls:

get repeat
get flood.max
get flood.max.unscoped
get flood.max.advert
get flood.channel.data
get flood.channel.data.hops
get flood.channel.block
get flood.channel.scope
get flood.channel.scope.require
get flood.filter
get flood.moderation

The flood.filter and flood.moderation tables each have 16 persistent slots. A new flood.filter table starts with ota all suspend=tempradio in slot 1; flood.moderation starts empty. A row can opt into suspend=tempradio; temporary radio is not synonymous with OTA and can carry normal packet types too. A corrupt or truncated table fails open, so corrupt storage does not silently enable blocking.

Force floods into a transport scope

flood.channel.scope can add a scope to a received unscoped flood or replace the scope of a transport-scoped flood before this repeater forwards it:

set flood.channel.scope <channel|txt:*|login:*|other:*> <region> [path=blacklist|path=bucket:1-6] [tx=slow]
set flood.channel.scope.<slot> <channel|txt:*|login:*|other:*> <region> [path=blacklist|path=bucket:1-6] [tx=slow]
get flood.channel.scope
get flood.channel.scope.<slot>
del flood.channel.scope.<slot>
del flood.channel.scope all

The channel may be public, #channel, or a 128/256-bit hex key. The region must already exist and provide a usable transport key. Keyed rules first check the one-byte channel hash carried in the packet, then validate the MAC by decrypting with the configured channel key. A hash collision alone cannot force a scope.

Add path=blacklist to make a channel-scope row eligible only when the received path matches the passive flood.filter.blacklist ID table. It does not require an enabled flood.filter drop row. With 3-byte paths, one exact listed ID qualifies. With 2-byte paths, two received path entries must match the first two bytes of listed IDs. A 1-byte path never qualifies.

Use path=bucket:<1-6> to match one of the existing flood.retry.bucket tables instead. Each bridge bucket holds up to 17 three-byte IDs and remains usable by channel scoping while flood.retry.bridge is off. Bucket matching uses the same thresholds as the blacklist: one exact hit for 3-byte paths, two qualifying entries for 2-byte paths, and no matches for 1-byte paths. Channel scoping reads the configured IDs directly; recent.repeater freshness and flood.retry.ignore do not change this match.

There are three independent wildcard classes:

• txt:* handles otherwise-unmatched GRP_TXT and GRP_DATA; plain * is its alias.
• login:* handles REQ, RESPONSE, TXT_MSG, ANON_REQ, and PATH.
• other:* handles every remaining flood payload type except TRACE, including OTA. TRACE is deliberately exempt from forced-scope wildcards.

login:* and other:* classify only the visible outer payload type; they do not authenticate its contents. Exact channel rows with usable target regions always take precedence over txt:*, even if that wildcard has a lower slot number. Within the exact class, matching path-qualified rows are tried before ordinary fallback rows. The same qualified-then-fallback order applies within each wildcard class. A missing or unusable target is skipped, so later rows remain eligible. The lowest usable slot wins within each priority tier.

For example, this uses bridge bucket 1 to assign east to public packets whose received 3-byte path contains 7576FB, and assigns west to all other authenticated public packets:

set flood.retry.bucket 1 7576FB
set flood.channel.scope public west
set flood.channel.scope public east path=bucket:1

More 3-byte IDs can be added to bucket 1 later. Any one of them qualifies the east row. Replacing or clearing that bucket changes which paths qualify but leaves both channel-scope rows intact. Bridge retry does not need to be enabled.

On a successful match, an unscoped route changes from ROUTE_TYPE_FLOOD to ROUTE_TYPE_TRANSPORT_FLOOD; an already-scoped route remains transport-flood but receives replacement codes. Transport code 0 is calculated with the target region key over the payload type and payload, and code 1 becomes zero. The change happens before region enforcement, forwarding filters, and deduplication. Consequently flood.max.unscoped no longer applies to a packet converted from unscoped, while flood.max, target-region permissions, flood.filter, channel blocking, loop detection, and moderation still apply to every rewritten packet. By default, if the selected scope differs and the rewritten packet passes those checks, its initial retransmission uses zero txdelay and the highest outbound queue priority so the newly scoped copy can win at the next hop. Add tx=slow to use an effective inbound rxdelay base of max(2, configured rxdelay * 2), retain normal outbound queue priority, and force the maximum txdelay factor of 2.0. The actual transmit delay is still randomized, from zero through ten packet airtimes. It does not preempt an active radio transmission or bypass CAD and airtime-budget limits. Selecting the scope already present is a no-op and does not grant special treatment.

Direct routes are never rewritten. TRACE is never rewritten even in flood form; its existing code, if any, is preserved and it bypasses region/unknown-code enforcement. Scope assignment also does not override normal payload validation or make an otherwise non-forwardable packet type forwardable.

LoRa OTA (0x0C) falls under other:*. A matching row adds the selected transport code or replaces the existing one, but OTA still operates normally during the temporary-radio window because the OTA handler accepts both unscoped and transport-scoped flood routes. The target region must allow flooding. A new repeater also seeds ota all suspend=tempradio in flood-filter slot 1. That visible rule blocks OTA forwarding at every received hop outside temporary-radio operation and is skipped while temporary radio is active. Independently, the OTA core refuses OTA receive, relay, and transmit outside an actually active temporary-radio window, even if the seeded row is deleted or replaced.

Capacity is selected at build time:

• Roomy ESP32 builds: 255 slots, 9,180 bytes RAM, 9,185-byte file.
• DRAM-tight classic ESP32 LoRa-OTA repeaters, nRF52, and other normal constrained builds: 31 slots, 1,116 bytes RAM, 1,121-byte file.
• Very-tight STM32WL builds: 15 slots, 540 bytes RAM, 545-byte file.
• The no-PSRAM LilyGo T-LoRa V2.1 repeater/observer: 4 slots, 144 bytes RAM, 149-byte file. This minimum holds the three wildcard classes and one exact channel mapping.

The region map still has 32 named-region entries. Large ESP32 tables can map many channels to the same targets, but cannot reference more than 32 distinct configured region names.

Require valid incoming scopes only on selected channels

flood.channel.scope.require changes region enforcement for received flood GRP_TXT and GRP_DATA packets from a global policy to a channel opt-in policy:

set flood.channel.scope.require <public|#channel|128/256-bit-key>
set flood.channel.scope.require.<slot> <public|#channel|128/256-bit-key>
get flood.channel.scope.require
get flood.channel.scope.require.<slot>
del flood.channel.scope.require.<slot>
del flood.channel.scope.require all

An empty table preserves the normal global region behavior. Once at least one row exists, a group-channel packet that authenticates against a listed key must arrive as ROUTE_TYPE_TRANSPORT_FLOOD with a transport code matching a locally flood-allowed region. An unscoped packet, an unknown transport code, or a code for a denied region is not retransmitted. The check uses the original incoming scope before flood.channel.scope or flood.filter scope= can rewrite it. Those rewrite actions are skipped for a rejected listed channel, so they cannot rescue it or grant special receive/transmit timing.

Group-channel packets that do not authenticate against any listed key bypass the region/unknown-code forwarding gate. They still pass through repeat, flood.max*, flood.filter, flood.channel.block, loop detection, payload validation, and moderation. Non-channel flood payload types retain the normal global region behavior. A one-byte channel-hash collision is only a prefilter; the packet must also pass MAC validation/decryption with the configured key.

Without .slot, setting an existing key updates its row and a new key uses the first empty row. Numbered set replaces that slot. Detail output displays only the first four derived hash bytes and key size, never the secret. The table has the same build-dependent slot count as flood.channel.scope; each row consumes 34 bytes of RAM and storage, plus a five-byte file header. ACL permission 4 can manage it.

For example, this requires an allowed incoming scope on #bot, while every other group channel bypasses region enforcement:

set flood.channel.scope.require #bot
get flood.channel.scope.require

Interaction with duplicate detection

The seen-packet hash contains the payload type and exact payload bytes. It does not contain the route type, either transport code, or the ordinary flood path. For TRACE only, the encoded path_len byte is also included. Therefore an unscoped packet and the same packet after this repeater adds a transport code are the same duplicate. A later copy with a different scope is also the same duplicate; changing or adding scope cannot evade the seen table.

When equivalent non-TRACE flood copies overlap in rxdelay, the normal receive-quality timing still chooses the packet to process, but that winner takes a scope from the queued copies whose transport code matches an allowed region in this repeater. Unknown and denied scopes are ignored. If eligible copies have different scopes, the shortest received path supplies the scope. Equal path lengths prefer the deepest matching child region (the narrowest configured scope). A remaining tie keeps queue order. The winner keeps its own path, SNR, and delay schedule; only its route and transport codes can change, including replacement of a less-preferred scope it already carried.

Scope selection happens at dequeue so the original scopes remain available for comparison. It applies only while copies are queued and cannot alter a copy already processed into the seen table. TRACE is excluded from scope arbitration entirely, so rxdelay never adds or replaces a trace transport code.

A packet that already matches a configured fast flood.channel.scope or flood.filter scope= action and needs its scope changed bypasses this inbound rxdelay queue entirely. A tx=slow row remains in the queue with twice the configured base, floored at 2.0, and participates in normal queued-copy scope arbitration.

Filter by payload type, received hop count, and path

Use flood.filter when the packet type, current path length, or listed path identifiers are enough to make the decision:

set flood.filter.blacklist <ID[,ID...]>
set flood.filter.blacklist.<slot> <ID[,ID...]>
get flood.filter.blacklist
get flood.filter.blacklist.<slot>
del flood.filter.blacklist
del flood.filter.blacklist.<slot>
set flood.filter <type> [hops] [path=blacklist] [scope=<name>] [require=region] [tx=slow] [suspend=tempradio]
set flood.filter.<slot> <type> [hops] [path=blacklist] [scope=<name>] [require=region] [tx=slow] [suspend=tempradio]
get flood.filter
get flood.filter.<slot>
del flood.filter.<slot>
del flood.filter all

The blacklist holds up to 255 unique 3-byte repeater IDs on ESP32 builds and 18 on other builds. Each is written as six hexadecimal digits. For example:

set flood.filter.blacklist A1B2C3,D4E5F6,112233
set flood.filter.blacklist.4 445566
set flood.filter any all path=blacklist

An unnumbered set replaces the list with up to 18 IDs, the largest command that fits every CLI transport. A numbered set writes a batch of up to 18 IDs beginning at an existing slot or the next consecutive slot. This is how an ESP32 list grows beyond 18. Deleting a numbered entry compacts the entries after it. Unnumbered get reports the total and prints the leading IDs that fit; numbered get retrieves one specific entry.

path=blacklist is an unordered precondition on that row. With 3-byte path hashes, one or more exact blacklist hits qualifies the packet. With 2-byte path hashes, two or more received path entries must match the first two bytes of listed IDs. Each received entry is counted at most once. A 1-byte path never qualifies. The IDs may occur anywhere in the received path; neither their list order nor their path order matters.

Without a slot number, set reuses a rule with the same match, scope, requirement, and suspension settings, or selects the first empty slot. This lets tx=slow or tx=fast change that rule's timing without creating a duplicate. With a slot number, it replaces that slot. Omitting the hop expression means all (0-63).

A row without scope= is the existing drop action. A row with scope= is a scope-setting action instead: it adds transport scope to an unscoped packet or replaces the codes on an already-scoped packet. The scope name is normalized with a leading #, and the 128-bit transport key is derived directly from that hashtag. The name does not need to exist in the region list and is not added to it. Public names up to 30 characters are accepted; private $ scopes are not.

Add require=region to a scope row when rewriting must not rescue a packet that the incoming-region gate would reject. The repeater evaluates the packet's original route before any rewrite in that receive pass. An incoming transport scope must match a locally allowed region; an unscoped flood must be allowed by the wildcard region. If the check fails, that scope row is skipped, the filter does not grant its region bypass, and the unchanged packet is allowed to fail normal region enforcement. Other independently configured scope rows still apply in their normal order.

When multiple scope rows match, the lowest-numbered row wins. Scope rows do not approve a packet: any matching drop row and every remaining forwarding gate can still reject it. A filter-assigned scope is trusted without local region-list validation, but repeat, flood.max, channel blocking, loop detection, and moderation still apply. By default, a changed scope bypasses inbound rxdelay, then is retransmitted with zero txdelay and the highest outbound queue priority. Add tx=slow to use an effective inbound rxdelay base of max(2, configured rxdelay * 2), retain normal queue priority, and force the maximum txdelay factor of 2.0; the randomized transmit delay ranges from zero through ten packet airtimes. tx=fast explicitly restores the default. Selecting the scope already present does not grant special treatment. Active radio transmission, CAD, and airtime-budget limits are unchanged.

The blacklist and rule table are persisted separately. Deleting the blacklist leaves path=blacklist rows in place but dormant until IDs are configured again. Path hashes are truncated routing identifiers and are not authenticated proof that a particular repeater handled a packet.

On first initialization, flood-filter slot 1 is seeded with:

set flood.filter.1 0x0C all suspend=tempradio

This is a normal editable row. After the table has been saved, deleting it remains persistent across reboot; the firmware does not recreate it. Run the same command to restore the exact seeded row, or omit .1 to preserve existing slot assignments and use the first empty slot. Operators may add suspend=tempradio to any other row that should be skipped while the radio is on a temporary channel.

Suspension does not approve a packet or bypass the rest of the filter table. It skips that row, then evaluation continues with the next row and the remaining forwarding gates. An ordinary drop any row therefore still applies during the temporary-radio window, subject to the short-path remote-admin protection below. repeat, flood.max*, region handling, loop detection, and the OTA subsystem's own hop limit also remain in force.

Standard traceroute uses direct routing and never enters flood.filter. For a custom flood-form trace, catch-all any rows are deliberately ignored; only an explicit trace row can match it. The stock core does not normally flood-forward TRACE packets.

Remote administration cannot be type-filtered on short paths

flood.filter drop actions use two minimum filterable hop counts:

• anon_req, path, and response cannot be blocked at received hops 0-6; configured rules begin applying at hop 7.
• Flood txt_msg cannot be blocked at received hops 0-4; configured rules begin applying at hop 5.

req, ack, and multipart ACK have no special floor and remain filterable from hop 0. Scope-setting rows do not block traffic and may apply within the protected ranges.

A flooded login starts as ANON_REQ; its reply is commonly a PATH packet carrying an encrypted RESPONSE. Before a direct return path is established, administrative replies and CLI text can also be flooded. Transit repeaters do not have the session key and cannot distinguish those encrypted admin exchanges from ordinary peer packets with the same outer type. Each hop floor therefore covers the complete outer packet class, not only packets that ultimately authenticate as administrators.

This protects only against configurable flood.filter drop actions. It does not override repeat, flood.max*, loop detection, or other forwarding gates.

Hop expressions are based on the path count when this repeater receives the packet:

• N matches exactly N received hops.
• N+ matches N or more received hops.
• N-M matches the inclusive range.
• all matches 0 through 63 hops.
• 0+, all, and omitting the hop expression are equivalent. get reports the stored range using the canonical spelling all.

Examples:

# Stop forwarding group data once it arrives with four or more path entries.
set flood.filter grp_data 4+

# Stop long adverts, while still allowing shorter adverts.
set flood.filter.2 advert 6+

# Keep LoRa OTA floods from crossing this repeater at path counts 2 through 4.
set flood.filter.3 ota 2-4

# Assign #local scope to group text without requiring #local in the region map.
set flood.filter grp_txt all scope=local

# Rewrite only packets whose incoming region was already acceptable.
set flood.filter grp_data all scope=local require=region

# Rewrite matching blacklisted paths without fast-tracking their retransmission.
set flood.filter grp_data all path=blacklist scope=local tx=slow

# Drop matching flood types after the unordered path blacklist qualifies.
set flood.filter.blacklist A1B2C3,D4E5F6,112233
set flood.filter any all path=blacklist

# Apply a hard ceiling to flood payload types at 12 or more received hops.
set flood.filter any 12+

High-traffic mesh example

This preset limits request and group-data propagation early while allowing the login-capable response, anonymous-request, and path types to travel farther:

set flood.filter req 3+
set flood.filter response 9+
set flood.filter 0x06 3+
set flood.filter 0x07 9+
set flood.filter path 9+
set flood.filter control 1+
get flood.filter

Rule	Stops retransmission when received with
req 3+	3 or more path entries
response 9+	9 or more path entries
0x06 3+ (grp_data)	3 or more path entries
0x07 9+ (anon_req)	9 or more path entries
path 9+	9 or more path entries
control 1+	1 or more path entries

On a new table, the factory OTA rule occupies slot 1, so these unnumbered commands normally fill slots 2 through 7. Existing tables may choose different free slots. The response, anon_req, and path thresholds are above their protected 0-6 range, so all six rules take effect at the thresholds shown. The Control rule allows a flood received with path count 0 to be forwarded once, then stops it at the next repeater. Normal node-discovery Control packets are direct zero-hop packets and never enter flood.filter. These rules affect only retransmission by the repeater; local reception and logging remain unchanged.

Accepted payload names are:

Value	Short name	Full name
0x00	req	PAYLOAD_TYPE_REQ
0x01	response	PAYLOAD_TYPE_RESPONSE
0x02	txt_msg	PAYLOAD_TYPE_TXT_MSG
0x03	ack	PAYLOAD_TYPE_ACK
0x04	advert	PAYLOAD_TYPE_ADVERT
0x05	grp_txt	PAYLOAD_TYPE_GRP_TXT
0x06	grp_data	PAYLOAD_TYPE_GRP_DATA
0x07	anon_req	PAYLOAD_TYPE_ANON_REQ
0x08	path	PAYLOAD_TYPE_PATH
0x09	trace	PAYLOAD_TYPE_TRACE
0x0A	multipart	PAYLOAD_TYPE_MULTIPART
0x0B	control	PAYLOAD_TYPE_CONTROL
0x0C	ota	PAYLOAD_TYPE_OTA in this fork
0x0D	13	reserved
0x0E	14	reserved
0x0F	raw_custom	PAYLOAD_TYPE_RAW_CUSTOM

Decimal values 0 through 15, hexadecimal values 0x00 through 0x0F, the full PAYLOAD_TYPE_* names, and any are also accepted. Upstream currently reserves 0x0C; this fork assigns it to LoRa OTA. Rows are suspended during temporary-radio operation only when explicitly configured that way.

Moderate group text by channel and username

Use flood.moderation for flood GRP_TXT messages. The repeater validates and decrypts the selected channel, extracts the display name before the first :, then applies the rule:

set flood.moderation <channel> <sender> <action> [action...]
set flood.moderation.<slot> <channel> <sender> <action> [action...]
get flood.moderation
get flood.moderation.<slot>
del flood.moderation.<slot>
del flood.moderation all

Channels can be specified as:

• public for the built-in Public channel
• #name for a well-known hashtag channel
• a 128-bit or 256-bit channel key in hexadecimal

The key is stored locally so packets can be authenticated and decrypted. It is not included in get flood.moderation output.

Available actions are:

• drop - do not retransmit any matching message
• rate=X/min - retransmit at most X messages per local 60-second window
• hops=N - do not retransmit when the received path count is N or higher
• path=H1[,H2,H3] - require the first one to three path hashes to match
• path=* - match every path; this is the default

At least one of drop, rate=X/min, or hops=N is required. Rate and hop limits can be combined. rate=0/min is equivalent to drop.

Per-user, per-channel rate limits

Rate limits require an exact username; * is not accepted for a rate rule. Username comparison is ASCII case-insensitive, and names containing spaces must be quoted. A rule's counter is independent from rules for the same name on other channels, so this directly supports "X messages per minute from user X on channel Y." Counters are local to this repeater and reset on reboot.

# At most five Public-channel messages per minute from this display name.
set flood.moderation public "Noisy User" rate=5/min

# A separate limit for the same name on #local.
set flood.moderation #local "Noisy User" rate=10/min

# Combine a rate limit with a maximum forwarding distance.
set flood.moderation public alice rate=4/min hops=5

Match the start of a path

Path matching accepts one-, two-, or three-byte hashes. Every hash in one rule must use the same width, and matching always starts at the beginning of the received path:

set flood.moderation #local bot drop path=A1B2C3,D4E5F6
set flood.moderation public alice rate=3/min path=71

A path-qualified rule cannot match a zero-hop packet and does not match until the packet contains all path entries listed by the rule.

How the forwarding controls combine

A flood packet is retransmitted only if it passes every applicable control. In other words, the controls combine as deny rules:

1. flood.channel.scope.require evaluates a listed group channel against the original incoming scope; unlisted group channels bypass the later region gate while the table is active.
2. flood.channel.scope tries a path-qualified channel row before that channel's ordinary fallback, then adds or replaces the scope.
3. A matching flood.filter scope= row may replace that result; its scope does not require a region-list entry.
4. repeat, flood.max*, and the channel-data gate are checked.
5. flood.filter drop rows check payload type and hop range, subject to the login floor of 7 and flood-text floor of 5 described above.
6. flood.channel.block checks keyed channels.
7. Region and loop-detection rules are checked; a filter-assigned scope is already trusted when it has no region-list match, except that it cannot rescue a channel rejected by flood.channel.scope.require.
8. flood.moderation checks decrypted group text, username, rate, hops, and path.

The first denial is enough to prevent retransmission. A packet that is denied can still appear in local logs or MQTT output. Moderation runs last because its rate counters are charged only for packets that pass every other forwarding control and will actually be retransmitted.

Delegate filter management

ACL permission 5 is the filter-manager role:

setperm <companion-public-key-hex> 5

A filter manager can read non-secret operational status and manage repeat, loop.detect, flood.max*, flood.channel.data*, flood.channel.block*, flood.filter*, and flood.moderation*. Delegated get access uses an explicit allowlist: it cannot retrieve guest, WiFi, MQTT, bridge, or other credentials, and it cannot change regions, ACL entries, radio settings, or unrelated administrator settings. Because flood.filter scope= derives a public hashtag key directly, a filter manager can configure that action without region-manager permission; it still cannot edit the region hierarchy.

ACL permission 4, the region/scope-manager role, can read, add, replace, and delete flood.channel.scope and flood.channel.scope.require rows and manage regions. This lets the same delegate create target regions, assign forced scopes, and select the channels that require valid incoming scopes.

Security limitations

Public and hashtag channels use shared, well-known keys. A valid channel MAC proves that the sender knew the channel key; it does not identify a person. The <sender> value is an unverified display name and can be spoofed. Path hashes are truncated routing hints and can collide or be manipulated; they are not authenticated user identities.

Use username and path rules as traffic moderation, not as an authorization boundary. For a strict network boundary, combine these tools with region ACLs, private transport/channel keys, and controlled device access.

Restore the factory-seeded rows

The repeater's factory-seeded forwarding rows can be restored through the CLI:

set flood.channel.block.1 #wardriving h=4
set flood.filter.1 0x0C all suspend=tempradio

Each command explicitly replaces slot 1 in its own table. Inspect the slot first if it may now contain another rule. To preserve existing slot assignments, omit .1; the command then reuses an identical row or uses the first empty slot.

Remove the custom rules

To save both tables in an empty state:

del flood.filter all
del flood.moderation all
get flood.filter
get flood.moderation

This does not change the older flood.max*, channel-block, loop-detection, or region settings; inspect or reset those separately when troubleshooting.