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fix: reject negative SNMP values and reset baseline on counter type f… #7

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Merged
coreyeaston merged 1 commit into from
Feb 5, 2026
Merged

fix: reject negative SNMP values and reset baseline on counter type f… #7

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10 changes: 7 additions & 3 deletions backend/app/services/snmp_monitor.py
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Original file line number Diff line number Diff line change
Expand Up @@ -361,6 +361,10 @@ async def get_bandwidth(self) -> Optional[Dict[str, float]]:
if in_octets is None and self._use_64bit:
logger.info("64-bit counters unavailable, falling back to 32-bit")
self._use_64bit = False
# Reset baseline to avoid incorrect delta between different counter types
self._last_in_octets = None
self._last_out_octets = None
self._last_poll_time = None
in_oid = IF_IN_OCTETS
out_oid = IF_OUT_OCTETS
results = await self._get_multiple_oids([in_oid, out_oid], self.config.interface)
Expand Down Expand Up @@ -406,10 +410,10 @@ async def get_bandwidth(self) -> Optional[Dict[str, float]]:
download_mbps = (in_delta / time_diff) * 8 / 1_000_000
upload_mbps = (out_delta / time_diff) * 8 / 1_000_000

# Sanity check: reject unreasonably high values (> 10 Gbps)
# This catches counter wrap-around issues or calculation errors
# Sanity check: reject negative or unreasonably high values (> 10 Gbps)
# This catches counter wrap-around issues, counter type switching, or calculation errors
MAX_REASONABLE_MBPS = 10000 # 10 Gbps
if download_mbps > MAX_REASONABLE_MBPS or upload_mbps > MAX_REASONABLE_MBPS:
if download_mbps < 0 or upload_mbps < 0 or download_mbps > MAX_REASONABLE_MBPS or upload_mbps > MAX_REASONABLE_MBPS:
logger.warning(
f"SNMP: Rejecting unreasonable values - {download_mbps:.2f} Mbps down, {upload_mbps:.2f} Mbps up "
f"(in_delta={in_delta}, out_delta={out_delta}, time_diff={time_diff:.2f}s). "
Expand Down