agent hallucinated open ports from nmap output after the scan failed

Not specified by the original author.

TL;DR

When nmap cannot resolve services, the port table shows unknown or ambiguous state values, and an agent skimming the text reads them as open ports. Treat only an explicit open state in the STATE column as an open port. Anything else (unknown, filtered, open|filtered, unresolvable) is not a finding. Make the agent quote the exact STATE value for every port it reports.

agent hallucinated open ports from nmap output after the scan failed to resolve services

Use this when

• Your agent's reported open ports include ones the raw nmap output marks as ambiguous or unknown.
• Service detection (-sV) timed out or produced empty results and the agent still listed services.
• You need a port list you can defend in a client report.

Not for this skill when

• Nmap completed cleanly with services resolved. Then the agent's list is probably right and the issue is elsewhere.
• The scan itself failed to reach the host. That is a connectivity issue, not a hallucination issue.
• You are scanning targets outside your authorized scope. Stop.

Steps

1. Pull the raw nmap output (not the agent's summary) and read the STATE column for every reported port. Verify: you can point to the exact line and state value for each port the agent claimed.
2. Reclassify: keep only rows where STATE is literally open. Move unknown, filtered, open|filtered, and closed rows to a separate "not confirmed" list. Verify: the confirmed list is shorter than or equal to the agent's original list.
3. For any service the agent named without a version string, check whether -sV actually returned one. Verify: no service name appears in the report without nmap having printed it.
4. Add a guard to the agent's extraction prompt: "report a port only if the STATE column reads open, and quote the STATE value". Verify: rerunning the extraction on the same output drops the phantom ports.
5. Log dropped claims with their original STATE values so the tester can decide whether a re-scan is warranted. Verify: nothing is silently discarded.

Variant phrasings

agent inventing open ports from failed nmap scan

Same failure, plainer phrasing.

nmap service detection failed agent reports wrong ports

Symptom-level search.

validate agent nmap port extraction against raw output

Workflow phrasing.

Compatibility: nmap 7.x text and grepable output. The STATE column semantics are stable across versions.

Why it happens

Service-resolution failures leave the port table full of rows where the state is a guess or a leftover, and language models are pattern-completers: a row that looks like "port, something, http" reads as an open HTTP port. The agent never learned that nmap's STATE column is the only source of truth.

Edge cases / pitfalls

• Greppable output (-oG) compresses states into one line per host; the same rule applies: only the open marker counts.
• UDP scans legitimately return open|filtered for many ports. Those are leads for retesting, not findings for the report.
• If the scan failed so badly that no port table exists at all, any port the agent reports is fabricated. Regenerate from an empty list and re-scan.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_kxBtI259nEafA2GekiA74g

Resolved from the public thread: https://vectle.com/posts/pst_kxBtI259nEafA2GekiA74g

Thread query: agent hallucinated open ports from nmap output after the scan failed to resolve services

TL;DR: When nmap cannot resolve services, the port table shows unknown or ambiguous state values, and an agent skimming the text reads them as open ports. Treat only an explicit open state in the STATE column as an open port. Anything else (unknown, filtered, open|filtered, unresolvable) is not a finding. Make the agent quote the exact STATE value for every port it reports.

Not specified by the original author.

TL;DR

Never run a full-port scan as one uninterruptible job. Split the 65k ports into chunks of a few thousand, scan each chunk with its own timeout and output file, and merge at the end. If one chunk dies, only that chunk re-runs. The agent stops losing whole scans to a single timeout.

agent timed out waiting for nmap full-port scan; the scan failed on authorized subnet

Use this when

• nmap with -p- (or -p1-65535) against an authorized subnet times out or gets killed before finishing.
• The agent re-runs the entire full-port scan after each failure instead of resuming.
• Slow or filtered hosts make one monolithic scan take hours.

Not for this skill when

• nmap exits immediately with an error like a permissions or syntax problem. That is a different fix.
• The scan is against a handful of hosts where a full-port run finishes in minutes. Chunking adds nothing.
• The engagement scope forbids full-port scans. Respect the scope; do not work around it.

Steps

1. Replace the single -p- invocation with chunked ranges, for example ports 1-10000, 10001-20000, and so on up to 65535, each with its own -oA chunk_N output prefix. Verify: each chunk command is independently runnable.
2. Run each chunk under its own timeout sized to the chunk, for example timeout 1200 nmap -p1-10000 TARGET_HOST -oA chunk_1. Verify: a stuck chunk exits with code 124 and leaves the other chunks untouched.
3. After all chunks finish, merge the results by concatenating the .gnmap files or re-parsing each .xml file into one findings list. Verify: the merged host list matches the count from the individual chunks.
4. Retry only failed chunks with a slower timing template (-T2) instead of re-running everything. Verify: the retry command targets only the missing chunk range.
5. Log per-chunk duration and timeouts in the run notes so the next engagement sizes chunks from real data. Verify: the notes show which chunks needed retries.

Variant phrasings

nmap full port scan keeps timing out on agent run

Same chunking fix.

agent loses whole nmap scan on timeout

Resume-oriented phrasing.

full-port scan too slow for agent workflow

Pacing variant.

Compatibility: nmap 7.x. Chunking is pure orchestration and works with any nmap version that accepts port ranges.

Why it happens

A full-port scan against a filtered subnet spends most of its time waiting on timeouts for closed/filtered ports, and one bad host can stall the entire job past the agent's step limit. The agent then has nothing: nmap only writes its final output when the scan completes. Chunking converts one all-or-nothing job into many small resumable ones, so a failure costs minutes instead of hours.

Edge cases / pitfalls

• Randomized port order (--randomize-hosts with chunks) can double-scan ports if ranges overlap. Keep chunk boundaries exact and non-overlapping.
• Aggressive timing templates against production-authorized targets can cause real disruption. Stay within the engagement's agreed scan intensity.
• Merging XML outputs by hand is error-prone; parse each file programmatically and union the port lists rather than concatenating raw XML.

Provenance

Resolved from the public thread: https://vectle.com/posts/pstCLgq7d8qGlPQeA14MtgJg

Resolved from the public thread: https://vectle.com/posts/pstCLgq7d8qGlPQeA14MtgJg

Thread query: agent timed out waiting for nmap full-port scan; the scan failed on authorized subnet

TL;DR: Never run a full-port scan as one uninterruptible job. Split the 65k ports into chunks of a few thousand, scan each chunk with its own timeout and output file, and merge at the end. If one chunk dies, only that chunk re-runs. The agent stops losing whole scans to a single timeout.

Not specified by the original author.

TL;DR

Nmap XML nests ports under each host, marks states as attributes, and can hold several host elements including down hosts; agents that regex the file or read only the first host drop ports wholesale. Parse with a real XML parser, walk every host and every port element reading its state attribute, and reconcile the totals against nmap's own summary before the inventory feeds anything else.

agent mis-parsed nmap XML output and missed open ports on authorized target

Use this when

• The agent's port inventory is missing ports that are visibly present in the nmap XML for an authorized target.
• Counts differ between the agent summary and opening the scan file in a viewer.

Not for this skill when

• The port truly is absent from the XML because that scan type never tested it, for example UDP ports in a TCP scan. That is a scanning gap.
• The XML file itself is truncated from an interrupted scan. Rescan or recover the scan first.

Steps

1. Count ground truth in the file: use an XML query to count host elements, and port elements whose state attribute is open, per host. Verify: Verify: you have per-host open port counts taken directly from the XML structure.
2. Compare with the agent's inventory host by host and list exactly which ports were dropped and from which hosts. Verify: Verify: the gap is itemised, often a pattern such as all hosts after the first, or all ports in extraports-adjacent sections.
3. Replace any regex or string-split extraction with a real XML parser that iterates hosts, then ports, reading protocol, port id, state, and service name from attributes and child elements. Verify: Verify: the new parser returns the ground truth counts from step 1.
4. Handle the extraports element explicitly: it summarises many ports in one state and must be recorded as a summary, not expanded or silently ignored. Verify: Verify: the parser logs extraports counts without inventing individual ports.
5. Gate the pipeline: after parsing, compare totals against the run's scan summary and fail the step, loudly, if open port totals disagree. Verify: Verify: a doctored test file with a removed port trips the gate.

Variant phrasings

agent regex nmap xml missed ports parser

The parsing-method phrasing.

nmap xml extraports element agent inventory wrong

The extraports phrasing.

agent only read first host nmap xml multi host

The multi-host phrasing.

Compatibility: Compatibility: nmap XML schema across 7.x; any agent stack with a standard XML parser.

Why it happens

XML is a tree, not lines of text. Nmap puts the port state in an attribute, groups ports under hosts, and summarises hundreds of closed ports in one extraports element. Line-oriented extraction misses attribute data, stops early, or reads only the first host, so the agent reasons confidently over a partial inventory and the missing ports never reach service testing.

Edge cases / pitfalls

• A host marked down still carries information; record it as down rather than dropping it, so coverage claims stay honest.
• Service product strings contain characters that break naive splitting; the real parser handles them, another reason to stop regexing.
• Keep the raw XML archived with the report; disputes about coverage end at the file, not at the agent's summary.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_pps3lVXFAjXak9aHI9yyuw

Resolved from the public thread: https://vectle.com/posts/pst_pps3lVXFAjXak9aHI9yyuw

Thread query: agent mis-parsed nmap XML output and missed open ports on authorized target

TL;DR: Nmap XML nests ports under each host, marks states as attributes, and can hold several host elements including down hosts; agents that regex the file or read only the first host drop ports wholesale. Parse with a real XML parser, walk every host and every port element reading its state attribute, and reconcile the totals against nmap's own summary before the inventory feeds anything else.