Cybersecurity & Information Security

Display Filters in Wireshark: Useful Filters for Incident Investigation

6 min readPublished: August 5, 2026

Professional visual illustration of Wireshark Display Filters in Network Security Monitoring

Quick answer

Wireshark Display Filters are used by mapping Flow, timings, protocols, DNS/TLS/HTTP, and asset context. A single packet or connection is partial evidence, so a sequence is built and validated against additional sources.

Network traffic provides a perspective that is not solely dependent on the endpoint. It allows identifying who communicated with whom, using what protocol, in what order, and in what volume, but requires an understanding of the limits of visibility and encryption. This article focuses on Wireshark Display Filters and is intended for analysts and network students. The goal is to provide a working method that can be applied in practice, in professional interviews, and in a work environment, without settling for a dictionary definition.

The main challenge is that data is almost always partial. Protocol Hierarchy, Endpoints, Conversations can indicate a direction, but their meaning depends on the time, asset, user, and expected activity. Therefore, we will build the examination around an investigative question, required evidence, and a clear criterion for completion.

The practical scenario in the article is: a set of filters for detecting Beaconing and anomalous DNS. All examples are laboratory data or process descriptions. When dealing with Penetration Testing, Web, or Cloud, one must only work with explicit authorization, a defined scope, and the ability to stop the test.

Display Filter Structure

The important fields are not necessarily those displayed at the top of the screen. In Wireshark Display Filters, stable identifiers, time, source, destination, result, and context must be identified. Useful examples include Protocol Hierarchy, Endpoints, Conversations, Display Filters, Follow Stream, Expert Information. The goal is to enable correlation between records and not just reading a single event.

It is recommended to create a small Data dictionary: field name, meaning, format, source, expected Null values, and whether it is reliable for linking. This allows distinguishing between a display field and an investigative identifier, and identifying when a Connector or version has changed Schema.

Filters for IP and TCP

The topic 'Filters for IP and TCP' is a central part of working with Wireshark Display Filters. It is recommended to break it down into three questions: What is the input, what decision do you want to make, and what evidence is sufficient to justify it? These questions prevent automatic use of the tool without understanding the purpose.

In practice, record the Protocol Hierarchy, Endpoints, Conversations, Display Filters, Follow Stream, compare with expected behavior, and define at least one Pivot. The result should be verifiable by another analyst, including limitations and next steps.

Filters for DNS and HTTP

The topic 'Filters for DNS and HTTP' is a central part of working with Wireshark Display Filters. It is recommended to break it down into three questions: What is the input, what decision do you want to make, and what evidence is sufficient to justify it? These questions prevent automatic use of the tool without understanding the purpose.

Filters for Errors and Retransmissions

The topic 'Filters for Errors and Retransmissions' is a central part of working with Wireshark Display Filters. It is recommended to break it down into three questions: What is the input, what decision do you want to make, and what evidence is sufficient to justify it? These questions prevent automatic use of the tool without understanding the purpose.

Combining Conditions and Saving Filters

The topic 'Combining Conditions and Saving Filters' is a central part of working with Wireshark Display Filters. It is recommended to break it down into three questions: What is the input, what decision do you want to make, and what evidence is sufficient to justify it? These questions prevent automatic use of the tool without understanding the purpose.

Unique Inspection Focus Areas

In this topic, it is recommended to build a focused evidence map in advance. The main inspection points are: Protocol Hierarchy, Endpoints, Conversations, Display Filters, Follow Stream, Expert Information. The list is not an automatic Checklist; each item is chosen because it can link an entity, action, and time or explain legitimate behavior.

Protocol Hierarchy: Define the expected value, what would be considered anomalous, and what additional source would validate the finding.
Endpoints: Define the expected value, what would be considered anomalous, and what additional source would validate the finding.
Conversations: Define the expected value, what would be considered anomalous, and what additional source would validate the finding.
Display Filters: Define the expected value, what would be considered anomalous, and what additional source would validate the finding.
Follow Stream: Define the expected value, what would be considered anomalous, and what additional source would validate the finding.
Expert Information: Define the expected value, what would be considered anomalous, and what additional source would validate the finding.

When one of the focus areas is unavailable, the gap should be documented and an alternative chosen. For example, if a Process identifier is not stable, one can use time, Host, User, and Parent; if the Payload is encrypted, metadata, volume, frequency, and TLS/DNS context are used.

Recommended Workflow

Define a Scope and one working question related to Wireshark Display Filters.
List the data sources and required evidence: Protocol Hierarchy, Endpoints, Conversations, Display Filters.
Create a short Baseline of normal behavior or expected outcome.
Perform the minimal test in a lab environment and save time, input, and output.
Build a Timeline or comparison table and separate fact from interpretation.
Pivot to an additional source to confirm or refute the initial explanation.
Summarize the decision, limitations, recommended action, and Retest criterion.

Practical Scenario

The chosen scenario is a set of filters for detecting Beaconing and anomalous DNS. The purpose of the exercise is not to prove an attack capability, but to practice collecting, comparing, and documenting safely. Before starting, define simulated data, a time window, and an expected outcome.

At the end of the exercise, a deliverable that another analyst or tester can review should be submitted: a screenshot or Export of the evidence, a short Timeline, an initial hypothesis, corroborating evidence, a limitation, and a recommendation. When there is insufficient evidence, the correct conclusion is that the scenario was not proven.

Step	What to do	Deliverable
Preparation	Define Scope, time, and target. List which fields or evidence from Protocol Hierarchy, Endpoints, Conversations are expected to appear.	Short test plan
Data Generation	Perform a safe, simulated action related to Wireshark Display Filters, without real information or impact on a production system.	Controlled event/Request/Flow
Collection	Collect the raw evidence and context from an additional source. Verify Time zone, identifiers, and integrity.	Two linked pieces of evidence
Analysis	Write what each piece of evidence proves, what it doesn't prove, and what the possible legitimate explanation is.	Interim conclusion
Completion	Choose closure, escalation, Finding or Tuning; add a recommendation and Retest.	Documented deliverable

Practical Checklist

Check and document: the five components of the Flow.
Check and document: start time, duration, and volume.
Check and document: DNS name and TLS metadata.
Check and document: HTTP method, host, and URI when visible.
Check and document: TCP flags and stream.
Check and document: connection to Host and Process.
Note Time zone, tool version, and collection time.
Save the raw data before filtering or modification.
Write what the finding proves and what is still unknown.
Define owner and next action with a deadline.

Common Mistakes

Confusing Capture Filter with Display Filter.
Inferring content when traffic is encrypted.
Analyzing IP without DNS/TLS context.
Ignoring NAT or Proxy.
Focusing on a single Packet.
Not saving the original Capture.

Summary and CTA

Display Filters in Wireshark: Useful Filters for Incident Investigation is a topic that connects technical knowledge with work discipline. Start with a question, collect only relevant evidence, maintain context and time, and choose an action that can be justified and re-verified.

In HPI's Cybersecurity & AI track, these principles are practiced using systems, logs, and labs. A natural next step is to move on to the linked articles, complete the lab exercise, and save the output as part of a professional portfolio.

FAQ

Does Wireshark Display Filters alone prove an attack or vulnerability?

No. It provides a signal or finding that requires context, validation, and an additional source. A professional conclusion relies on a sequence of evidence and alignment with expected behavior.

What to do when some data is missing?

Document the missing data, check an alternative source, and reduce the level of certainty. Do not complete fields with assumptions or present Unknown as normal.

How long should evidence be retained?

The time depends on policy, regulation, cost, and event type. It is important to define Retention, Legal hold, and the ability to export evidence in a verifiable format in advance.

How to practice without endangering a real system?

Use virtual machines, simulated data, CTF, or a dedicated lab. For authorized tests, define Scope, Stop conditions, and backup before starting work.