Wireshark Network Traffic Analysis Purpose Execute comprehensive network traffic analysis using Wireshark to capture, filter, and examine network packets for security investigations, performance optimization, and troubleshooting. This skill enables systematic analysis of network protocols, detection of anomalies, and reconstruction of network conversations from PCAP files. Inputs / Prerequisites Required Tools Wireshark installed (Windows, macOS, or Linux) Network interface with capture permissions PCAP/PCAPNG files for offline analysis Administrator/root privileges for live capture Technical Requirements Understanding of network protocols (TCP, UDP, HTTP, DNS) Familiarity with IP addressing and ports Knowledge of OSI model layers Understanding of common attack patterns Use Cases Network troubleshooting and connectivity issues Security incident investigation Malware traffic analysis Performance monitoring and optimization Protocol learning and education Outputs / Deliverables Primary Outputs Filtered packet captures for specific traffic Reconstructed communication streams Traffic statistics and visualizations Evidence documentation for incidents Core Workflow Phase 1: Capturing Network Traffic Start Live Capture Begin capturing packets on network interface: 1. Launch Wireshark 2. Select network interface from main screen 3. Click shark fin icon or double-click interface 4. Capture begins immediately Capture Controls Action Shortcut Description Start/Stop Capture Ctrl+E Toggle capture on/off Restart Capture Ctrl+R Stop and start new capture Open PCAP File Ctrl+O Load existing capture file Save Capture Ctrl+S Save current capture Capture Filters Apply filters before capture to limit data collection:

Capture only specific host

host 192.168.1.100

Capture specific port

port 80

Capture specific network

net 192.168.1.0/24

Exclude specific traffic

not arp

Combine filters

host 192.168.1.100 and port 443 Phase 2: Display Filters Basic Filter Syntax Filter captured packets for analysis:

IP address filters

ip.addr == 192.168.1.1 # All traffic to/from IP ip.src == 192.168.1.1 # Source IP only ip.dst == 192.168.1.1 # Destination IP only

Port filters

tcp.port == 80 # TCP port 80 udp.port == 53 # UDP port 53 tcp.dstport == 443 # Destination port 443 tcp.srcport == 22 # Source port 22 Protocol Filters Filter by specific protocols:

Common protocols

http # HTTP traffic https or ssl or tls # Encrypted web traffic dns # DNS queries and responses ftp # FTP traffic ssh # SSH traffic icmp # Ping/ICMP traffic arp # ARP requests/responses dhcp # DHCP traffic smb or smb2 # SMB file sharing TCP Flag Filters Identify specific connection states: tcp.flags.syn == 1 # SYN packets (connection attempts) tcp.flags.ack == 1 # ACK packets tcp.flags.fin == 1 # FIN packets (connection close) tcp.flags.reset == 1 # RST packets (connection reset) tcp.flags.syn == 1 && tcp.flags.ack == 0 # SYN-only (initial connection) Content Filters Search for specific content: frame contains "password" # Packets containing string http.request.uri contains "login" # HTTP URIs with string tcp contains "GET" # TCP packets with string Analysis Filters Identify potential issues: tcp.analysis.retransmission # TCP retransmissions tcp.analysis.duplicate_ack # Duplicate ACKs tcp.analysis.zero_window # Zero window (flow control) tcp.analysis.flags # Packets with issues dns.flags.rcode != 0 # DNS errors Combining Filters Use logical operators for complex queries:

AND operator

ip.addr == 192.168.1.1 && tcp.port == 80

OR operator

dns || http

NOT operator

!(arp || icmp)

Complex combinations

(ip.src == 192.168.1.1 || ip.src == 192.168.1.2) && tcp.port == 443 Phase 3: Following Streams TCP Stream Reconstruction View complete TCP conversation: 1. Right-click on any TCP packet 2. Select Follow > TCP Stream 3. View reconstructed conversation 4. Toggle between ASCII, Hex, Raw views 5. Filter to show only this stream Stream Types Stream Access Use Case TCP Stream Follow > TCP Stream Web, file transfers, any TCP UDP Stream Follow > UDP Stream DNS, VoIP, streaming HTTP Stream Follow > HTTP Stream Web content, headers TLS Stream Follow > TLS Stream Encrypted traffic (if keys available) Stream Analysis Tips Review request/response pairs Identify transmitted files or data Look for credentials in plaintext Note unusual patterns or commands Phase 4: Statistical Analysis Protocol Hierarchy View protocol distribution: Statistics > Protocol Hierarchy Shows: - Percentage of each protocol - Packet counts - Bytes transferred - Protocol breakdown tree Conversations Analyze communication pairs: Statistics > Conversations Tabs: - Ethernet: MAC address pairs - IPv4/IPv6: IP address pairs - TCP: Connection details (ports, bytes, packets) - UDP: Datagram exchanges Endpoints View active network participants: Statistics > Endpoints Shows: - All source/destination addresses - Packet and byte counts - Geographic information (if enabled) Flow Graph Visualize packet sequence: Statistics > Flow Graph Options: - All packets or displayed only - Standard or TCP flow - Shows packet timing and direction I/O Graphs Plot traffic over time: Statistics > I/O Graph Features: - Packets per second - Bytes per second - Custom filter graphs - Multiple graph overlays Phase 5: Security Analysis Detect Port Scanning Identify reconnaissance activity:

SYN scan detection (many ports, same source)

ip.src == SUSPECT_IP && tcp.flags.syn == 1

Review Statistics > Conversations for anomalies

Look for single source hitting many destination ports

Identify Suspicious Traffic Filter for anomalies:

Traffic to unusual ports

tcp.dstport > 1024 && tcp.dstport < 49152

Traffic outside trusted network

!(ip.addr == 192.168.1.0/24)

Unusual DNS queries

dns.qry.name contains "suspicious-domain"

Large data transfers

frame.len > 1400 ARP Spoofing Detection Identify ARP attacks:

Duplicate ARP responses

arp.duplicate-address-frame

ARP traffic analysis

arp

Look for:

- Multiple MACs for same IP

- Gratuitous ARP floods

- Unusual ARP patterns

Examine Downloads Analyze file transfers:

HTTP file downloads

http.request.method == "GET" && http contains "Content-Disposition"

Follow HTTP Stream to view file content

Use File > Export Objects > HTTP to extract files

DNS Analysis Investigate DNS activity:

All DNS traffic

dns

DNS queries only

dns.flags.response == 0

DNS responses only

dns.flags.response == 1

Failed DNS lookups

dns.flags.rcode != 0

Specific domain queries

dns.qry.name contains "domain.com" Phase 6: Expert Information Access Expert Analysis View Wireshark's automated findings: Analyze > Expert Information Categories: - Errors: Critical issues - Warnings: Potential problems - Notes: Informational items - Chats: Normal conversation events Common Expert Findings Finding Meaning Action TCP Retransmission Packet resent Check for packet loss Duplicate ACK Possible loss Investigate network path Zero Window Buffer full Check receiver performance RST Connection reset Check for blocks/errors Out-of-Order Packets reordered Usually normal, excessive is issue Quick Reference Keyboard Shortcuts Action Shortcut Open file Ctrl+O Save file Ctrl+S Start/Stop capture Ctrl+E Find packet Ctrl+F Go to packet Ctrl+G Next packet ↓ Previous packet ↑ First packet Ctrl+Home Last packet Ctrl+End Apply filter Enter Clear filter Ctrl+Shift+X Common Filter Reference

Web traffic

http || https

Email

smtp || pop || imap

File sharing

smb || smb2 || ftp

Authentication

ldap || kerberos

Network management

snmp || icmp

Encrypted

tls || ssl

Export Options

File > Export Specified Packets # Save filtered subset

File > Export Objects > HTTP # Extract HTTP files

File > Export Packet Dissections # Export as text/CSV

Constraints and Guardrails

Operational Boundaries

Capture only authorized network traffic

Handle captured data according to privacy policies

Avoid capturing sensitive credentials unnecessarily

Properly secure PCAP files containing sensitive data

Technical Limitations

Large captures consume significant memory

Encrypted traffic content not visible without keys

High-speed networks may drop packets

Some protocols require plugins for full decoding

Best Practices

Use capture filters to limit data collection

Save captures regularly during long sessions

Use display filters rather than deleting packets

Document analysis findings and methodology

Examples

Example 1: HTTP Credential Analysis

Scenario

Investigate potential plaintext credential transmission

1. Filter: http.request.method == "POST"

2. Look for login forms

3. Follow HTTP Stream

4. Search for username/password parameters

Finding

Credentials transmitted in cleartext form data.

Example 2: Malware C2 Detection

Scenario

Identify command and control traffic

1. Filter: dns

2. Look for unusual query patterns

3. Check for high-frequency beaconing

4. Identify domains with random-looking names

5. Filter: ip.dst == SUSPICIOUS_IP

6. Analyze traffic patterns

Indicators

:

Regular timing intervals

Encoded/encrypted payloads

Unusual ports or protocols

Example 3: Network Troubleshooting

Scenario

Diagnose slow web application

1. Filter: ip.addr == WEB_SERVER

2. Check Statistics > Service Response Time

3. Filter: tcp.analysis.retransmission

4. Review I/O Graph for patterns

5. Check for high latency or packet loss

Finding

TCP retransmissions indicating network congestion. Troubleshooting No Packets Captured Verify correct interface selected Check for admin/root permissions Confirm network adapter is active Disable promiscuous mode if issues persist Filter Not Working Verify filter syntax (red = error) Check for typos in field names Use Expression button for valid fields Clear filter and rebuild incrementally Performance Issues Use capture filters to limit traffic Split large captures into smaller files Disable name resolution during capture Close unnecessary protocol dissectors Cannot Decrypt TLS/SSL Obtain server private key Configure at Edit > Preferences > Protocols > TLS For ephemeral keys, capture pre-master secret from browser Some modern ciphers cannot be decrypted passively