Pcap Inspection

A note about PCAP vs PCAPNG: there are two versions of the PCAP file format; PCAPNG is newer and not supported by all tools. You may need to convert a file from PCAPNG to PCAP using Wireshark or another compatible tool, in order to work with it in some other tools.

Online tools for pcaps

Extract Information

The following tools are useful to extract statistic, files...


If you are going to analyze a PCAP you basically must to know how to use Wireshark

You can find some Wireshark trick in:

Xplico Framework

Xplico (only linux) can analyze a pcap and extract information from it. For example, from a pcap file Xplico extracts each email (POP, IMAP, and SMTP protocols), all HTTP contents, each VoIP call (SIP), FTP, TFTP, and so on.


sudo bash -c 'echo "deb $(lsb_release -s -c) main" /etc/apt/sources.list'
sudo apt-key adv --keyserver --recv-keys 791C25CE
sudo apt-get update
sudo apt-get install xplico


/etc/init.d/apache2 restart
/etc/init.d/xplico start

Access to with credentials xplico:xplico

Then create a new case, create a new session inside the case and upload the pcap file.


Like Xplico it is a tool to analyze and extract objects from pcaps. It has a free edition that you can download here. It works with Windows. This tool is also useful to get other information analysed from the packets in order to be able to know what was happening there in a quick way.

NetWitness Investigator

You can download NetWitness Investigator from here (It works in Windows). This is another useful tool that analyse the packets and sort the information in a useful way to know what is happening inside.

  • Extracting and encoding usernames and passwords (HTTP, FTP, Telnet, IMAP, SMTP...)

  • Extract authentication hashes and crack them using Hashcat (Kerberos, NTLM, CRAM-MD5, HTTP-Digest...)

  • Build visual network diagram (Network nodes & users)

  • Extract DNS queries

  • Reconstruct all TCP & UDP Sessions

  • File Carving


capinfos capture.pcap


If you are looking for something inside the pcap you can use ngrep. And example using the main filters:

ngrep -I packets.pcap "^GET" "port 80 and tcp and host 192.168 and dst host 192.168 and src host 192.168"


Using common carving techniques can be useful to extract files and information from the pcap:

Capturing credentials

You can us tools like to parse credentials from a pcap or a live interface.

Check Exploits/Malware


Install and setup

apt-get install suricata
apt-get install oinkmaster
echo "url =" >> /etc/oinkmaster.conf
oinkmaster -C /etc/oinkmaster.conf -o /etc/suricata/rules

Check pcap

suricata -r packets.pcap -c /etc/suricata/suricata.yaml -k none -v -l log


YaraPCAP is a tool that

  • Reads a PCAP File and Extracts Http Streams.

  • gzip deflates any compressed streams

  • Scans every file with yara

  • writes a report.txt

  • optionally saves matching files to a Dir

Malware Analysis

Check if you can find any fingerprint of a known malware:


Zeek is a passive, open-source network traffic analyzer. Many operators use Zeek as a network security monitor (NSM) to support investigations of suspicious or malicious activity. Zeek also supports a wide range of traffic analysis tasks beyond the security domain, including performance measurement and troubleshooting.

Basically, logs created by zeek aren't pcaps. Therefore you will need to use other tools to analyse the logs where the information about the pcaps are.

Connections Info

#Get info about longest connections (add "grep udp" to see only udp traffic)
#The longest connection might be of malware (constant reverse shell?)
cat conn.log | zeek-cut id.orig_h id.orig_p id.resp_h id.resp_p proto service duration | sort -nrk 7 | head -n 10 49778 443 tcp - 86222.365445 56099 443 tcp - 86220.126151 60168 443 tcp - 86160.119664
#Improve the metrics by summing up the total duration time for connections that have the same destination IP and Port.
cat conn.log | zeek-cut id.orig_h id.resp_h id.resp_p proto duration | awk 'BEGIN{ FS="\t" } { arr[$1 FS $2 FS $3 FS $4] += $5 } END{ for (key in arr) printf "%s%s%s\n", key, FS, arr[key] }' | sort -nrk 5 | head -n 10 443 tcp 86222.4 443 tcp 86220.1 443 tcp 86160.1
#Get the number of connectionssummed up per each line
cat conn.log | zeek-cut id.orig_h id.resp_h duration | awk 'BEGIN{ FS="\t" } { arr[$1 FS $2] += $3; count[$1 FS $2] += 1 } END{ for (key in arr) printf "%s%s%s%s%s\n", key, FS, count[key], FS, arr[key] }' | sort -nrk 4 | head -n 10 1 86222.4 1 86220.1 134 86160.1
#Check if any IP is connecting to
cat conn.log | zeek-cut id.orig_h id.resp_h id.resp_p proto service | grep '' | sort | uniq -c
#Get number of connections per source IP, dest IP and dest Port
cat conn.log | zeek-cut id.orig_h id.resp_h id.resp_p proto | awk 'BEGIN{ FS="\t" } { arr[$1 FS $2 FS $3 FS $4] += 1 } END{ for (key in arr) printf "%s%s%s\n", key, FS, arr[key] }' | sort -nrk 5 | head -n 10
### RITA
#Something similar can be done with the tool rita
rita show-long-connections -H --limit 10 zeek_logs
| | | 443:tcp:- | 23h57m2.3655s |
| | | 443:tcp:- | 23h57m0.1262s |
| | | 443:tcp:- | 23h56m0.1197s |
#Get connections info from rita
rita show-beacons zeek_logs | head -n 10
Score,Source IP,Destination IP,Connections,Avg Bytes,Intvl Range,Size Range,Top Intvl,Top Size,Top Intvl Count,Top Size Count,Intvl Skew,Size Skew,Intvl Dispersion,Size Dispersion

DNS info

#Get info about each DNS request performed
cat dns.log | zeek-cut -c id.orig_h query qtype_name answers
#Get number of times each domain was requestedand get top 10
cat dns.log | zeek-cut query | sort | uniq | rev | cut -d '.' -f 1-2 | rev | sort | uniq -c | sort -nr | head -n 10
#Get all the IPs
cat dns.log | zeek-cut id.orig_h query | grep 'example\.com' | cut -f 1 | sort | uniq -c
#Sort the most common dnsrecord request (should be A)
cat dns.log | zeek-cut qtype_name | sort | uniq -c | sort -nr
#See top DNS domain requested with rita
rita show-exploded-dns -H --limit 10 zeek_logs

Other pcap analysis tricks