Packet Captures
Various Pcap files for studies are as follows:
PCAP files
Common packet captures files used across the site and for studies are below:
VPN Captures
| Packet Type | Description | Page Link |
|---|---|---|
| ScreenOS Site to Site VPN | Main Mode VPN negotiations (FW1 is Responder; FW2 is Initiator) | VPN Lab, Debug |
| Dialup VPN | Aggressive mode Dailup VPN | VPN Lab, Debug |
| Aggressive Mode VPN | ||
| Dailup Xauth IP VPN | Aggressive mode Dailup VPN with XAuth IP Assignment | VPN Lab, Debug |
| Dailup Xauth IP VPN | Aggressive mode Dailup VPN with XAuth User login | VPN Lab, Debug |
| NAT Traversal | NAT Traversal on Cisco Routers | VPN Lab, Debug |
| Manual Key VPN | Manual Key or Static VPN captures | Manual Key VPN |
FTP-TFTP
| Packet Type | Description | Page Link |
|---|---|---|
| Active Mode FTP | FTP in Active Mode | Active FTP |
| Passive Mode FTP | FTP in Passive Mode | Passive FTP |
| TFTP RRQ | TFTP Read Request | TFTP |
| TFTP WRQ | TFTP Write Request | TFTP |
Routing Protocols
| Packet Type | Description | Page Link |
|---|---|---|
| BGP | BGP | |
| eBGP | BGP | |
| BGP Notification | BGP | |
| BGP MD5 | BGP | |
| OSPF | OSPF | |
| OSPF MD5 | OSPF | |
| OSPF LSAs | OSPF | |
| OSPF over GRE Tunnel | OSPF | |
| EIGRP Neighbors | EIGRP | |
| EIGRP adjacency | EIGRP | |
| EIGRP goodbye | EIGRP | |
| EIGRPv2 adjacency | EIGRP | |
| RIPv1 | ||
| RIPv2 |
ARP
| Packet Type | Description | Page Link |
|---|---|---|
| ARP | ARP | |
| ARP Storm | ARP | |
| Gratuitous ARP | ARP | |
| Gratuitous ARP HSRP | ARP | |
| RARP Request | ARP |
DNS-DHCP
| Packet Type | Description | Page Link |
|---|---|---|
| DNS Capture | Contains TXT, MX, LOC, PTR, A, AAAA, Any, NS, SRV queries | DNS |
| DHCP | All packets broadcast implementation | DHCP |
| DHCP 2 | Unicast packets implementation | DHCP |
| DHCP Inter VLAN | DHCP | |
| Dhcp-auth | DHCP |
Misc Captures
| Packet Type | Description | Page Link |
|---|---|---|
| TCP SACK | SACK(frame #31), Timestamp | TCP/IP |
| Smtp | ||
| Teardrop | ||
| Telnet | ||
| Port Scan | ||
| Traceroute | Traceroute | |
| Path MTU | Fragmentation Needed message in packet #6 | Path MTU Discovery |
| HTTP | Sack Used | HTTP |
| NAT | Ping Packet with & without NAT | |
| IP Fragmentation | ||
| SNMP | ||
| SIP | ||
| GRE Encapsulated Ping | ||
| RADIUS | ||
| DTP | ||
| Slammer Worm | ||
| GLBP election | ||
| HDLC | ||
| HSRP | ||
| HSRP election | ||
| HSRP failover | ||
| Hsrp-and-ospf-in-LAN | ||
| RADIUS2 | ||
| SSHv2 | ||
| TACACS+ | ||
| Bittorrent | ||
| IPv6 | ||
| Vnc-sample | ||
| Blaster Worm | ||
| OS Fingerprinting | ||
| STP | ||
| MySQL |
Filtering Packets
Information related to Packet filtering is as follows:
Filtering a Cap File
dumpcap -i eth0 -f "host 208.67.220.220 and udp port 53" -w /tmp/dns.cap -b duration:3600 -b files:25
Wireshark Common Filters
Sets a filter for any packet with 10.0.0.1, as either the source or dest
ip.addr == 10.0.0.1
Sets a conversation filter between the two defined IP addresses:
ip.addr==10.0.0.1 && ip.addr==10.0.0.2
Sets a filter to display all http and dns:
http or dns
Sets a filter for any TCP packet with 4000 as a source or dest port:
tcp.port==4000
Displays all TCP resets:
tcp.flags.reset==1
Displays all HTTP GET requests:
http.request
Displays all TCP packets that contain the word ‘traffic’. Excellent when searching on a specific string or user ID:
tcp contains traffic
Masks out arp, icmp, dns, or whatever other protocols may be background noise. Allowing you to focus on the traffic of interest:
!(arp or icmp or dns)
Sets a filter for the HEX values of 0x33 0x27 0x58 at any offset:
udp contains 33:27:58
Displays all retransmissions in the trace. Helps when tracking down slow application performance and packet loss:
tcp.analysis.retransmission
Fragmented Traffic:
ip.flags.mf == 1 or ip.frag_offset > 0
ICMP Fragmentation needed packets:
icmp.type==3 and icmp.code==4
Combination of above two:
ip[0,9,20:2]==4501:0304||ip[6:2]&3fff
Starting and Ending sessions:
tcp.flags&7 or (tcp.seq==1 and tcp.ack==1 and !tcp.window_size_scalefactor==-1 and tcp.len==0)
Wireshark Column Filters
| Value to display | Filter |
|---|---|
| TTL | ip.ttl |
| Flags | tcp.flags |
| SEQ | tcp.seq |
| ACK | tcp.ack |
| MSS | tcp.options.mss_val |
| In-Flight | tcp.analysis.bytes_in_flight |
| Payload | tcp.len |
| Window | tcp.window_size |
| Content-Length | http.content_length_header |
TCPDump Filters
Source: [thegeekstuff.com]
| Description | Command |
|---|---|
| General TCPDump command | tcpdump -s 0 -w packet_capture.cap |
| Capture packets from a particular interface | tcpdump -i eth1 |
| Capture only N number of packets | tcpdump -c 200 -i eth0 |
| Display Captured Packets in ASCII | tcpdump -A -i eth0 |
| Display Captured Packets in HEX and ASCII | tcpdump -XX -i eth0 |
| Capture the packets and write into a file | tcpdump -w 08232010.pcap -i eth0 |
| Capture packets with IP address without DNS resolution | tcpdump -n -i eth0 |
| Capture packets with proper readable timestamp | tcpdump -n -tttt -i eth0 |
| Read packets only longer or smaller than N bytes | tcpdump -w capture.pcap greater 1024 tcpdump -w capture.pcap less 1024 |
| Receive only the packets of a specific protocol type | tcpdump -i eth0 arp |
| Receive packets flows on a particular port | tcpdump -i eth0 port 22 |
| Capture packets for particular destination IP and Port | tcpdump -w xpackets.pcap -i eth0 dst 10.181.140.216 and port 22 |
| Capture TCP communication packets between two hosts | tcpdump -w comm.pcap -i eth0 udp and \(host 172.20.68.176 and host 172.24.173.9\) |
| Filter Packets – Capture all the packets other than arp and rarp | tcpdump -i eth0 not arp and not rarp 'and' 'or' and 'not' condition are used to filter the packets |
Reading PCAPs
| Header text | Header text |
|---|---|
| Reading pcap file | tcpdump -r data.pcap |
| Viewing all headers | tcpdump -e -nn -vv -r data.pcap |
| Viewing hexadecimal data | tcpdump -XX -r data.pcap |
TCPDump Parameters
Modifiers
! or not && or and || or or
Examples
udp dst port not 53 UDP not bound for port 53 host 10.0.0.1 && host 10.0.0.2 Traffic between these hosts tcp dst port 80 or 8080 Packets to either TCP port
Protocols
arp ether icmp ip ip6 ppp rarp tcp udp wlan
TCP Flags
tcp-urg tcp-rst tcp-ack tcp-syn tcp-psh tcp-fin
Capture Filter Primitives
[src|dst] host <host> Matches a host as the IP source, destination, or either ether [src|dst] host <ehost> Matches a host as the Ethernet source, destination, or either gateway host <host> Matches packets which used host as a gateway [src|dst] net <network>/<len> Matches packets to or from an endpoint residing in network [tcp|udp] [src|dst] port <port> Matches TCP or UDP packets sent to/from port [tcp|udp] [src|dst] portrange <p1>-<p2> Matches TCP or UDP packets to/from a port in the given range less <length> Matches packets less than or equal to length greater <length> Matches packets greater than or equal to length (ether|ip|ip6) proto <protocol> Matches an Ethernet, IPv4, or IPv6 protocol (ether|ip) broadcast Matches Ethernet or IPv4 broadcasts (ether|ip|ip6) multicast Matches Ethernet, IPv4, or IPv6 multicasts type (mgt|ctl|data) [subtype <subtype>] Matches 802.11 frames based on type and optional subtype vlan [<vlan>] Matches 802.1Q frames, optionally with a VLAN ID of vlan mpls [<label>] Matches MPLS packets, optionally with a label of label <expr> <relop> <expr> Matches packets by an arbitrary expression
Command Line Options
-A Print frame payload in ASCII -c <count> Exit after capturing count packets -D List available interfaces -e Print link-level headers -F <file> Use file as the filter expression -G <n> Rotate the dump file every n seconds -i <iface> Specifies the capture interface -K Don't verify TCP checksums -L List data link types for the interface -n Don't convert addresses to names -p Don't capture in promiscuous mode -q Quick output -r <file> Read packets from file -s <len> Capture up to len bytes per packet -S Print absolute TCP sequence numbers -t Don't print timestamps -v[v[v]] Print more verbose output -w <file> Write captured packets to file -x Print frame payload in hex -X Print frame payload in hex and ASCII -y <type> Specify the data link type
Misc
- In IE, disable HTTP1.1 in Advanced options to see the traffic being sent in HTTP1.0 version. Now you will be able to see traffic in Clear text in wireshark captures. HTTP1.1 uses gzip to compress html, so it is not read in clear text. You will find multiple connections for a single webpage.
- In Wireshark, anyting you see in square brackets - [bla bla] is the wireshar analysis of the information & is not the part of the packet captured.
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