# Using Scapy

### Basics

*BEFORE WE CAN SEND PACKETS, WE MUST FIX IPTABLES! SCAPY BYPASSES THE NORMAL KERNEL PROCEDURES!*

Without this, we will NEVER see the responses from our packets we send! 

```bash
iptables –A OUTPUT –p tcp –tcp-flags RST RST –j DROP
```

There are several basics we can use to create layers in a packet for whatever we would like!

| Command   | Description                       |
| --------- | --------------------------------- |
| `ls()`    | list protocols or variable        |
| `lsc()`   | list supported commands           |
| `send()`  | send layer 3, match all responses |
| `sendp()` | send layer 2, no response         |
| `srp1()`  | send layer 2, match 1 response    |
| `srp()`   | send layer 2, match all responses |

```python
# send and receive [packet], define the return as ans and unans with “_”, print the summary
sr([packet]);
ans, unans = _
ans.summary()

# send a TCP snipe to end the connection, must hit the correct seq from the most recent ack in order to be accepted
send(IP(dst=”192.168.1.200”)/TCP(sport=45089, dport=999, flags=”RA”, seq=3689929657))

i = sniff(filter=”host 192.168.1.100 and icmp”, count=2)
i.summary()
```