Extracting source and destination IP to check if the server has become inoperative after attack

Question

from scapy.all import *
from collections import deque

def print_attack_measure(pcap_file):
    plist = rdpcap(pcap_file)
    server_ip = "192.168.1.5"
    n = 300
    d = deque(maxlen=n)

    # If you want source/destination IP addresses
    getsrcdst = lambda x:(x.src,x.dst)
    # If you want MAC addresses
    getmacs   = lambda x:(x.addr1, x.addr2, x.addr3)

    def filterpackets(ip):
        for p in plist:
            try:
                c = getsrcdst(p)
                if(ip in c[0]):
                    # server IP is source IP of packet
                    yield -1
                if(ip in c[1]):
                    # server IP is destination IP of packet
                    yield 1
            except AttributeError:
                pass

print("This prints a measure of packets received to packets sent, using a moving average of %d packets."%(n))
print("0 indicates a perfect balance of sent-received.")
print("+1 indicates all packets are sent to the server.")
print("-1 indicates all packets are sent by the server.")
print("A larger positive number indicates an unresponsive server.")

count = 0
for pack in filterpackets(server_ip):
    d.append(pack)
    count += 1
    if(count>n):
        print("%0.4f"%(sum(d)/(1.0*n)))


print_attack_measure("1.pcap") # sem ataques
print_attack_measure("2.pcap") # com ataques

Lambda function extracts the source and destination Ips from the package.

package sent to server : +1 package sent by server : -1

The code is in http://pastebin.com/DFEnZzqn

Error: http://imgur.com/a/KC87V

Any suggestions?