10.2.177.170 Tue Jun 19 03:30:55 CDT 2018
10.2.177.170 Tue Jun 19 03:31:03 CDT 2018
10.2.177.170 Tue Jun 19 03:31:04 CDT 2018
10.2.177.170 Tue Jun 19 03:32:04 CDT 2018
10.2.177.170 Tue Jun 19 03:33:04 CDT 2018

2018:19:03:32:04

10.1.177.170 Tue Jun 19 03:30:55 CDT 2018
10.1.177.170 Tue Jun 19 03:31:03 CDT 2018
10.1.177.170 Tue Jun 19 03:31:04 CDT 2018
10.1.177.170 Tue Jun 19 03:32:04 CDT 2018

x1 = line.split()[0]
IndexError: list index out of range

def run():

    f = open('firewall.log', 'r')
    lnumber = dict()
    for num,line in enumerate(f,1):
        x1 = line.split()[0]
        log_day  = line.split()[3]
        log_time = line.split()[4]
        log_year = line.split()[6]
        if x1 in lnumber:
            lnumber[x1].append((log_year + ":" + log_day + ":" + log_time))
        else:
            lnumber[x1] = [(num,log_time)]

    if x1 in lnumber and len(lnumber.get(x1,None)) > 2:

        # if there are less than 3 lines in document, this will fail

        line_time = (lnumber[x1][-3].__str__())
        print(line_time)
    else:
        print('nothing')
    f.close

run()