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egrep、sed 或 awk 获取活动 dhcp 租约的数量？

tag-icon • tag-icon text-processing freebsd isc-dhcpd
egrep、sed 或 awk 获取活动 dhcp 租约的数量？

假设我有以下 dhcpd.leases 文件：

# The format of this file is documented in the dhcpd.leases(5) manual page.
# This lease file was written by isc-dhcp-4.3.6-P1

# authoring-byte-order entry is generated, DO NOT DELETE
authoring-byte-order little-endian;

lease 10.1.1.108 {
  ...
  starts 3 2020/03/04 08:23:54;
  ends 3 2020/03/04 13:49:03;
  tstp 3 2020/03/04 13:49:03;
  cltt 3 2020/03/04 08:23:54;
  binding state free;
  ...
}
lease 10.1.1.109 {
  ...
  starts 3 2020/03/04 13:43:00;
  ends 3 2020/03/04 13:49:44;
  tstp 3 2020/03/04 13:49:44;
  cltt 3 2020/03/04 13:43:00;
  binding state free;
  ...
}
lease 10.1.2.100 {
  ...
  starts 6 2020/03/28 12:49:45;
  ends 0 2020/03/29 12:49:45;
  tstp 0 2020/03/29 12:49:45;
  cltt 6 2020/03/28 12:49:45;
  binding state active;
  ...
lease 10.1.1.104 {
  ...
  starts 6 2020/03/28 18:53:45;
  ends 0 2020/03/29 18:53:45;
  tstp 0 2020/03/29 18:53:45;
  cltt 6 2020/03/28 18:53:45;
  binding state active;
  ...
}

我想提取每个子网的活动 DHCP 租约数量，本示例如下：

10.1.1.0/24: 1
10.1.2.0/24: 1

现在，我在这里看到了许多有关 dhcpd.leases 文件的问题，但大多数答案都与输出每个 IP 的 Mac 地址有关，这不是我在这里要寻找的。我尝试过的命令的问题是我不知道如何完全排除不活动的租约，不知道如何分割子网，也不知道我应该真正使用哪个工具。

任何帮助，将不胜感激。

这是我尝试过的一些东西，不知道我是否走在正确的道路上，已经使用这些命令玩了几个小时......

egrep "lease|active|\}" /var/dhcpd/var/db/dhcpd.leases
sed -e '/lease/,/active/!d' /var/dhcpd/var/db/dhcpd.leases
awk 'BEGIN{FS="\n"; RS="}";} {print $2}' /var/dhcpd/var/db/dhcpd.leases

然而并没有真正做我想做的事。

注意：我使用的是 pfSense (FreeBSD)。

答案1

好吧，经过更多研究，我决定根据我的目的改编这个 Python 脚本： https://askubuntu.com/questions/219609/how-do-i-show-active-dhcp-leases/553387#553387

另外，我这里的网络拓扑是已知的、固定的并且不会改变，所以我最后做的一些数学计算都考虑到了这一点，但您可以轻松地将其更改为您需要的任何内容。最后，由于所有这些最终都是为了 Checkmk 监控图表脚本，因此输出以 Checkmk 需要解析的方式呈现。无论如何，事不宜迟，这就是：

#!/usr/bin/python
import datetime, bisect

def left(s, amount):
    return s[:amount]

def right(s, amount):
    return s[-amount:]

def mid(s, offset, amount):
    return s[offset:offset+amount]

def parse_timestamp(raw_str):
        tokens = raw_str.split()

        if len(tokens) == 1:
                if tokens[0].lower() == 'never':
                        return 'never';
                else:
                        raise Exception('Parse error in timestamp')
        elif len(tokens) == 3:
                return datetime.datetime.strptime(' '.join(tokens[1:]),'%Y/%m/%d %H:%M:%S')
        else:
                raise Exception('Parse error in timestamp')

def timestamp_is_ge(t1, t2):
        if t1 == 'never':
                return True
        elif t2 == 'never':
                return False
        else:
                return t1 >= t2

def timestamp_is_lt(t1, t2):
        if t1 == 'never':
                return False
        elif t2 == 'never':
                return t1 != 'never'
        else:
                return t1 < t2

def timestamp_is_between(t, tstart, tend):
        return timestamp_is_ge(t, tstart) and timestamp_is_lt(t, tend)

def parse_hardware(raw_str):
        tokens = raw_str.split()

        if len(tokens) == 2:
                return tokens[1]
        else:
                raise Exception('Parse error in hardware')

def strip_endquotes(raw_str):
        return raw_str.strip('"')

def identity(raw_str):
        return raw_str

def parse_binding_state(raw_str):
        tokens = raw_str.split()

        if len(tokens) == 2:
                return tokens[1]
        else:
                raise Exception('Parse error in binding state')

def parse_next_binding_state(raw_str):
        tokens = raw_str.split()

        if len(tokens) == 3:
                return tokens[2]
        else:
                raise Exception('Parse error in next binding state')

def parse_rewind_binding_state(raw_str):
        tokens = raw_str.split()

        if len(tokens) == 3:
                return tokens[2]
        else:
                raise Exception('Parse error in next binding state')

def parse_leases_file(leases_file):
        valid_keys = {
                'starts':               parse_timestamp,
                'ends':                 parse_timestamp,
                'tstp':                 parse_timestamp,
                'tsfp':                 parse_timestamp,
                'atsfp':                parse_timestamp,
                'cltt':                 parse_timestamp,
                'hardware':             parse_hardware,
                'binding':              parse_binding_state,
                'next':                 parse_next_binding_state,
                'rewind':               parse_rewind_binding_state,
                'uid':                  strip_endquotes,
                'client-hostname':      strip_endquotes,
                'option':               identity,
                'set':                  identity,
                'on':                   identity,
                'abandoned':            None,
                'bootp':                None,
                'reserved':             None,
                }

        leases_db = {}
        lease_rec = {}
        in_lease = False
        in_failover = False

        for line in leases_file:
                if line.lstrip().startswith('#'):
                        continue

                tokens = line.split()

                if len(tokens) == 0:
                        continue

                key = tokens[0].lower()

                if key == 'lease':
                        if not in_lease:
                                ip_address = tokens[1]
                                lease_rec = {'ip_address' : ip_address}
                                in_lease = True
                        else:
                                raise Exception('Parse error in leases file')

                elif key == 'failover':
                        in_failover = True
                elif key == '}':
                        if in_lease:
                                for k in valid_keys:
                                        if callable(valid_keys[k]):
                                                lease_rec[k] = lease_rec.get(k, '')
                                        else:
                                                lease_rec[k] = False

                                ip_address = lease_rec['ip_address']

                                if ip_address in leases_db:
                                        leases_db[ip_address].insert(0, lease_rec)
                                else:
                                        leases_db[ip_address] = [lease_rec]

                                lease_rec = {}
                                in_lease = False
                        elif in_failover:
                                in_failover = False
                                continue
                        else:
                                raise Exception('Parse error in leases file')
                elif key in valid_keys:
                        if in_lease:
                                value = line[(line.index(key) + len(key)):]
                                value = value.strip().rstrip(';').rstrip()

                                if callable(valid_keys[key]):
                                        lease_rec[key] = valid_keys[key](value)
                                else:
                                        lease_rec[key] = True
                        else:
                                raise Exception('Parse error in leases file')
                else:
                        if in_lease:
                                raise Exception('Parse error in leases file')
        if in_lease:
                raise Exception('Parse error in leases file')
        return leases_db

def round_timedelta(tdelta):
        return datetime.timedelta(tdelta.days,
                tdelta.seconds + (0 if tdelta.microseconds < 500000 else 1))

def timestamp_now():
        n = datetime.datetime.utcnow()
        return datetime.datetime(n.year, n.month, n.day, n.hour, n.minute,
                n.second + (0 if n.microsecond < 500000 else 1))

def lease_is_active(lease_rec, as_of_ts):
        return timestamp_is_between(as_of_ts, lease_rec['starts'],
                lease_rec['ends'])

def ipv4_to_int(ipv4_addr):
        parts = ipv4_addr.split('.')
        return (int(parts[0]) << 24) + (int(parts[1]) << 16) + \
                (int(parts[2]) << 8) + int(parts[3])

def select_active_leases(leases_db, as_of_ts):
        retarray = []
        sortedarray = []

        for ip_address in leases_db:
                lease_rec = leases_db[ip_address][0]

                if lease_is_active(lease_rec, as_of_ts):
                        ip_as_int = ipv4_to_int(ip_address)
                        insertpos = bisect.bisect(sortedarray, ip_as_int)
                        sortedarray.insert(insertpos, ip_as_int)
                        retarray.insert(insertpos, lease_rec)
        return retarray

myfile = open('/var/dhcpd/var/db/dhcpd.leases', 'r')
leases = parse_leases_file(myfile)
myfile.close()

now = timestamp_now()
report_dataset = select_active_leases(leases, now)
lan_leases = sum(map(lambda x : left(x['ip_address'],7)=='10.1.1.', report_dataset))
wlan_leases = sum(map(lambda x : left(x['ip_address'],8)=='10.20.1.', report_dataset))
wlan_guest_leases = sum(map(lambda x : left(x['ip_address'],8)=='10.20.2.', report_dataset))
wlan_appliance_leases = sum(map(lambda x : left(x['ip_address'],8)=='10.20.3.', report_dataset))

print('0 dhcp_leases lan_leases=' + str(lan_leases) + '|wlan_leases=' + str(wlan_leases) + '|wlan_guest_leases=' + str(wlan_guest_leases) + '|wlan_appliance_leases=' + str(wlan_appliance_leases) + ' ' + str(lan_leases) + ' LAN lease(s), ' + str(wlan_leases) + ' WLAN lease(s), ' + str(wlan_guest_leases) + ' WLAN_GUEST lease(s), ' + str(wlan_appliance_leases) + ' WLAN_APPLIANCE lease(s)')

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