前言：
之前用arp统计过某网段下的ip，但是有可能统计不全。网络管理平台又不允许登录。想要知道当前的ip占用情况，可以使用fping
fping命令类似于ping，但比ping更强大。与ping需要等待某一主机连接超时或发回反馈信息不同，fping在给一个主机发送完数据包后，马上给下一个主机发送数据包，实现多主机同时ping。同时，fping还可以在命令行中指定要ping的主机数量范围。
但是当某台主机或者交换机的网络策略禁用ICMP或者禁止ping包的时候，那就无法通过此方法来获取局域网中被占用的具体ip
使用方式：
ping指定的多个IP：
fping 192.168.3.1 192.168.3.12 192.168.3.16 2>/dev/null
ping整个网段：
fping -g 192.168.3.0/24 2>/dev/null
ping整个网段，只显示存活的主机：
fping -ag 192.168.3.0/24 2>/dev/null
ping某一段IP：
fping -ag 192.168.0.5 192.168.0.130 2>/dev/null
ping的具体选项目
Usage: fping [options] [targets...]
Probing options:
-4, --ipv4 only ping IPv4 addresses
-6, --ipv6 only ping IPv6 addresses
-b, --size=BYTES amount of ping data to send, in bytes (default: 56)
-B, --backoff=N set exponential backoff factor to N (default: 1.5)
-c, --count=N count mode: send N pings to each target
-f, --file=FILE read list of targets from a file ( - means stdin)
-g, --generate generate target list (only if no -f specified)
(give start and end IP in the target list, or a CIDR address)
(ex. fping -g 192.168.1.0 192.168.1.255 or fping -g 192.168.1.0/24)
-H, --ttl=N set the IP TTL value (Time To Live hops)
-I, --iface=IFACE bind to a particular interface
-l, --loop loop mode: send pings forever
-m, --all use all IPs of provided hostnames (e.g. IPv4 and IPv6), use with -A
-M, --dontfrag set the Don't Fragment flag
-O, --tos=N set the type of service (tos) flag on the ICMP packets
-p, --period=MSEC interval between ping packets to one target (in ms)
(in loop and count modes, default: 1000 ms)
-r, --retry=N number of retries (default: 3)
-R, --random random packet data (to foil link data compression)
-S, --src=IP set source address
-t, --timeout=MSEC individual target initial timeout (default: 500 ms,
except with -l/-c/-C, where it's the -p period up to 2000 ms)
Output options:
-a, --alive show targets that are alive
-A, --addr show targets by address
-C, --vcount=N same as -c, report results in verbose format
-D, --timestamp print timestamp before each output line
-e, --elapsed show elapsed time on return packets
-i, --interval=MSEC interval between sending ping packets (default: 10 ms)
-n, --name show targets by name (-d is equivalent)
-N, --netdata output compatible for netdata (-l -Q are required)
-o, --outage show the accumulated outage time (lost packets * packet interval)
-q, --quiet quiet (don't show per-target/per-ping results)
-Q, --squiet=SECS same as -q, but show summary every n seconds
-s, --stats print final stats
-u, --unreach show targets that are unreachable
-v, --version show version
-x, --reachable=N shows if >=N hosts are reachable or not
