端口扫描的目的是识别目标系统中哪些端口是开启状态，哪些服务可以使用。比如FTP/SSH/TELNET/打印服务/web服务等等。计算机系统中共有65536个端口，因此连接这些端口并扫描出可用的端口就变的有意义了。
kali的网络默认是 设备未托管状态，因此需要开启。开启方法：
修改/etc/NetworkManager/下的NetworkManger.conf文件，
managed = false修改为true
重启机子
root@walfred:~# fping -h Usage: fping [options] [targets...] -a show targets that are alive -A show targets by address -b n amount of ping data to send, in bytes (default 56) -B f set exponential backoff factor to f -c n count of pings to send to each target (default 1) -C n same as -c, report results in verbose format -e show elapsed time on return packets -f file read list of targets from a file ( - means stdin) (only if no -g specified) -g generate target list (only if no -f specified) (specify the start and end IP in the target list, or supply a IP netmask) (ex. fping -g 192.168.1.0 192.168.1.255 or fping -g 192.168.1.0/24) -H n Set the IP TTL value (Time To Live hops) -i n interval between sending ping packets (in millisec) (default 25) -l loop sending pings forever -m ping multiple interfaces on target host -n show targets by name (-d is equivalent) -p n interval between ping packets to one target (in millisec) (in looping and counting modes, default 1000) -q quiet (don't show per-target/per-ping results) -Q n same as -q, but show summary every n seconds -r n number of retries (default 3) -s print final stats -I if bind to a particular interface -S addr set source address -t n individual target initial timeout (in millisec) (default 500) -T n ignored (for compatibility with fping 2.4) -u show targets that are unreachable -O n set the type of service (tos) flag on the ICMP packets -v show version targets list of targets to check (if no -f specified)
使用方法：
root@walfred:~# nmap -h
Nmap 6.47 ( http://nmap.org )
Usage: nmap [Scan Type(s)] [Options] {target specification}
TARGET SPECIFICATION:
Can pass hostnames, IP addresses, networks, etc.
Ex: scanme.nmap.org, microsoft.com/24, 192.168.0.1; 10.0.0-255.1-254
-iL <inputfilename>: Input from list of hosts/networks
-iR <num hosts>: Choose random targets
--exclude <host1[,host2][,host3],...>: Exclude hosts/networks
--excludefile <exclude_file>: Exclude list from file
HOST DISCOVERY: 主机网络发现功能
-sL: List Scan - simply list targets to scan
-sn: Ping Scan - disable port scan
-Pn: Treat all hosts as online -- skip host discovery 禁止网络发现功能，认为所有主机在线
-PS/PA/PU/PY[portlist]: TCP SYN/ACK, UDP or SCTP discovery to given ports
-PE/PP/PM: ICMP echo, timestamp, and netmask request discovery probes
-PO[protocol list]: IP Protocol Ping
-n/-R: Never do DNS resolution/Always resolve [default: sometimes]
--dns-servers <serv1[,serv2],...>: Specify custom DNS servers
--system-dns: Use OS's DNS resolver
--traceroute: Trace hop path to each host
SCAN TECHNIQUES:
-sS/sT/sA/sW/sM: TCP SYN/Connect()/ACK/Window/Maimon scans SYN/TCP/ACK/windown/conn扫描参数
-sU: UDP Scan UDP扫描参数指定
-sN/sF/sX: TCP Null, FIN, and Xmas scans NULL/FIN/xmas扫描
--scanflags <flags>: Customize TCP scan flags
-sI <zombie host[:probeport]>: Idle scan
-sY/sZ: SCTP INIT/COOKIE-ECHO scans
-sO: IP protocol scan
-b <FTP relay host>: FTP bounce scan
PORT SPECIFICATION AND SCAN ORDER:
-p <port ranges>: Only scan specified ports
Ex: -p22; -p1-65535; -p U:53,111,137,T:21-25,80,139,8080,S:9
-F: Fast mode - Scan fewer ports than the default scan
-r: Scan ports consecutively - don't randomize
--top-ports <number>: Scan <number> most common ports
--port-ratio <ratio>: Scan ports more common than <ratio>
SERVICE/VERSION DETECTION:
-sV: Probe open ports to determine service/version info
--version-intensity <level>: Set from 0 (light) to 9 (try all probes)
--version-light: Limit to most likely probes (intensity 2)
--version-all: Try every single probe (intensity 9)
--version-trace: Show detailed version scan activity (for debugging)
SCRIPT SCAN:
-sC: equivalent to --script=default
--script=<Lua scripts>: <Lua scripts> is a comma separated list of
directories, script-files or script-categories
--script-args=<n1=v1,[n2=v2,...]>: provide arguments to scripts
--script-args-file=filename: provide NSE script args in a file
--script-trace: Show all data sent and received
--script-updatedb: Update the script database.
--script-help=<Lua scripts>: Show help about scripts.
<Lua scripts> is a comma-separated list of script-files or
script-categories.
OS DETECTION:
-O: Enable OS detection
--osscan-limit: Limit OS detection to promising targets
--osscan-guess: Guess OS more aggressively
TIMING AND PERFORMANCE:
Options which take <time> are in seconds, or append 'ms' (milliseconds),
's' (seconds), 'm' (minutes), or 'h' (hours) to the value (e.g. 30m).
-T<0-5>: Set timing template (higher is faster)
--min-hostgroup/max-hostgroup <size>: Parallel host scan group sizes
--min-parallelism/max-parallelism <numprobes>: Probe parallelization
--min-rtt-timeout/max-rtt-timeout/initial-rtt-timeout <time>: Specifies
probe round trip time.
--max-retries <tries>: Caps number of port scan probe retransmissions.
--host-timeout <time>: Give up on target after this long
--scan-delay/--max-scan-delay <time>: Adjust delay between probes
--min-rate <number>: Send packets no slower than <number> per second
--max-rate <number>: Send packets no faster than <number> per second
FIREWALL/IDS EVASION AND SPOOFING:
-f; --mtu <val>: fragment packets (optionally w/given MTU)
-D <decoy1,decoy2[,ME],...>: Cloak a scan with decoys
-S <IP_Address>: Spoof source address
-e <iface>: Use specified interface
-g/--source-port <portnum>: Use given port number
--proxies <url1,[url2],...>: Relay connections through HTTP/SOCKS4 proxies
--data-length <num>: Append random data to sent packets
--ip-options <options>: Send packets with specified ip options
--ttl <val>: Set IP time-to-live field
--spoof-mac <mac address/prefix/vendor name>: Spoof your MAC address
--badsum: Send packets with a bogus TCP/UDP/SCTP checksum
OUTPUT:
-oN/-oX/-oS/-oG <file>: Output scan in normal, XML, s|<rIpt kIddi3,
and Grepable format, respectively, to the given filename.
-oA <basename>: Output in the three major formats at once
-v: Increase verbosity level (use -vv or more for greater effect)
-d: Increase debugging level (use -dd or more for greater effect)
--reason: Display the reason a port is in a particular state
--open: Only show open (or possibly open) ports
--packet-trace: Show all packets sent and received
--iflist: Print host interfaces and routes (for debugging)
--log-errors: Log errors/warnings to the normal-format output file
--append-output: Append to rather than clobber specified output files
--resume <filename>: Resume an aborted scan
--stylesheet <path/URL>: XSL stylesheet to transform XML output to HTML
--webxml: Reference stylesheet from Nmap.Org for more portable XML
--no-stylesheet: Prevent associating of XSL stylesheet w/XML output
MISC:
-6: Enable IPv6 scanning
-A: Enable OS detection, version detection, script scanning, and traceroute
--datadir <dirname>: Specify custom Nmap data file location
--send-eth/--send-ip: Send using raw ethernet frames or IP packets
--privileged: Assume that the user is fully privileged
--unprivileged: Assume the user lacks raw socket privileges
-V: Print version number
-h: Print this help summary page.
EXAMPLES:
nmap -v -A scanme.nmap.org
nmap -v -sn 192.168.0.0/16 10.0.0.0/8
nmap -v -iR 10000 -Pn -p 80
SEE THE MAN PAGE (http://nmap.org/book/man.html) FOR MORE OPTIONS AND EXAMPLES
3.1Nmap执行TCP扫描
-sT 对TCP进行扫描
-p- 对所有端口扫描
-PN 禁用Nmap网络发现功能，假定所有系统都是活动的
root@walfred:~# nmap -sT -p- -PN 192.168.115.1 Starting Nmap 6.47 ( http://nmap.org ) at 2014-10-23 20:38 CST Stats: 0:12:34 elapsed; 0 hosts completed (1 up), 1 undergoing Connect Scan Connect Scan Timing: About 90.20% done; ETC: 20:51 (0:01:22 remaining) Stats: 0:16:16 elapsed; 0 hosts completed (1 up), 1 undergoing Connect Scan Connect Scan Timing: About 94.41% done; ETC: 20:55 (0:00:58 remaining) Nmap scan report for 192.168.115.1 Host is up (0.0022s latency). Not shown: 65533 closed ports PORT STATE SERVICE 23/tcp open telnet 80/tcp open http Nmap done: 1 IP address (1 host up) scanned in 1274.21 seconds
3.2Nmap执行UDP扫描
扫描udp也是有理由的，比如一些基于udp的服务，SNMP、TFTP、DHCP、DNS等等root@walfred:~# nmap -sU 192.168.115.188 Starting Nmap 6.47 ( http://nmap.org ) at 2014-10-23 20:21 CST Nmap scan report for 192.168.115.188 Host is up (0.00069s latency). Not shown: 994 closed ports PORT STATE SERVICE 137/udp open netbios-ns 138/udp open|filtered netbios-dgm 500/udp open|filtered isakmp 1900/udp open|filtered upnp 4500/udp open|filtered nat-t-ike 5355/udp open|filtered llmnr MAC Address: xxxxxxxxxxxxxx (Universal Global Scientific Industrial Co.) Nmap done: 1 IP address (1 host up) scanned in 974.78 seconds
3.3Nmap执行SYN扫描
nmap默认就是这种方式。这种方式要比TCP扫描快，因为只执行三次握手的前两次。也不会造成拒绝服务攻击root@walfred:~# nmap -sS -p- -PN 192.168.115.1 Starting Nmap 6.47 ( http://nmap.org ) at 2014-10-23 20:26 CST Nmap scan report for 192.168.115.1 Host is up (0.0020s latency). Not shown: 65533 closed ports PORT STATE SERVICE 23/tcp open telnet 80/tcp open http MAC Address: xxxxxxxxxxxxxx (Digital China (Shanghai) Networks) Nmap done: 1 IP address (1 host up) scanned in 368.52 seconds哇偶，竟然开放了telnet....3.3Nmap执行Xmas扫描
RFC文档描述了系统的技术细节，因此如果得到RFC文档，那么就可能找到系统的漏洞，xmas和null扫描的目的正是基于这一原因。
如果系统遵循了TCP RFC文档，那么不用完成连接，仅仅在发起连接的时候，namp就可以判断出目标系统的状态。
但是一般xmas针对unix或者linux系统比较有效。
root@walfred:~# nmap -sX -p- -Pn 192.168.115.1 Starting Nmap 6.47 ( http://nmap.org ) at 2014-10-23 20:42 CST Nmap scan report for 192.168.115.1 Host is up (0.0029s latency). Not shown: 65533 closed ports PORT STATE SERVICE 23/tcp open|filtered telnet 80/tcp open|filtered http MAC Address: XXXXXXXXXXXXX (Digital China (Shanghai) Networks) Nmap done: 1 IP address (1 host up) scanned in 382.91 seconds
3.4Nmap执行Null
root@walfred:~# nmap -sN -p- -Pn 192.168.115.1 Starting Nmap 6.47 ( http://nmap.org ) at 2014-10-23 20:49 CST Stats: 0:04:54 elapsed; 0 hosts completed (1 up), 1 undergoing NULL Scan NULL Scan Timing: About 78.30% done; ETC: 20:55 (0:01:20 remaining) Nmap scan report for 192.168.115.1 Host is up (0.0018s latency). Not shown: 65533 closed ports PORT STATE SERVICE 23/tcp open|filtered telnet 80/tcp open|filtered http MAC Address: XXXXXXXXXXXXX (Digital China (Shanghai) Networks) Nmap done: 1 IP address (1 host up) scanned in 376.37 seconds
原文地址：http://blog.csdn.net/wang_walfred/article/details/40402311
