使用F5内置命令：nc（NetCat）

NetCat，在网络工具中有“瑞士军刀”美誉，功能非常强大，测试udp只是其中的一个功能变通。在安全领域nc常用来端口监听转发，用的比较多的也是windows版的NC，在运维中需要常用到linux上的nc，而一般linux会默认集成这个命令，根据不同系统命令不同，有的为“nc”，有的为“netcat”，大家可以根据实际系统尝试下。

接下来进行连接性测试

# 使用 nc -uv $ip $port 命令，输入多次回车没有出现异常表示连接正常
#正常示例：
[root@bigip1:Active:Standalone] config # nc -uv 114.114.114.114 53
Ncat: Version 6.40 ( http://nmap.org/ncat )
Ncat: Connected to 114.114.114.114:53.

# 使用 nc -uv $ip $port 命令，输入多次回车出现异常表示连接端口失败
#失败示例：
[root@bigip1:Active:Standalone] config # nc -uv 114.114.114.114 535
Ncat: Version 6.40 ( http://nmap.org/ncat )
Ncat: Connected to 114.114.114.114:535.

Ncat: Connection refused.

其他参数如下所示：

  -4                         Use IPv4 only
  -6                         Use IPv6 only
  -U, --unixsock             Use Unix domain sockets only
  -C, --crlf                 Use CRLF for EOL sequence
  -c, --sh-exec <command>    Executes the given command via /bin/sh
  -e, --exec <command>       Executes the given command
      --lua-exec <filename>  Executes the given Lua script
  -g hop1[,hop2,...]         Loose source routing hop points (8 max)
  -G <n>                     Loose source routing hop pointer (4, 8, 12, ...)
  -m, --max-conns <n>        Maximum <n> simultaneous connections
  -h, --help                 Display this help screen
  -d, --delay <time>         Wait between read/writes
  -o, --output <filename>    Dump session data to a file
  -x, --hex-dump <filename>  Dump session data as hex to a file
  -i, --idle-timeout <time>  Idle read/write timeout
  -p, --source-port port     Specify source port to use
  -s, --source addr          Specify source address to use (doesn't affect -l)
  -l, --listen               Bind and listen for incoming connections
  -k, --keep-open            Accept multiple connections in listen mode
  -n, --nodns                Do not resolve hostnames via DNS
  -t, --telnet               Answer Telnet negotiations
  -u, --udp                  Use UDP instead of default TCP
      --sctp                 Use SCTP instead of default TCP
  -v, --verbose              Set verbosity level (can be used several times)
  -w, --wait <time>          Connect timeout
      --append-output        Append rather than clobber specified output files
      --send-only            Only send data, ignoring received; quit on EOF
      --recv-only            Only receive data, never send anything
      --allow                Allow only given hosts to connect to Ncat
      --allowfile            A file of hosts allowed to connect to Ncat
      --deny                 Deny given hosts from connecting to Ncat
      --denyfile             A file of hosts denied from connecting to Ncat
      --broker               Enable Ncat's connection brokering mode
      --chat                 Start a simple Ncat chat server
      --proxy <addr[:port]>  Specify address of host to proxy through
      --proxy-type <type>    Specify proxy type ("http" or "socks4")
      --proxy-auth <auth>    Authenticate with HTTP or SOCKS proxy server
      --ssl                  Connect or listen with SSL
      --ssl-cert             Specify SSL certificate file (PEM) for listening
      --ssl-key              Specify SSL private key (PEM) for listening
      --ssl-verify           Verify trust and domain name of certificates
      --ssl-trustfile        PEM file containing trusted SSL certificates
      --version              Display Ncat's version information and exit