What is nc under centos
NC under centos is the abbreviation of "netcat". It is a network tool that can be used for port scanning, file transfer, etc. nc can also implement listening on any TCP and UDP ports. You can use "yum install nc -y" command to install.
The operating environment of this article: centos 7 system, Dell G3 computer.
What is nc under centos
nc is the abbreviation of netcat tool, a network tool that can be used for port scanning, file transfer and other functions.
The installation on centos is also very simple:
yum install nc -y
nc commonly used functions
realize any TCP /UDP port listening, nc can act as a server to listen to the specified port in TCP or UDP mode
Port scanning, nc can act as a client to initiate a TCP or UDP connection
Transfer files between machines
Network speed test between machines
Generally nc is only used for TCP/UDP Protocol port testing, other functions should be used sparingly!
nc Help Description
# nc --help Ncat 7.50 ( https://nmap.org/ncat ) Usage: ncat [options] [hostname] [port] Options taking a time assume seconds. Append 'ms' for milliseconds, 's' for seconds, 'm' for minutes, or 'h' for hours (e.g. 500ms). -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 -z Zero-I/O mode, report connection status only --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" or "socks5") --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 --ssl-ciphers Cipherlist containing SSL ciphers to use --version Display Ncat's version information and exit
nc Common Cases
TCP Listening Test
nc can be used as the server side 192.168.10.11 to start a tcp monitoring
nc -l 80
Client test method: directly telnet the machine ip port
telnet 192.168.10.11 80
Or: nmap 192.168.10.11 -p 80
UDP listening test
nc starts a udp as the server Monitoring
nc -lu 80
You can see through netstat that the udp protocol has been monitored:
> # netstat -tunlp Active Internet connections (only servers) Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name udp 0 0 0.0.0.0:80 0.0.0.0:* 15401/nc
Recommended tutorial: "centos tutorial"
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