테스트 환경 : CentOS7, Amazon Linux 2
위와 같은 환경에서 nc 명령어를 사용했더니 -bash: nc: command not found 에러가 발생했다.
즉, nc 패키지가 리눅스에 설지되지 않아서 명령어를 찾을 수 없다는 에러가 발생한 것이다.
그래서 nc 패키지를 설치 하기 위한 명령어를 구글에 계속 검색했으나 확실한 명령어를 찾을 수 없어 많은 시간을 소비했다.
혹시나 나와 같은 분들이 계실까봐 조금이나마 도움이 되시라고 글을 포스팅하게 되었다.
이 명령어를 통해 설치하면 nc 명령어를 사용할 수 있다. sudo yum install -y nmap-ncat
참고로 nmap은 Network Map을 뜻하며 네트워크에 연결되어 있는 호스트들의 정보를 파악 하는 도구이다.
ncat은 Network cat을 뜻하며 네트워크를 입출력 할 수 있는 도구라고 생각하면 된다.
nc 명령어에서 사용할 수 있는 옵션은 아래와 같다.
# 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