% nc -h usage: nc [-46AacCDdEFhklMnOortUuvz] [-K tc] [-b boundif] [-i interval] [-p source_port] [-s source_ip_address] [-w timeout] [-X proxy_version] [-x proxy_address[:port]] [hostname] [port[s]] Command Summary: -4 Use IPv4 -6 Use IPv6 -A Set SO_RECV_ANYIF on socket -a Set SO_AWDL_UNRESTRICTED on socket -b ifbound Bind socket to interface -C Don't use cellular connection -c Send CRLF as line-ending -D Enable the debug socket option -d Detach from stdin -E Don't use expensive interfaces -F Do not use flow advisory (flow adv enabled by default) -G conntimo Connection timeout in seconds -H keepidle Initial idle timeout in seconds -h This help text -I keepintvl Interval for repeating idle timeouts in seconds -i secs Delay interval for lines sent, ports scanned -J keepcnt Number of times to repeat idle timeout -K tclass Specify traffic class -k Keep inbound sockets open for multiple connects -L num_probes Number of probes to send before generating a read timeout event -l Listen mode, for inbound connects -m Set SO_INTCOPROC_ALLOW on socket -N num_probes Number of probes to send before generating a write timeout event -o Issue socket options after connect/bind -n Suppress name/port resolutions -O Use old-style connect instead of connectx -p port Specify local port for remote connects (cannot use with -l) -r Randomize remote ports -s addr Local source address -t Answer TELNET negotiation -U Use UNIX domain socket -u UDP mode -v Verbose -w secs Timeout for connects and final net reads -X proto Proxy protocol: "4", "5" (SOCKS) or "connect" -x addr[:port] Specify proxy address and port -z Zero-I/O mode [used for scanning] Port numbers can be individual or ranges: lo-hi [inclusive]