Serve option contain invalid netcat flag "-q"

[LogicBypass]

Tried to use the serve "-S" option and it gets a netcat error nc: invalid option -- 'q' Netcat version 7.92

I fixed my version of script on line 505

[diego-treitos]

Hello @No0ob1e , the serve option does not support Ncat (yet), it only supports nc.openbsd and nc.traditional. I don't know what linux distribution installs the Ncat binary as nc. It seems quite irregular, but I'd love to know :)

[LogicBypass]

The -q option is supported just in nc.traditional

netcat used as nc preinstalled or installed by default on my machines:

Manjaro 5.10.79-1 on bare metal, netcat installed from pacman don't support "-q" option Kali 5.14.16 vmware, preinstalled netcat used as nc will be from "https://nmap.org/ncat" don't support "-q" option Kali WSL2 installed from apt install the same version as preinstalled in kali from vmware Even nc.openbsd don't support "-q" option: https://man.openbsd.org/nc.1

Let's find the usage for the -q option in this script: -q seconds - Are used to wait the specified amount of time after the end of the received file from a stdin and then to close the connection. "To make sure that the file is fully received and it's not a connection issue"

Now let's take a look at the syntax in the script nc -l -q0 -p "$port" < "$0" >/dev/null -q is set to 0 so it's doesn't have any useful usage than creating errors on different versions of netcat installed on users machines, or I may be wrong :)

Serve options it's a really useful feature and it's not a big deal to change it for my usage, but I want to share my experience to help to make it easy to use for other people :)

[diego-treitos]

Hi again @No0ob1e , first of all thank you for taking your time looking into this.

I mostly use debian systems and there, the nc.openbsd has the -q option. I only tested from debian-like systems...😇

$ nc.openbsd -h
OpenBSD netcat (Debian patchlevel 1.217-3)
usage: nc [-46CDdFhklNnrStUuvZz] [-I length] [-i interval] [-M ttl]
      [-m minttl] [-O length] [-P proxy_username] [-p source_port]
      [-q seconds] [-s sourceaddr] [-T keyword] [-V rtable] [-W recvlimit]
      [-w timeout] [-X proxy_protocol] [-x proxy_address[:port]]
      [destination] [port]
    Command Summary:
        -4      Use IPv4
        -6      Use IPv6
        -b      Allow broadcast
        -C      Send CRLF as line-ending
        -D      Enable the debug socket option
        -d      Detach from stdin
        -F      Pass socket fd
        -h      This help text
        -I length   TCP receive buffer length
        -i interval Delay interval for lines sent, ports scanned
        -k      Keep inbound sockets open for multiple connects
        -l      Listen mode, for inbound connects
        -M ttl      Outgoing TTL / Hop Limit
        -m minttl   Minimum incoming TTL / Hop Limit
        -N      Shutdown the network socket after EOF on stdin
        -n      Suppress name/port resolutions
        -O length   TCP send buffer length
        -P proxyuser    Username for proxy authentication
        -p port     Specify local port for remote connects
        -q secs     quit after EOF on stdin and delay of secs
        -r      Randomize remote ports
        -S      Enable the TCP MD5 signature option
        -s sourceaddr   Local source address
        -T keyword  TOS value
        -t      Answer TELNET negotiation
        -U      Use UNIX domain socket
        -u      UDP mode
        -V rtable   Specify alternate routing table
        -v      Verbose
        -W recvlimit    Terminate after receiving a number of packets
        -w timeout  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      DCCP mode
        -z      Zero-I/O mode [used for scanning]
    Port numbers can be individual or ranges: lo-hi [inclusive]

The purpose of the -q0 is so the netcat that sends the script quits after EOF. For nc.openbsd we have -N, but nc.traditional doesn't have it so... as both nc.openbsd and nc.traditional had -q (at least in the systems I tested), I used -q.

I think I already have a patch for the problem.

[diego-treitos]

Alright, I have just released version 3.8, which should solve the problem. This version should support nc.openbsd, nc.traditional and ncat.

I am closing the ticket, but feel free to reopen if it wasn't properly fixed.