为什么netcat-openbsd中缺少'-e'选项?


Answers:


17

因为该程序有各种版本。

netcat与POSIX中指定的许多其他标准实用程序不同,没有“标准”描述必须支持的选项。您有netcatOpenBSD,FreeBSD,GNU netcat等版本。

对于OpenBSD变体,联机帮助页指出

There is no -c or -e option in this netcat, but you still can execute a
 command after connection being established by redirecting file descriptors.
 Be cautious here because opening a port and let anyone connected execute
 arbitrary command on your site is DANGEROUS. If you really need to do this,
 here is an example:

 On ‘server’ side:

       $ rm -f /tmp/f; mkfifo /tmp/f
       $ cat /tmp/f | /bin/sh -i 2>&1 | nc -l 127.0.0.1 1234 > /tmp/f

 On ‘client’ side:

       $ nc host.example.com 1234
       $ (shell prompt from host.example.com)

 By doing this, you create a fifo at /tmp/f and make nc listen at port 1234
 of address 127.0.0.1 on ‘server’ side, when a ‘client’ establishes a
 connection successfully to that port, /bin/sh gets executed on ‘server’
 side and the shell prompt is given to ‘client’ side.

 When connection is terminated, nc quits as well. Use -k if you want it keep
 listening, but if the command quits this option won't restart it or keep nc
 running. Also don't forget to remove the file descriptor once you don't
 need it anymore:

       $ rm -f /tmp/f

By using our site, you acknowledge that you have read and understand our Cookie Policy and Privacy Policy.
Licensed under cc by-sa 3.0 with attribution required.