CODEWITHSUNDEEP
linuxbashsystemnetcat
user787935
user787935

Reputation: 141

Emulating netcat -e

How can I emulate netcat -e with a version of netcat that does not have the -e option ?

I need to trigger a command remotely. I can do it with netcat - without -e:

#!/bin/bash

netcat -l 8080 ; myCommand.sh

That would do the trick, but I would like to reply to the client depending on the success or failure of the command (to have a kind of REST - like interface).

How could I do that ?

Thanks!

Upvotes: 14

Views: 15305

Answers (2)

Jocko
Jocko

Reputation: 141

mkfifo foo
nc -lk 2600 0<foo | /bin/bash 1>foo

Then just nc servername 2600 and ./script.sh

kill the client with ctrl+c

Upvotes: 14

sehe
sehe

Reputation: 393709

The best way is to switch to the version of netcat that does support it. On Debian/Ubuntu IIRC correctly you should use netcat traditional, not netcat openbsd:

 sudo apt-get install netcat-traditional # netcat-openbsd

You will have the option of specifying explicitely which version you require: 

 nc.traditional server 6767 -e myscript.sh

 nc.openbsd -l 6767

(note the subtle differences in option usage). As you can see (below) nc.traditional can be run as a standalone binary, depending on only libc and linux itself, so if you don't have installation permissions, you should be able to just drop the standalone binary somewhere (a filesystem with exec permission of course) and run it like

 /home/user/bin/mynetcat server 6767 -e myscript.sh

HTH

$ ldd `which nc.{traditional,openbsd}`

/bin/nc.traditional:
    linux-gate.so.1 =>  (0xb7888000)
    libc.so.6 => /lib/libc.so.6 (0xb7709000)
    /lib/ld-linux.so.2 (0xb7889000)
/bin/nc.openbsd:
    linux-gate.so.1 =>  (0xb77d0000)
    libglib-2.0.so.0 => /lib/libglib-2.0.so.0 (0xb76df000)
    libc.so.6 => /lib/libc.so.6 (0xb7582000)
    libpcre.so.3 => /lib/libpcre.so.3 (0xb754c000)
    /lib/ld-linux.so.2 (0xb77d1000)

Upvotes: 5

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