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ncat usage
From: Dave Henderson <dhenderson () digital-pipe com>
Date: Mon, 07 May 2012 15:34:06 -0400

Good afternoon gang! I'm working on a project that currently uses Berkley's netcat (nc), however, during some research I stumbled on ncat. I can see that it's much more comprehensive so I'd like to make the switch to using it instead, but I can't seem to get it working right. The project is basically a bash version of a web server. I'll post the working code below. Any help would greatly be appreciated!

Thanks,
Dave



while (( 1 == 1 )); do # causes an infinite loop for processing requests #nc -Cl $sOPTS "$iPORT" < "$SI" > "$SO" 2>>/tmp/debug.txt & # netcat-openbsd - DEBUGGING ERRORS/MESSAGES nc -Cl $sOPTS "$iPORT" < "$SI" > "$SO" & # netcat-openbsd #ncat $sOPTS -vvv -C -l 127.0.0.1 $iPORT < "$SI" > "$SO" & # ncat

trap exitGraceful SIGINT # traps ctrl-C to exit this script
    head -n 1 "$SO" | procRequest > "$SI"
    trap - SIGINT
done



Basically the above 'while' loop cycles for every request submitted causing netcat to process the request and then restart. Currently the webpages are being served using nc, but when I switch to ncat, I get the following (verbose) output at the command prompt, but no webpage ever comes up in the browser:

Ncat: Version 5.21 ( http://nmap.org/ncat )
Ncat: Listening on 127.0.0.1:80
NCAT DEBUG: Initialized fdlist with 102 maxfds
NCAT DEBUG: Added fd 3 to list, nfds 1, maxfd 3
NCAT DEBUG: Added fd 0 to list, nfds 2, maxfd 3
NCAT DEBUG: Initialized fdlist with 100 maxfds
NCAT DEBUG: selecting, fdmax 3
NCAT DEBUG: select returned 1 fds ready
NCAT DEBUG: fd 3 is ready
Ncat: Connection from 127.0.0.1.
NCAT DEBUG: Added fd 4 to list, nfds 3, maxfd 4
NCAT DEBUG: Added fd 4 to list, nfds 1, maxfd 4
NCAT DEBUG: selecting, fdmax 4
NCAT DEBUG: select returned 1 fds ready
NCAT DEBUG: fd 4 is ready
NCAT DEBUG: selecting, fdmax 4
Mon May 7 19:22:41 UTC 2012 INFO Executing ./modules/cdb/default.sh script
NCAT DEBUG: select returned 1 fds ready
NCAT DEBUG: fd 0 is ready
NCAT DEBUG: selecting, fdmax 4
NCAT DEBUG: select returned 1 fds ready
NCAT DEBUG: fd 0 is ready
NCAT DEBUG: selecting, fdmax 4
NCAT DEBUG: select returned 1 fds ready
NCAT DEBUG: fd 0 is ready
NCAT DEBUG: selecting, fdmax 4
NCAT DEBUG: select returned 1 fds ready
NCAT DEBUG: fd 0 is ready
NCAT DEBUG: selecting, fdmax 4
NCAT DEBUG: select returned 1 fds ready
NCAT DEBUG: fd 0 is ready
NCAT DEBUG: selecting, fdmax 4
NCAT DEBUG: select returned 1 fds ready
NCAT DEBUG: fd 0 is ready
NCAT DEBUG: selecting, fdmax 4
NCAT DEBUG: select returned 1 fds ready
NCAT DEBUG: fd 0 is ready
NCAT DEBUG: selecting, fdmax 4
NCAT DEBUG: select returned 1 fds ready
NCAT DEBUG: fd 0 is ready
NCAT DEBUG: selecting, fdmax 4
NCAT DEBUG: select returned 1 fds ready
NCAT DEBUG: fd 0 is ready
NCAT DEBUG: selecting, fdmax 4
NCAT DEBUG: select returned 1 fds ready
NCAT DEBUG: fd 0 is ready
NCAT DEBUG: selecting, fdmax 4
NCAT DEBUG: select returned 1 fds ready
NCAT DEBUG: fd 0 is ready
NCAT DEBUG: selecting, fdmax 4
NCAT DEBUG: select returned 1 fds ready
NCAT DEBUG: fd 0 is ready
NCAT DEBUG: selecting, fdmax 4
NCAT DEBUG: select returned 1 fds ready
NCAT DEBUG: fd 0 is ready
NCAT DEBUG: selecting, fdmax 4
NCAT DEBUG: select returned 1 fds ready
NCAT DEBUG: fd 0 is ready
NCAT DEBUG: selecting, fdmax 4
NCAT DEBUG: select returned 1 fds ready
NCAT DEBUG: fd 0 is ready
NCAT DEBUG: selecting, fdmax 4
NCAT DEBUG: select returned 1 fds ready
NCAT DEBUG: fd 0 is ready
NCAT DEBUG: selecting, fdmax 4
NCAT DEBUG: select returned 1 fds ready
NCAT DEBUG: fd 0 is ready
NCAT DEBUG: EOF on stdin
NCAT DEBUG: selecting, fdmax 4


It looks like the correct script gets called (./modules/cdb/default.sh), but again, nothing comes back to the browser. Any ideas about what might be happening? Perhaps something is going wrong in the I/O redirection... Thanks for any help!

Dave

PS.
Is there a way to have ncat remain running (-k) and simulate EOF so that the connection to the script and browser is closed correctly?
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