Sometimes Net::SSH2 can't read() from channel?

Apr 9, 2008 9:20 pm

Richard Fernandez

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Hi folks,
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I have a test script ( mostly ripped from a posting I found on a CPAN
forum) which uses Net::SSH2 to run a `who' command on a remote server.
The script works fine for most servers, but I have a few boxes where,
despite being able to login, I get no output.=20
Anyone have any ideas why this might be happening?
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TIA
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richf
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#!/usr/local/bin/perl
use warnings;
use strict;
use Net::SSH2;
use Getopt::Std;
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our($opt_s, $opt_p);
getopts('p:s:');
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my $passwd =3D $opt_p ? $opt_p : usage();
my $server =3D $opt_s ? $opt_s : usage();
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print "Connecting to $server...\n";
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my $ssh2 =3D Net::SSH2->new();
$ssh2->debug(1);
$ssh2->connect($server) or die "Can't connect to $server\n";
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if( $ssh2->auth_password('root', $passwd)) {
my $chan =3D $ssh2->channel();
my $returnval =3D $chan->exec('who') or die "Couldn't exec
'who'\n";
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my($len, $buff);
while($len =3D $chan->read($buff, 1024)) {
print $buff;
}
$chan->close;
}
else {
print "Invalid username or password $!\n";
}
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sub usage {
die "usage: $0 -s <server> -p <passwd>\n";
}

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[richf@richx:/home/richf/bin] ./mytest.pl -s server1 -p passwd
Connecting to server1...
libssh2_channel_open_ex(ss->session, pv_channel_type, len_channel_type,
window_size, packet_size, 0L , 0 ) -> 0x89bb0600
Net::SSH2::Channel::read(size =3D 1024, ext =3D 0)
- read 44 bytes
- read 0 bytes
- read 44 total
root tty1 Mar 9 10:55 =20
Net::SSH2::Channel::read(size =3D 1024, ext =3D 0)
- read 0 bytes
- read 0 total
Net::SSH2::Channel::DESTROY
Net::SSH2::DESTROY object 0x867c4c80
[richf@richx:/home/richf/bin]=20
[richf@richx:/home/richf/bin]=20
[richf@richx:/home/richf/bin] ./mytest.pl -s server2 -p passwd
Connecting to server2...
libssh2_channel_open_ex(ss->session, pv_channel_type, len_channel_type,
window_size, packet_size, 0L , 0 ) -> 0x8241e600
Net::SSH2::Channel::read(size =3D 1024, ext =3D 0)
- read 0 bytes
- read 0 total
Net::SSH2::Channel::DESTROY
Net::SSH2::DESTROY object 0x81245b40

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