waytoperl has asked for the wisdom of the Perl Monks concerning the following question:

Hi

Using Net::OpenSSH to SSH into a remote ox and getting "Pseudo-terminal will not be allocated because stdin is not a terminal." error. Can anyyone provide insights how to solve this issue. Thanks. 

#!/usr/bin/perl
  
use strict;
use warnings;
use Net::OpenSSH; 

my $user = "";
my $passwd = "";
my $host = "";

my @cmd = "show clock";
my @quitcmd = "exit";
 
my $ssh = Net::OpenSSH->new("$host", user => "$user", passwd => "$pass
+wd", timeout => 90 );
$ssh->error and
   die "Couldn't establish SSH connection: ". $ssh->error;
 
my @output = $ssh->capture({stdin_data => "@cmd\n@quitcmd\n"});
$ssh->error and
   die "Couldn't run remote command: ". $ssh->error;
 
#close the ssh session
undef $ssh;

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Error

# open_ex: ['ssh','-O','check','-T','-S','/root/.libnet-openssh-perl/u
+ser-10.253.10.10-25248-962213','-l','user','10.253.10.10','--']
# _waitpid(25251) => pid: 25251, rc: 0, err:
# open_ex: ['ssh','-S','/root/.libnet-openssh-perl/user-10.253.10.10-2
+5248-962213','-l','user','10.253.10.10','--']
Pseudo-terminal will not be allocated because stdin is not a terminal.
# _waitpid(25252) => pid: 25252, rc: 65280, err:
Couldn't run remote command: child exited with code 255 at script.pl l
+ine 42.
# open_ex: ['ssh','-O','exit','-T','-S','/root/.libnet-openssh-perl/us
+er-10.253.10.10-25248-962213','-l','user','10.253.10.10','--']
# _waitpid(25253) => pid: 25253, rc: 0, err:

[download]

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Re: How to solve Pseudo terminal issue OpenSSH
by salva (Canon) on May 12, 2015 at 07:43 UTC
    Pseudo-terminal will not be allocated because

    That is not an error but a (harmless) warning. The error is somewhere else.

    In any case, your code is not requesting a tty but ssh is trying to allocate it. May you have some entry on your ssh configuration file (usually at ~/.ssh/config) requesting it?

    In order to discover the real error, enable debugging for ssh and post the output: 

    $ssh = Net::OpenSSH->new(..., master_opts => '-vvvv');

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      Salva,

      Adding verbose to script. To my knowledge of understanding, i can see start in command execution, but closing the channel 0 abruptly. Please help

      [root@-01 wlgw]# perl wlgw4.pl
OpenSSH_5.3p1, OpenSSL 1.0.0-fips 29 Mar 2010
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Applying options for *
debug2: ssh_connect: needpriv 0
debug1: Connecting to 10.10.10.10 [10.10.10.10] port 22.
debug1: Connection established.
debug1: permanently_set_uid: 0/0
debug1: identity file /root/.ssh/id_rsa type -1
debug1: identity file /root/.ssh/id_dsa type -1
debug1: Remote protocol version 2.0, remote software version OpenSSH_5
+.1
debug1: match: OpenSSH_5.1 pat OpenSSH*
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_5.3
debug2: fd 3 setting O_NONBLOCK
debug1: SSH2_MSG_KEXINIT sent
debug3: Wrote 792 bytes for a total of 813
debug1: SSH2_MSG_KEXINIT received
debug2: kex_parse_kexinit: diffie-hellman-group-exchange-sha256,diffie
+-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellm
+an-group1-sha1
debug2: kex_parse_kexinit: ssh-rsa,ssh-dss
debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256
+,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,a
+es256-cbc,arcfour,rijndael-cbc@lysator.liu.se
debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256
+,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,a
+es256-cbc,arcfour,rijndael-cbc@lysator.liu.se
debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,umac-64@openssh.com,hmac
+-ripemd160,hmac-ripemd160@openssh.com,hmac-sha1-96,hmac-md5-96
debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,umac-64@openssh.com,hmac
+-ripemd160,hmac-ripemd160@openssh.com,hmac-sha1-96,hmac-md5-96
debug2: kex_parse_kexinit: none,zlib@openssh.com,zlib
debug2: kex_parse_kexinit: none,zlib@openssh.com,zlib
debug2: kex_parse_kexinit: 
debug2: kex_parse_kexinit: 
debug2: kex_parse_kexinit: first_kex_follows 0 
debug2: kex_parse_kexinit: reserved 0 
debug2: kex_parse_kexinit: diffie-hellman-group-exchange-sha256,diffie
+-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellm
+an-group1-sha1
debug2: kex_parse_kexinit: ssh-rsa
debug2: kex_parse_kexinit: aes128-cbc,3des-cbc,blowfish-cbc,cast128-cb
+c,arcfour128,arcfour256,arcfour,aes192-cbc,aes256-cbc,rijndael-cbc@ly
+sator.liu.se,aes128-ctr,aes192-ctr,aes256-ctr
debug2: kex_parse_kexinit: aes128-cbc,3des-cbc,blowfish-cbc,cast128-cb
+c,arcfour128,arcfour256,arcfour,aes192-cbc,aes256-cbc,rijndael-cbc@ly
+sator.liu.se,aes128-ctr,aes192-ctr,aes256-ctr
debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,umac-64@openssh.com,hmac
+-ripemd160,hmac-ripemd160@openssh.com,hmac-sha1-96,hmac-md5-96
debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,umac-64@openssh.com,hmac
+-ripemd160,hmac-ripemd160@openssh.com,hmac-sha1-96,hmac-md5-96
debug2: kex_parse_kexinit: none,zlib@openssh.com
debug2: kex_parse_kexinit: none,zlib@openssh.com
debug2: kex_parse_kexinit: 
debug2: kex_parse_kexinit: 
debug2: kex_parse_kexinit: first_kex_follows 0 
debug2: kex_parse_kexinit: reserved 0 
debug2: mac_setup: found hmac-md5
debug1: kex: server->client aes128-ctr hmac-md5 none
debug2: mac_setup: found hmac-md5
debug1: kex: client->server aes128-ctr hmac-md5 none
debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<1024<8192) sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP
debug3: Wrote 24 bytes for a total of 837
debug2: dh_gen_key: priv key bits set: 139/256
debug2: bits set: 1045/2048
debug1: SSH2_MSG_KEX_DH_GEX_INIT sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY
debug3: Wrote 272 bytes for a total of 1109
debug3: check_host_in_hostfile: filename /root/.ssh/known_hosts2
debug3: check_host_in_hostfile: match line 1
debug1: Host '10.10.10.10' is known and matches the RSA host key.
debug1: Found key in /root/.ssh/known_hosts2:1
debug2: bits set: 1013/2048
debug1: ssh_rsa_verify: signature correct
debug2: kex_derive_keys
debug2: set_newkeys: mode 1
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug3: Wrote 16 bytes for a total of 1125
debug2: set_newkeys: mode 0
debug1: SSH2_MSG_NEWKEYS received
debug1: SSH2_MSG_SERVICE_REQUEST sent
debug3: Wrote 48 bytes for a total of 1173
debug2: service_accept: ssh-userauth
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug2: key: /root/.ssh/id_rsa ((nil))
debug2: key: /root/.ssh/id_dsa ((nil))
debug3: Wrote 64 bytes for a total of 1237
debug3: input_userauth_banner

                        +=============================================
+==+
                        |                          |
                        +=============================================
+==+


debug1: Authentications that can continue: publickey,password,keyboard
+-interactive
debug3: start over, passed a different list publickey,password,keyboar
+d-interactive
debug3: preferred keyboard-interactive,password
debug3: authmethod_lookup keyboard-interactive
debug3: remaining preferred: password
debug3: authmethod_is_enabled keyboard-interactive
debug1: Next authentication method: keyboard-interactive
debug2: userauth_kbdint
debug2: we sent a keyboard-interactive packet, wait for reply
debug3: Wrote 96 bytes for a total of 1333
debug1: Authentications that can continue: publickey,password,keyboard
+-interactive
debug2: we did not send a packet, disable method
debug3: authmethod_lookup password
debug3: remaining preferred: 
debug3: authmethod_is_enabled password
debug1: Next authentication method: password
debug3: packet_send2: adding 64 (len 56 padlen 8 extra_pad 64)
debug2: we sent a password packet, wait for reply
debug3: Wrote 144 bytes for a total of 1477
debug1: Authentication succeeded (password).
debug1: setting up multiplex master socket
debug2: fd 4 setting O_NONBLOCK
debug1: Entering interactive session.
debug3: fd 5 is not O_NONBLOCK
debug3: ssh_msg_recv entering
debug3: ssh_msg_send: type 2
debug3: fd 5 is not O_NONBLOCK
debug3: ssh_msg_recv entering
debug3: ssh_msg_send: type 2
debug3: ssh_msg_recv entering
debug3: muxserver_accept_control: receiving 1 env vars
debug2: muxserver_accept_control: accepted tty 0, subsys 0, cmd show w
+ag sub
debug2: muxserver_accept_control: got fds stdin 6, stdout 7, stderr 8
debug3: ssh_msg_send: type 2
debug2: fd 5 setting O_NONBLOCK
debug1: channel 0: new [client-session]
debug3: muxserver_accept_control: channel_new: 0
debug2: channel 0: send open
debug3: Wrote 64 bytes for a total of 1541
debug2: callback start
debug2: client_session2_setup: id 0
debug1: Sending environment.
debug1: Sending env LANG = en_US.UTF-8
debug2: channel 0: request env confirm 0
debug1: Sending command: show wag sub
debug2: channel 0: request exec confirm 1
debug2: callback done
debug2: channel 0: open confirm rwindow 0 rmax 32768
debug3: Wrote 128 bytes for a total of 1669
debug2: channel 0: rcvd adjust 2097152
debug2: channel_input_status_confirm: type 99 id 0
debug2: exec request accepted on channel 0
debug1: client_input_channel_req: channel 0 rtype exit-status reply 0
debug1: client_input_channel_req: channel 0 rtype eow@openssh.com repl
+y 0
debug2: channel 0: rcvd eow
debug2: channel 0: close_read
debug2: channel 0: input open -> closed
debug2: channel 0: rcvd eof
debug2: channel 0: output open -> drain
debug2: channel 0: obuf empty
debug2: channel 0: close_write
debug2: channel 0: output drain -> closed
debug2: channel 0: rcvd close
debug3: channel 0: will not send data after close
debug2: channel 0: send close
debug2: channel 0: is dead
debug2: channel 0: garbage collecting
debug1: channel 0: free: client-session, nchannels 1
debug3: channel 0: status: The following connections are open:
  #0 client-session (t4 r0 i3/0 o3/0 fd -1/-1 cfd 5)

debug3: channel 0: close_fds r -1 w -1 e 8 c 5
debug3: Wrote 32 bytes for a total of 1701
debug3: fd 5 is not O_NONBLOCK
debug3: ssh_msg_recv entering
debug3: ssh_msg_send: type 2
debug3: Wrote 64 bytes for a total of 1765
Transferred: sent 1600, received 3072 bytes, in 0.2 seconds
Bytes per second: sent 7345.1, received 14102.7
debug1: Exit status -1
[root@-01 wlgw]#

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        What do you get when you pass the command as stdin_data?

        BTW, enable debugging for both Net::OpenSSH and the underlaying ssh.

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Re: How to solve Pseudo terminal issue OpenSSH
by Anonymous Monk on May 11, 2015 at 22:18 UTC

    Are you just trying to execute the command "show" with the argument "clock"? If so, why are you using stdin_data at all? Shouldn't my @output = $ssh->capture(@cmd); be enough?

    a remote ox

    Not sure what OS oxen run... j/k ;-)

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      Still same issue with my @output = $ssh->capture(@cmd); 

      # open_ex: ['ssh','-O','check','-T','-S','/root/.libnet-openssh-perl/u
+ser-10.253.10.10-25316-608967','-l','user','10.253.10.10','--']
# _waitpid(25319) => pid: 25319, rc: 0, err:
# open_ex: ['ssh','-S','/root/.libnet-openssh-perl/user-10.253.10.10-2
+5316-608967','-l','user','10.253.10.10','--','show clock']
# _waitpid(25320) => pid: 25320, rc: 0, err:
# open_ex: ['ssh','-O','exit','-T','-S','/root/.libnet-openssh-perl/us
+er-10.253.10.10-25316-608967','-l','user','10.253.10.10','--']
# _waitpid(25321) => pid: 25321, rc: 0, err:

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Re: How to solve Pseudo terminal issue OpenSSH
by pme (Monsignor) on May 12, 2015 at 11:52 UTC
    Hi waytoperl,

    What does 'show clock' command do? If it is screen-based command then you have to force the pseudo-terminal creation like this (not tested, Net::OpenSSH is not installed on my box): 

    my $ssh = Net::OpenSSH->new("$host", user => "$user", passwd => "$pass
+wd", timeout => 90, tty => 1 );

    [download]
    You can read ssh for the details: 
       -t         Force pseudo-tty allocation.  This    can be used to exe
+cute arbi-
         trary screen-based    programs on a remote machine, which can
+    be
         very useful, e.g. when implementing menu services.     Multip
+le -t
         options force tty allocation, even    if ssh has no local tty
+.

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      What does 'show clock' command do?

      Will display remote machine clock

      Force creation of Pseudo-terminal failed with an error

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