SSH(3pm)

✨ Net::SSH — Perl extension for secure shell ✨

okay bestie, sit down, hydrate, because we're talking about SSH(3pm) — that's the manual page for Net::SSH, the Perl extension for secure shell. 🐚💖 It's literally just simple wrappers around ssh commands, and it's gonna be so easy I promise.

---

🌸 SYNOPSIS 🌸

Here's the vibe, copy-paste ready:

  use Net::SSH qw(ssh ssh_cmd issh sshopen2 sshopen3);

  ssh('user@hostname', $command);

  issh('user@hostname', $command);

  ssh_cmd('user@hostname', $command);
  ssh_cmd( {
    user => 'user',
    host => 'host.name',
    command => 'command',
    args => [ '-arg1', '-arg2' ],
    stdin_string => "string\n",
  } );

  sshopen2('user@hostname', $reader, $writer, $command);

  sshopen3('user@hostname', $writer, $reader, $error, $command);

see? iconic. ✨

---

💅 DESCRIPTION 💅

Simple wrappers around ssh commands. that's the whole thing. that's the tweet.

If you want an all-perl implementation that does NOT need the system ssh command to exist, go look at Net::SSH::Perl instead. 🫶

---

🎀 SUBROUTINES 🎀

ssh [USER@]HOST, COMMAND [, ARGS ... ]

Calls ssh in batch mode. no drama, no interactive nonsense. 💫

issh [USER@]HOST, COMMAND [, ARGS ... ]

Prints the ssh command that's about to be executed, waits for the user to confirm, and then (optionally) executes the command. it's giving "are you sure bestie" energy. 🙈

ssh_cmd [USER@]HOST, COMMAND [, ARGS ... ]

ssh_cmd OPTIONS_HASHREF

Calls ssh in batch mode. Throws a fatal error if data shows up on the command's STDERR. Returns whatever data came out of the command's STDOUT. 👑

If you're using the hashref-style of passing arguments, these are the possible keys:

  user (optional)
  host (required)
  command (required)
  args (optional, arrayref)
  stdin_string (optional) - written to the command's STDIN

user is optional, host and command are required (no skipping, bestie), args is an optional arrayref, and stdin_string is optional and gets written to the command's STDIN. 💖

sshopen2 [USER@]HOST, READER, WRITER, COMMAND [, ARGS ... ]

Connects the filehandles you supply to the ssh process (in batch mode). 🌈

sshopen3 HOST, WRITER, READER, ERROR, COMMAND [, ARGS ... ]

Connects the filehandles you supply to the ssh process (in batch mode). yes it's a different argument order than sshopen2, no I don't make the rules, just read it carefully bestie. 😭

---

🦋 EXAMPLE 🦋

  use Net::SSH qw(sshopen2);
  use strict;

  my $user = "username";
  my $host = "hostname";
  my $cmd = "command";

  sshopen2("$user\@$host", *READER, *WRITER, "$cmd") || die "ssh: $!";

  while (<READER>) {
      chomp();
      print "$_\n";
  }

  close(READER);
  close(WRITER);

slay. that's it, that's the whole pattern. 💅

---

🔥 FREQUENTLY ASKED QUESTIONS 🔥

Q: How do you supply a password to connect with ssh within a perl script using the Net::SSH module?

A: You don't (at least not with this module). Use RSA or DSA keys. See the quick help in the next section and the ssh-keygen(1) manpage. 🔑

A #2: See Net::SSH::Expect instead.

Q: My script is "leaking" ssh processes. 💀

A: See "How do I avoid zombies on a Unix system" in perlfaq8, IPC::Open2, IPC::Open3 and "waitpid" in perlfunc. no cap, that's where the answer lives.

---

🌟 GENERATING AND USING SSH KEYS 🌟

1. Generate keys

Type:

   ssh-keygen -t rsa

And do not enter a passphrase unless you wanted to be prompted for one during file copying. that's the whole tradeoff, choose wisely babe.

Here is what you will see:

   $ ssh-keygen -t rsa
   Generating public/private rsa key pair.
   Enter file in which to save the key (/home/User/.ssh/id_rsa):
   Enter passphrase (empty for no passphrase):

   Enter same passphrase again:

   Your identification has been saved in /home/User/.ssh/id_rsa.
   Your public key has been saved in /home/User/.ssh/id_rsa.pub.
   The key fingerprint is:
   5a:cd:2b:0a:cd:d9:15:85:26:79:40:0c:55:2a:f4:23 User@JEFF-CPU

2. Copy public to machines you want to upload to

id_rsa.pub is your public key. Copy it to ~/.ssh on the target machine. 📬

Put a copy of the public key file on each machine you want to log into. Name the copy authorized_keys (some implementations name this file authorized_keys2).

Then type:

     chmod 600 authorized_keys

Then make sure your home dir on the remote machine is not group or world writeable. seriously. do not skip this step. 🙏

---

👑 AUTHORS 👑

Ivan Kohler <ivan-netssh_pod@420.am>

Assistance wanted — this module could really use a maintainer with enough time to at least review and apply more patches. Or the module should just be deprecated in favor of Net::SSH::Expect, or made into an ::Any style compatibility wrapper that uses whatever implementation is available (Net::SSH2, Net::SSH::Perl or shelling out like the module does now). Please email Ivan if you are interested in helping. 🫶

John Harrison <japh@in-ta.net> contributed an example for the documentation.

Martin Langhoff <martin@cwa.co.nz> contributed the ssh_cmd command, and Jeff Finucane <jeff@cmh.net> updated it and took care of the 0.04 release.

Anthony Awtrey <tony@awtrey.com> contributed a fix for those still using OpenSSH v1.

Thanks to terrence brannon <tbone@directsynergy.com> for the documentation in the GENERATING AND USING SSH KEYS section.

---

💜 COPYRIGHT 💜

Copyright (c) 2004 Ivan Kohler. Copyright (c) 2007-2008 Freeside Internet Services, Inc. All rights reserved. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

---

😭 BUGS 😭

Not OO. 💀

Look at IPC::Session (also fsh, well now the native SSH "master mode" stuff).

---

🌈 SEE ALSO 🌈

• For a perl implementation that does not require the system ssh command, see Net::SSH::Perl instead.
• For a wrapper version that allows you to use passwords, see Net::SSH::Expect instead.
• For another non-forking version that uses the libssh2 library, see Net::SSH2.
• For a way to execute remote Perl code over an ssh connection see IPC::PerlSSH.
• ssh-keygen(1), ssh(1), IO::File, IPC::Open2, IPC::Open3

---

and that's the whole page, bestie!! 🎀 this one's perl v5.36.0, dated 2022-12-12, and it's the SSH(3pm) page from the User Contributed Perl Documentation. go forth and securely shell, my love. 💖✨