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As mentioned earlier, OpenSSH is also capable of replicating the functionality of rcp and ftp. The rcp command allows you to copy a file to a remote system from the command line. The OpenSSH equivalent of rcp is called scp, and Listing 3-34 shows scp working. Listing 3-34. Using scp for Remote Copy puppy$ scp /root/example.txt bob@kitten:/root root@kitten's password: example.txt 100% |*****************************|

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Listing 3-34 shows sending via scp the file example.txt from the directory /root on the local host to the /root directory on the remote system kitten. To do this, I signed on as the user bob at kitten. You can send one file to multiple hosts as well by adding additional user@remote.host:/path/to/destination statements to the scp command. You can use a few additional options with the scp command (see Table 3-11). Table 3-11. scp Command-Line Options

Preserves modification times, access times, and modes from the original file Recursively copies entire directories Enables verbose mode Enables batch mod Specifies a particular private key Disables the progress meter Enables ssh compression

The first option, -p, tells scp to preserve the details including the modification time and permissions of the original file and give those details to the copied file. If you specify the -r option with a directory when using the scp command, then scp will recursively copy the entire directory. The -v option enables verbose logging. The -B option allows you to send files in batch mode, which is designed to allow you send files without scp needing to prompt for passwords. You achieve this by using public-key encryption with public keys that do not have a passphrase, as discussed in the ssh-agent and Agent Forwarding section. So you need to ensure the public key of the sending system is added to the authorized_keys file on the target system. Then when you use scp in batch mode (for example, in a cron job), you are not prompted for a password and the cron job requires no interactive input. Listing 3-35 shows this at work in a cron entry. Listing 3-35. Using scp in Batch Mode in a crontab Entry 15 * * * * /usr/bin/scp -q -i /root/.ssh/nopasskitten_id -B /home/bob/example.txt bob@kitten:/home/bob/recvfile.txt Listing 3-35 shows a crontab entry sending a file every hour to a remote server in batch mode. I have also used the -i option to specify a particular private key to use. This allows you to have a separate set of keys for your batch transactions without a passphrase and another key for purposes such as shell access. Of the last two options, -q disables the progress meter that you can see in Listing 3-34, and -C enables ssh compression. The sftp command provides a secure version of the ftp command. It works in nearly identical format to a standard FTP session. You enable the sftp server in the sshd_config file, and it is started as a subsystem of the sshd daemon. You will see the configuration for this in the Configuring ssh and sshd section a little later. Listing 3-36 shows starting an sftp connection to a remote system. Listing 3-36. Initiating an sftp Connection and an sftp Session puppy$ sftp -C bob@kitten Connecting to kitten... bob@kitten's password: sftp> cd /root sftp> put example.txt Uploading example.txt to /root/example.txt sftp> exit As you can see from Listing 3-36 you can also use the -C option to enable ssh compression. You can also see that you can use the standard FTP commands to perform functions within the sftp connection. Additionally, you can use the -b option to specify a file containing a series of commands that you can input in batch mode and the -v option to increase the logging level.