sftp - secure file transfer protocol
sftp is a program that allows the transfer of files
between two unix hosts. It is generally used interactively,
although its functions may be scripted with a shell script. All data transfer through sftp is secure; this includes the login information, so that data compromis is more difficult that without the secure functionality.
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[loriotg@gollum ~] sftp apollo
Connecting to apollo...
sftp> quit
[loriotg@gollum ~]
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sftp apollo
command. The one argument (apollo) is the hostname of the computer to which you want to attach and transfer data to/from. In the example above, user loriotg on host gollum attached securely to host apollo. If the remote host does not recognize the user loriotg the host will request a password. In the case of LSC ATM students, all remote Linux machines will recognize the user. The user is then left with the sftp command prompt where subsequent actions such as retrieving files may be done. sftp may be terminated by entering the command
"quit".
interactive commands:
- navigating the local and remote filesystems within sftp
Once connected to a remote host you will be able to navigate its file system with thecdcommand. Unless the sftp host is configured differently, you will start in the home directory of the user that you authenticated your ftp connection with. Allcdcommands will be performed on the remote host's file system, not the local file system. By default, sftp will download any requested files to the current directory that the user's shell was in when the sftp program was started. If you wish to change the current working directory on the local machine you may use thelcdcommand ("local cd"). You may use the commandlsto show a listing of the files in the current directory on the remote host and the commandllsto show a listing of the files in the current directory of the local computer. Example sftp session below:
In the above example, user loriotg on host gollum connects to remote host apollo vis sftp, changes to the
[loriotg@gollum ~] pwd /mnt/homes/loriotg [loriotg@gollum ~] sftp apollo Connecting to apollo... sftp> pwd Remote working directory: /mnt/homes/loriotg sftp> lpwd Local working directory: /mnt/homes/loriotg sftp> cd test sftp> lcd test_fortran sftp> ls Halo alex brookd cart examples fkink fortran ftkink hello hello2 hosts macielj md md-ew md012 mdbnch occomm parcfd pibal.f pingpong ring srtest stream test testmpi sftp> lls dotprod dotprod_serial hello.f hello_serial.f output1 tint.f dotprod.f dotprod_serial.f hello_mpi.f kangaroo.hosts pibal.f tint.f~ dotprod.o file hello_serial output testdp.f sftp> help Available commands: bye Quit sftp cd path Change remote directory to 'path' chgrp grp path Change group of file 'path' to 'grp' chmod mode path Change permissions of file 'path' to 'mode' chown own path Change owner of file 'path' to 'own' df [-hi] [path] Display statistics for current directory or filesystem containing 'path' exit Quit sftp get [-P] remote-path [local-path] Download file help Display this help text lcd path Change local directory to 'path' lls [ls-options [path]] Display local directory listing lmkdir path Create local directory ln oldpath newpath Symlink remote file lpwd Print local working directory ls [-1aflnrSt] [path] Display remote directory listing lumask umask Set local umask to 'umask' mkdir path Create remote directory progress Toggle display of progress meter put [-P] local-path [remote-path] Upload file pwd Display remote working directory quit Quit sftp rename oldpath newpath Rename remote file rm path Delete remote file rmdir path Remove remote directory symlink oldpath newpath Symlink remote file version Show SFTP version !command Execute 'command' in local shell ! Escape to local shell ? Synonym for help sftp> quit [loriotg@gollum ~]testremote directory (on apollo) and to thetest_fortranlocal directory (on gollum) and lists files in each directory. User then issues the help command to list all sftp commands and quits the session. - sftp get command
Once connected to a remote host, thegetcommand will copy (get)a file from the remote host to the local host, as in the session below. Note which directory is local and which is remote.
sftp> pwd Remote working directory: /mnt/homes/loriotg sftp> cd hello sftp> pwd Remote working directory: /mnt/homes/loriotg/hello sftp> lcd test sftp> lls alex examples ftkink hello2 md md-ew pibal.f srtest testmpi brookd fkink Halo hosts md012 occomm pingpong stream cart fortran hello macielj mdbnch parcfd ring test sftp> ls hello hello.f hello.o hello_serial.f metlabhosts sftp> get hello.f Fetching /mnt/homes/loriotg/hello/hello.f to hello.f /mnt/homes/loriotg/hello/hello.f 100% 1944 1.9KB/s 00:00 sftp> lls alex examples ftkink hello2 macielj mdbnch parcfd ring test brookd fkink Halo hello.f md md-ew pibal.f srtest testmpi cart fortran hello hosts md012 occomm pingpong stream sftp> - sftp put command
The inverse of the get command is theputcommand. This will upload a file from the current local directory to the current remote directory.
sftp> pwd Remote working directory: /mnt/homes/loriotg sftp> lpwd Local working directory: /mnt/homes/loriotg/lab10 sftp> cd test sftp> lls met_em.d01.2000-01-24_12:00:00.nc met_em.d01.2000-01-25_00:00:00.nc met_em.d01.2000-01-24_18:00:00.nc met_em.d01.2000-01-25_06:00:00.nc sftp> put met_em.d01.2000-01-24_12:00:00.nc Uploading met_em.d01.2000-01-24_12:00:00.nc to /mnt/homes/loriotg/test/met_em.d01.2000-01-24_12:00:00.nc met_em.d01.2000-01-24_12:00:00.nc 100% 5340KB 5.2MB/s 00:00 sftp> - mget,mput commands
mgetandmputallow you to download or upload files (respectively) using common unix wildcard characters to specify what files to transfer.
>> [loriotg@gollum ~] sftp apollo Connecting to apollo... sftp> pwd Remote working directory: /mnt/homes/loriotg sftp> lcd lab10 sftp> lpwd Local working directory: /mnt/homes/loriotg/lab10 sftp> mget met_em* Fetching /mnt/homes/loriotg/met_em.d01.2000-01-24_12:00:00.nc to met_em.d01.2000-01-24_12:00:00.nc /mnt/homes/loriotg/met_em.d01.2000-01-24_12:0 100% 5340KB 5.2MB/s 00:00 Fetching /mnt/homes/loriotg/met_em.d01.2000-01-24_18:00:00.nc to met_em.d01.2000-01-24_18:00:00.nc /mnt/homes/loriotg/met_em.d01.2000-01-24_18:0 100% 5322KB 5.2MB/s 00:00 Fetching /mnt/homes/loriotg/met_em.d01.2000-01-25_00:00:00.nc to met_em.d01.2000-01-25_00:00:00.nc /mnt/homes/loriotg/met_em.d01.2000-01-25_00:0 100% 5340KB 5.2MB/s 00:01 Fetching /mnt/homes/loriotg/met_em.d01.2000-01-25_06:00:00.nc to met_em.d01.2000-01-25_06:00:00.nc /mnt/homes/loriotg/met_em.d01.2000-01-25_06:0 100% 5322KB 5.2MB/s 00:00 sftp> lls met_em.d01.2000-01-24_12:00:00.nc met_em.d01.2000-01-25_00:00:00.nc met_em.d01.2000-01-24_18:00:00.nc met_em.d01.2000-01-25_06:00:00.nc sftp>
- anonymous ftp
sftpcan be setup on the remote host to allow any user to login without a proper username or password. In this case, the username will be "anonymous" and the password may be anything. Typically, a connecting user would provide their email address as the password but it is usually not required. sftp servers do not support anonymous connections except in unusual circumstances. Downloads over web-based connections are the common methods of 'anonymous' file transfers. scp - secure copy
scpfunctions similar to the unixcpcommand with the difference being that you can specify remote files or directories as the source or destination of the copy function.scplikesftpuses the same encryption and authentication as thesshcommand.scpcan specify the remote host, username and path to the file in the following manner:username@host:/path/filename
"username" would be the name of the user account on the remote machine that will be used to log onto the remote host. "host" would be the hostname or network address of the remote host. "/path/filename" would be the absolute path to the file "filename" on the remote host. A few examples of file copies using
scpare below:- Copy file from remote host to local directory:
The first argument above, root@omega:/root/runme.sh specifies the source for the file copy.>> >> scp root@omega:/scripts/runme.sh /newscripts/ >>
scpwill log on to the host omega as the user named root. The host and username information is separated from the remote file and path by the colon ":" The file specified /scripts/runme.sh will be found on the remote host, omega, and copied from there to the directory /newscripts. - Copy file from remote host to current working directory:
The command above will connect to the host Omega, using the tuckerm account. The file on Omega, /path/to/some/file.txt, will be copied from its location on Omega to the current directory on the local machine.>> >> scp tuckerm@omega:/path/to/some/file.txt . >>
- Copy file from local host to directory on remote host:
In this example, the file localfile.txt will be copied from the current working directory on the local host to the host named kangaroo. On kangaroo, the file will be copied to the directory /path/to/place/file/ using the tuckerm account on kangaroo.>> >> scp localfile.txt tuckerm@kangaroo:/path/to/place/file/ >> - Copy file from local host to home directory on remote host:
This command will copy the file named file.dat located in the directory /absolulte/path/to/ on the local machine. It will be copied to tuckerm's home directory on kangaroo.>> >> scp /absolute/path/to/file.dat tuckerm@kangaroo: >>
- Copy file from remote host to local directory:
wget
wgetis a commandline file retrieval tool that can fetch files from ftp or web servers. It does not display the contents of the file, it only downloads a copy of the file to the current directory. There are many options that can modify the behavior of wget.
>> >> wget http://apollo.lsc.vsc.edu/index.html --18:33:19-- http://apollo.lsc.vsc.edu/index.html => `index.html' Resolving apollo.lsc.vsc.edu... done. Connecting to apollo.lsc.vsc.edu[155.42.21.5]:80... connected. HTTP request sent, awaiting response... 200 OK Length: unspecified [text/html] [ <=> ] 16,843 498.43K/s 18:33:19 (498.43 KB/s) - `index.html' saved [16843] >>wget fetching files via anonymous ftp. In the case of
wgetanonymous filetransfer is supported on common remote hosts. However this is not as secure as sftp:
>> >> wget ftp.us.debian.org:/debian/README --18:35:02-- ftp://ftp.us.debian.org//debian/README => `README' Resolving ftp.us.debian.org... done. Connecting to ftp.us.debian.org[204.152.189.120]:21... connected. Logging in as anonymous ... Logged in! ==> SYST ... done. ==> PWD ... done. ==> TYPE I ... done. ==> CWD /debian ... done. ==> PORT ... done. ==> RETR README ... done. Length: 943 (unauthoritative) 100%[==============================================================>] 943 3.18K/s ETA 00:00 18:35:14 (3.18 KB/s) - `README' saved [943] >>