Ports and connections

smbclient

Also smb, cifs, file share, network drive

Talks to an SMB/CIFS file server: lists its shares and reads or writes files, like a mounted network drive.

SMB (Server Message Block, also CIFS) is how Windows file sharing and network drives work, on TCP port 445. A server offers named shares (folders); smbclient lists them and opens one as //server/share, then runs commands like ls, get and put inside it. Plain SMB is not encrypted, so a capture of a transfer shows the file's contents in the clear.

smbclient command usage

smbclient -L //SERVER -U USER%PASSWORD
smbclient //SERVER/SHARE -U USER%PASSWORD -c COMMAND

Options

-L //SERVER: list the shares the server offers
-U alice%s3cret: log in as this user with this password
-c "get file": run one command in the share and exit
-t 5: give up on an operation after 5 seconds

smbclient examples

smbclient -L //10.0.1.11 -U alice%s3cret: Lists the file server's shares, logged in as alice.
smbclient //10.0.1.11/finance -U alice%s3cret -c "ls": Opens the finance share and lists its files.
smbclient //10.0.1.11/finance -U alice%s3cret -c "get q3-report.txt q3-report.txt": Downloads one file from the finance share.

Reading the output

$ smbclient -L //10.0.1.11 -U alice%s3cret
	Sharename       Type      Comment
	---------       ----      -------
	finance         Disk
	dropbox         Disk
	IPC$            IPC       IPC Service (fileServer)
SMB1 disabled -- no workgroup available

Sharename: the folders the server offers; open one as //server/finance.
IPC$ is the control channel, not a file share.
SMB1 disabled means the server speaks only the safer SMB2/3.

Pitfalls

Plain SMB sends file contents unencrypted: anyone capturing on the LAN can read them.

Run it on real machines