wolfssh

wolfSSL's Embeddable SSH Server

dependencies

wolfSSH is dependent on wolfCrypt. The simplest configuration of wolfSSL required for wolfSSH is the default build.

$ cd wolfssl
$ ./configure [OPTIONS] --enable-ssh
$ make check
$ sudo make install

To use the key generation function in wolfSSH, wolfSSL will need to be configured with keygen: --enable-keygen.

If the bulk of wolfSSL code isn't desired, wolfSSL can be configured with the crypto only option: --enable-cryptonly.

building

From the source directory run:

$ ./autogen.sh
$ ./configure
$ make
$ make check

The autogen.sh script only has to be run the first time after cloning the repository. If you have already run it or are using code from a source archive, you should skip it.

For building under Windows with Visual Studio, see the file "ide/winvs/README.md".

NOTE: On resource constrained devices the DEFAULT_WINDOW_SZ may need to be set to a lower size. By default channels are set to handle 1 Mb of data being sent and received. An example of setting a lower window size for new channels would be as follows "./configure C_EXTRA_FLAGS=-DDEFAULT_WINDOW_SZ=16384"

examples

The directory examples contains an echoserver that any client should be able to connect to. From the terminal run:

$ ./examples/echoserver/echoserver

From another terminal run:

$ ssh_client localhost -p 22222

The server will send a canned banner to the client:

wolfSSH Example Echo Server

Characters typed into the client will be echoed to the screen by the server. If the characters are echoed twice, the client has local echo enabled. The echo server isn't being a proper terminal so the CR/LF translation will not work as expected.

testing notes

After cloning the repository, be sure to make the testing private keys read- only for the user, otherwise ssh_client will tell you to do it.

$ chmod 0600 ./keys/gretel-key-rsa.pem ./keys/hansel-key-rsa.pem \
             ./keys/gretel-key-ecc.pem ./keys/hansel-key-ecc.pem

Authentication against the example echoserver can be done with a password or public key. To use a password the command line:

$ ssh_client -p 22222 USER@localhost

Where the USER and password pairs are:

jill:upthehill
jack:fetchapail

To use public key authentication use the command line:

$ ssh_client -i ./keys/key-USER.pem -p 22222 USER@localhost

Where the user can be gretel or hansel.

scp support

wolfSSH includes server-side support for scp, which includes support for both copying files 'to' the server, and copying files 'from' the server. Both single file and recursive directory copy are supported with the default send and receive callbacks.

To compile wolfSSH with scp support, use the --enable-scp build option or define WOLFSSL_SCP:

$ ./configure --enable-scp
$ make

For full API usage and implementation details, please see the wolfSSH User Manual.

The wolfSSL example server has been set up to accept a single scp request, and is compiled by default when compiling the wolfSSH library. To start the example server, run:

$ ./examples/server/server

Standard scp commands can be used on the client side. The following are a few examples, where scp represents the ssh client you are using.

To copy a single file TO the server, using the default example user "jill":

$ scp -P 22222 <local_file> jill@127.0.0.1:<remote_path>

To copy the same single file TO the server, but with timestamp and in verbose mode:

$ scp -v -p -P 22222 <local_file> jill@127.0.0.1:<remote_path>

To recursively copy a directory TO the server:

$ scp -P 22222 -r <local_dir> jill@127.0.0.1:<remote_dir>

To copy a single file FROM the server to the local client:

$ scp -P 22222 jill@127.0.0.1:<remote_file> <local_path>

To recursively copy a directory FROM the server to the local client:

$ scp -P 22222 -r jill@127.0.0.1:<remote_dir> <local_path>

release notes

wolfSSH v1.2.0 (09/26/2017)

• Added ECDH Group Exchange with SHA2 hashing and curves nistp256, nistp384, and nistp521.
• Added ECDSA with SHA2 hashing and curves nistp256, nistp384, and nistp521.
• Added client support.
• Added an example client that talks to the echoserver.
• Changed the echoserver to allow only one connection, but multiple connections are allowed with a command line option.
• Added option to echoserver to offer an ECC public key.
• Added a Visual Studio solution to build the library, examples, and tests.
• Other bug fixes and enhancements.

wolfSSH v1.1.0 (06/16/2017)

• Added DH Group Exchange with SHA-256 hashing to the key exchange.
• Removed the canned banner and provided a function to set a banner string. If no sting is provided, no banner is sent.
• Expanded the make checking to include an API test.
• Added a function that returns session statistics.
• When connecting to the echoserver, hitting Ctrl-E will give you some session statistics.
• Parse and reply to the Global Request message.
• Fixed a bug with client initiated rekeying.
• Fixed a bug with the GetString function.
• Other small bug fixes and enhancements.

wolfSSH v1.0.0 (10/24/2016)

Initial release.