SSF provides a simple way to route an SSF connection between a client and a server through a list of SSF relay servers without protocol or cryptographic overhead. At this point, the traffic is decrypted as it is received by a relay and re-encrypted to be sent to the next relay or final destination. This means that the data will be encrypted between each relay but will transit unencrypted on the relay itself. It is therefore essential that the relay servers be secure and controlled by the owner of the data.

If users were to express the need, future versions could add a second cryptographic layer between the client and the destination server so that the data remained encrypted by this layer on every relay.

Required files

With default options, the following files and folders should be in the directory of execution of a client or a server (see the Security features section if you do not know how to generate them): ./certs/dh4096.pem

./certs/certificate.crt

./certs/private.key

./certs/trusted/ca.crt Where : dh4096.pem contains the Diffie-Hellman parameters needed for the establishment of session keys

certificate.crt and private.key are the certificate and the private key of the SSF server or client

ca.crt is the concatenated list of root certificates trusted by the SSF server or client The certificate and the private key should be unique to each SSF client or server. Moreover, a client will be able to connect to a server if two conditions are fulfilled: One of the certification authority which signed the server certificate is present in the trusted list of the client

One of the certification authority which signed the client certificate is present in the trusted list of the server In order to customize the paths and file names, the command line accepts a configuration file option -c.

An example is given below.

Configuration file

The configuration file is JSON format file in which several options can be specified. At this point, only security options relative to TLS use can be customized. See below an example of configuration file. For more information about TLS and SSF security see the Security features section. { "ssf": { "arguments": "", "circuit": [], "tls" : { "ca_cert_path": "./certs/trusted/ca.crt", "cert_path": "./certs/certificate.crt", "key_path": "./certs/private.key", "key_password": "", "dh_path": "./certs/dh4096.pem", "cipher_alg": "DHE-RSA-AES256-GCM-SHA384" }, "http_proxy" : { "host": "", "port": "", "user_agent": "", "credentials": { "username": "", "password": "", "domain": "", "reuse_ntlm": "true", "reuse_nego": "true" } }, "services": { "datagram_forwarder": { "enable": true }, "datagram_listener": { "enable": true, "gateway_ports": false }, "stream_forwarder": { "enable": true }, "stream_listener": { "enable": true, "gateway_ports": false }, "copy": { "enable": false }, "shell": { "enable": false, "path": "/bin/bash|C:\\windows\\system32\\cmd.exe", "args": "" }, "socks": { "enable": true } } } } arguments use configuration arguments instead of given CLI arguments circuit relay chain servers used to establish the connection to the remote server tls.ca_cert_path relative or absolute path to the CA certificate file tls.cert_path relative or absolute path to the instance certificate file tls.key_path relative or absolute path to the private key file tls.key_password the password protecting the private key (if any) tls.dh_path relative or absolute path to the Diffie-Hellman file tls.cipher_alg List of allowed SSL cipher suite (see OpenSSL documentation for more information) http_proxy.host HTTP proxy host http_proxy.port HTTP proxy port http_proxy.user_agent User agent in CONNECT request http_proxy.credentials.username proxy username credentials http_proxy.credentials.password proxy password credentials http_proxy.credentials.domain user domain (NTLM and Negotiate auth on Windows only) http_proxy.credentials.reuse_ntlm reuse current computer user credentials to authenticate with proxy NTLM auth (SSO) http_proxy.credentials.reuse_kerb reuse current computer user credentials (Kerberos ticket) to authenticate with proxy Negotiate auth (SSO) services.*.enable enable/disable local microservice services.*.gateway_ports enable/disable gateway ports services.shell.path binary path used for process creation services.shell.args binary arguments used for process creation For an SSF server, if the private key is encrypted but no password was provided with the configuration file, all connections will fail.

However, for an SSF client, a password prompt will be presented to the user. It will give him the opportunity to enter the password, if needed.

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