.TH SSH-AUDIT 1 "March 2, 2021" .SH NAME \fBssh-audit\fP \- SSH server & client configuration auditor .SH SYNOPSIS .B ssh-audit .RI [ options ] " " .SH DESCRIPTION .PP \fBssh-audit\fP analyzes the configuration of SSH servers & clients, then warns the user of weak, obsolete, and/or un-tested cryptographic primitives. It is very useful for hardening SSH tunnels, which by default tend to be optimized for compatibility, not security. .PP See for official hardening guides for common platforms. .SH OPTIONS .TP .B -h, \-\-help .br Print short summary of options. .TP .B -1, \-\-ssh1 .br Only perform an audit using SSH protocol version 1. .TP .B -2, \-\-ssh2 .br Only perform an audit using SSH protocol version 2. .TP .B -4, \-\-ipv4 .br Prioritize the usage of IPv4. .TP .B -6, \-\-ipv6 .br Prioritize the usage of IPv6. .TP .B -b, \-\-batch .br Enables grepable output. .TP .B -c, \-\-client\-audit .br Starts a server on port 2222 to audit client software configuration. Use -p/--port= to change port and -t/--timeout= to change listen timeout. .TP .B -d, \-\-debug .br Enable debug output. .TP .B -j, \-\-json .br Output results in JSON format. Specify twice (-jj) to enable indent printing (useful for debugging). .TP .B -l, \-\-level= .br Specify the minimum output level. Default is info. .TP .B -L, \-\-list-policies .br List all official, built-in policies for common systems. Their full names can then be passed to -P/--policy. .TP .B \-\-lookup= .br Look up the security information of an algorithm(s) in the internal database. Does not connect to a server. .TP .B -m, \-\-manual .br Print the man page (Windows only). .TP .B -M, \-\-make-policy= .br Creates a policy based on the target server. Useful when other servers should be compared to the target server's custom configuration (i.e.: a cluster environment). Note that the resulting policy can be edited manually. .TP .B -n, \-\-no-colors .br Disable color output. .TP .B -p, \-\-port= .br The TCP port to connect to when auditing a server, or the port to listen on when auditing a client. .TP .B -P, \-\-policy=<"built-in policy name" | path/to/custom_policy.txt> .br Runs a policy audit against a target using the specified policy (see \fBPOLICY AUDIT\fP section for detailed description of this mode of operation). Combine with -c/--client-audit to audit a client configuration instead of a server. Use -L/--list-policies to list all official, built-in policies for common systems. .TP .B -t, \-\-timeout= .br The timeout, in seconds, for creating connections and reading data from the socket. Default is 5. .TP .B -T, \-\-targets= .br A file containing a list of target hosts. Each line must have one host, in the format of HOST[:PORT]. Use --threads to control concurrent scans. .TP .B \-\-threads= .br The number of threads to use when scanning multiple targets (with -T/--targets). Default is 32. .TP .B -v, \-\-verbose .br Enable verbose output. .SH STANDARD AUDIT .PP By default, \fBssh-audit\fP performs a standard audit. That is, it enumerates all host key types, key exchanges, ciphers, MACs, and other information, then color-codes them in output to the user. Cryptographic primitives with potential issues are displayed in yellow; primitives with serious flaws are displayed in red. .SH POLICY AUDIT .PP When the -P/--policy option is used, \fBssh-audit\fP performs a policy audit. The target's host key types, key exchanges, ciphers, MACs, and other information is compared to a set of expected values defined in the specified policy file. If everything matches, only a short message stating a passing result is reported. Otherwise, the field(s) that did not match are reported. .PP Policy auditing is helpful for ensuring a group of related servers are properly hardened to an exact specification. .PP The set of official built-in policies can be viewed with -L/--list-policies. Multiple servers can be audited with -T/--targets=. Custom policies can be made from an ideal target server with -M/--make-policy=. .SH EXAMPLES .LP Basic server auditing: .RS .nf ssh-audit localhost ssh-audit 127.0.0.1 ssh-audit 127.0.0.1:222 ssh-audit ::1 ssh-audit [::1]:222 .fi .RE .LP To run a standard audit against many servers (place targets into servers.txt, one on each line in the format of HOST[:PORT]): .RS .nf ssh-audit -T servers.txt .fi .RE .LP To audit a client configuration (listens on port 2222 by default; connect using "ssh -p 2222 anything@localhost"): .RS .nf ssh-audit -c .fi .RE .LP To audit a client configuration, with a listener on port 4567: .RS .nf ssh-audit -c -p 4567 .fi .RE .LP To list all official built-in policies (hint: use their full names with -P/--policy): .RS .nf ssh-audit -L .fi .RE .LP To run a built-in policy audit against a server (hint: use -L to see list of built-in policies): .RS .nf ssh-audit -P "Hardened Ubuntu Server 20.04 LTS (version 1)" targetserver .fi .RE .LP To run a custom policy audit against a server (hint: use -M/--make-policy to create a custom policy file): .RS .nf ssh-audit -P path/to/server_policy.txt targetserver .fi .RE .LP To run a policy audit against a client: .RS .nf ssh-audit -c -P ["policy name" | path/to/client_policy.txt] .fi .RE .LP To run a policy audit against many servers: .RS .nf ssh-audit -T servers.txt -P ["policy name" | path/to/server_policy.txt] .fi .RE .LP To create a policy based on a target server (which can be manually edited; see official built-in policies for syntax examples): .RS .nf ssh-audit -M new_policy.txt targetserver .fi .RE .SH RETURN VALUES When a successful connection is made and all algorithms are rated as "good", \fBssh-audit\fP returns 0. Other possible return values are: .RS .nf 1 = connection error 2 = at least one algorithm warning was found 3 = at least one algorithm failure was found = unknown error .fi .RE .SH SSH HARDENING GUIDES Hardening guides for common platforms can be found at: .SH BUG REPORTS Please file bug reports as a Github Issue at: .SH AUTHOR .LP \fBssh-audit\fP was originally written by Andris Raugulis , and maintained from 2015 to 2017. .br .LP Maintainership was assumed and development was resumed in 2017 by Joe Testa .