Testing a Rejected cipher Simply use the '-cipher' argument to openssl to limit the cipher suite which your client will support to the one cipher you want to test. You would not be able to do this or see this if the cipher had been rejected, obviously; you can only talk to the HTTP server if the SSL connection was nailed up successfully. Caveats This is relatively easy in openssl command line. Improve this answer. Sign up or log in Sign up using Google. Sign up using Facebook.
Sign up using Email and Password. Post as a guest Name. Email Required, but never shown. The Overflow Blog. Podcast Explaining the semiconductor shortage, and how it might end. Does ES6 make JavaScript frameworks obsolete? Featured on Meta. In the following example, I use a HEAD request because it instructs the server not to send the response body:.
This switch ensures that the newlines you type are translated to a carriage return plus line feed combo to ensure string HTTP compliance. Now we know that the TLS communication layer is working: we got through to the HTTP server, submitted a request, and received a response back. The first couple of lines will show the information about the server certificate:.
The next section in the output lists all the certificates presented by the server in the order in which they were delivered:. For each certificate, the first line shows the subject and the second line shows the issuer information.
This part is very useful when you need to see exactly what certificates are sent; browser certificate viewers typically display reconstructed certificate chains that can be almost completely different from the presented ones. To determine if the chain is nominally correct, you might wish to verify that the subjects and issuers match. You start with the leaf web server certificate at the top, and then you go down the list, matching the issuer of the current certificate to the subject of the next.
The last issuer you see can point to some root certificate that is not in the chain, or—if the self-signed root is included—it can point to itself. If you wish to obtain the entire chain, use the -showcerts switch. The following is a lot of information about the TLS connection, most of which is self-explanatory:.
The most important information here is the protocol version TLS 1. Do note that protocol information appears in two locations, which is potentially confusing when different versions are shown.
The first location describes the minimum protocol requirement with the negotiated cipher suite, while the second location points to the actual protocol version currently being negotiated. You will see a difference in protocol versions with some older cipher suites—for example:.
The selected suite could be used with SSL 3. You can also determine that the server has issued to you a session ID and a TLS session ticket a way of resuming sessions without having the server maintain state and that secure renegotiation is supported. Sometimes you will observe less information initially, with additional information arriving later in bursts.
This behavior depends on the implementation and reflects the changes in TLS 1. Additionally, multiple session tickets are usually sent on the same connection. It is equally important that the configured certificate matches the correct DNS names. Further, before you begin to trust its judgment you need to be confident that it can recognize a valid certificate when it sees one.
In the example from the previous section, the verification status code shown on the penultimate line was 0 , which means that the verification has been successful. For example:. If you instead have a single file with the roots in it, use the -CAfile switch:.
Some other protocols start off as plaintext, but then they upgrade to encryption. Provide the protocol information using the - starttls switch. At the time of writing, the supported protocols in recent OpenSSL releases are smtp , pop3 , imap , ftp , xmpp , xmpp-server , irc , postgres , mysql , lmtp , nntp , sieve , and ldap. There is less choice with OpenSSL 1. Some protocols require the client to provide their names.
If you need the certificate for any reason, you can copy it from the scroll-back buffer. If you know in advance you only want to retrieve the certificate, you can use this command line as a shortcut:. With that switch enabled, the previous command line will place all the certificates in the same file. The following command shows detailed server information, along with its SHA fingerprint:.
Sometimes you will need to take the certificate fingerprint and use it with other tools. Unfortunately, OpenSSL outputs certificates in a format that shows individual bytes and separates them using colons.
This handy command line normalizes certificate fingerprints by removing the colons and converting the hexadecimal characters to lowercase:. Instead, invest into writing a couple of shell functions that will package this functionality into easy-to-use commands.
As mentioned earlier, you will find the protocol version in the output twice, and you want the line that explicitly talks about the protocol: If you need to test support for specific protocol versions, you have two options.
Naturally, each switch requires support for a specific protocol version in the testing tool. If you want to exclude a particular protocol from the testing, there is a family of switches that disable protocols e.
Sometimes that may be the better approach. Understanding if a server supports SSL 2. Although servers that support only SSL 2. Another protocol difference is that SSL 2. In that case, although SSL 2. You should treat this situation as misconfiguration. This is because you can effectively test for only one suite at a time; testing for more than cipher suites that are supported by TLS 1. This is a perfect opportunity to use those handy tools that automate the process.
Still, there will be times when you will need to probe servers to determine if they support a particular suite or a cryptographic primitive, or if the preference is correctly configured. The introduction of TLS 1. When testing TLS 1. The output will naturally be different if you pick a suite that is not supported:. As you can see in the previous example, when testing TLS 1. If you want to probe further, you can always tweak the command line to remove the previously negotiated suite:.
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Active Oldest Votes. To get a list of Cipher methos you can use: openssl list-cipher-commands So for example an AES Cipher: openssl enc -aescbc -salt -in file.
Remember Always to read the manual of what you use. Improve this answer. AAlvz AAlvz 3 3 gold badges 12 12 silver badges 21 21 bronze badges. That is a great link. Reading it. When you run something like: openssl passwd -1 MySecret how do you take the resulting hash and get back the face you entered MySecret to begin with? Normally its showed after you create the cypher. It is showed right after finishing the command. Check out this page. Has some usefull tips about the hash you say.
And A Certificate looks like this if you open it when created.. Maybe I am still confused. If I have a txt file that contains a bunch of passwords and I want to replace the plan text passwords in the sheet with shadow style pasword so if someone get their hands on my sheet they dont just get plain text passwords. I would run something like the command in my first comment and get the result.
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