Lots of work on making easier interactive documentation, especially to make working with SSH public keys really easy.
Next step is to do more validation in the UI. Specifically: * validate authorized keys * detection of accidental use of a private key Then, password based access can be disabled.
This commit is contained in:
parent
49db7578a7
commit
b41317c598
@ -28,4 +28,4 @@ COPY --from=builder /opt/converge/bin/agent \
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/opt/converge/static/
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COPY --from=builder /opt/converge/static/ /opt/converge/static/
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ENTRYPOINT ["/opt/converge/bin/converge", "-d", "/opt/converge/static" ]
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ENTRYPOINT ["/opt/converge/bin/converge", "-s", "/opt/converge/static", "-d", "/opt/converge/static" ]
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@ -48,14 +48,16 @@ func printHelp(msg string) {
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"an embedded SSH server to provide interactive access to the end-user. This works\n" +
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"both on linux and on windows.\n" +
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"\n" +
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"-d <contentdir>: directory where static content of converge is placed"
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"-s <contentdir>: directory where static content of converge is placed\n" +
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"-d <downloaddir>: directory where downloads of converge are placed\n"
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fmt.Fprintln(os.Stderr, helpText)
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os.Exit(1)
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}
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func main() {
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downloadDir := "../static"
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downloaddir := "."
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staticdir := "../static"
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args := os.Args[1:]
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for len(args) > 0 && strings.HasPrefix(args[0], "-") {
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@ -64,14 +66,20 @@ func main() {
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if len(args) <= 1 {
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printHelp("The -d option expects an argument")
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}
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downloadDir = args[1]
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downloaddir = args[1]
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args = args[1:]
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case "-s":
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if len(args) <= 1 {
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printHelp("The -s option expects an argument")
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}
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staticdir = args[1]
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args = args[1:]
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default:
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printHelp("Unknown option " + args[0])
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}
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args = args[1:]
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}
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log.Println("Content directory", downloadDir)
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log.Println("Content directory", staticdir)
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if len(args) != 0 {
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printHelp("")
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@ -158,7 +166,9 @@ func main() {
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// create filehandler with templating for html files.
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http.Handle("/docs/", http.StripPrefix("/docs/", http.HandlerFunc(pageHandler)))
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http.Handle("/static/", http.StripPrefix("/static/",
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http.FileServer(http.Dir(downloadDir))))
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http.FileServer(http.Dir(staticdir))))
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http.Handle("/downloads/", http.StripPrefix("/downloads/",
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http.FileServer(http.Dir(downloaddir))))
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http.HandleFunc("/", catchAllHandler)
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// create usage generator
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@ -2,16 +2,14 @@ package main
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import (
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"converge/pkg/server/templates"
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"log"
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"math/rand"
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"net/http"
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"os"
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"strconv"
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"strings"
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)
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func generateCLIExammple(w http.ResponseWriter, r *http.Request) {
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log.Println("usage: got ", r.URL.Path)
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err := r.ParseForm()
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if err != nil {
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http.Error(w, "Error parsing form", http.StatusBadRequest)
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@ -27,14 +25,17 @@ func generateCLIExammple(w http.ResponseWriter, r *http.Request) {
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}
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remoteShells := r.Form["remote-shell"]
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localShells := r.Form["local-shell"]
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keys := r.FormValue("ssh-keys")
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log.Printf("remote_shells %v", remoteShells)
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log.Printf("local_shells %v", localShells)
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log.Printf("ssh-keys %v", keys)
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keysString := r.FormValue("ssh-keys")
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sshPublicKeys := make([]string, 0)
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for _, line := range strings.Split(keysString, "\n") {
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line := strings.TrimSpace(line)
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if line != "" {
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sshPublicKeys = append(sshPublicKeys, line)
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}
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}
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access := getConvergeAccess(r, getAgentSshUser())
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usageInputs := templates.NewUsageInputs(id, remoteShells, localShells)
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usageInputs := templates.NewUsageInputs(id, sshPublicKeys, remoteShells, localShells)
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err = templates.ShellUsage(access, usageInputs).Render(r.Context(), w)
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if err != nil {
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http.Error(w, err.Error(), 500)
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@ -19,55 +19,123 @@ templ About() {
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the client and server together.
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</p>
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<h2>other tools</h2>
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<p>Using available existing tools such as
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<a href="https://github.com/namespacelabs/breakpoint">breakpoint</a> in combination
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with a websocket tunneling tool such as
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<a href="https://github.com/erebe/wstunnel">wstunnel</a> a similar solution can be
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obtained. There are however some problems with these solutions that converge is
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trying to address:
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</p>
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<p>
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<ul>
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<li>deployment: Breakpoint uses an embedded SSH server which is a really good idea but
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uses the QUIC protocol for connecting to a rendez-vous server. The rendez-vous server than
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exposes a random port for every client. This make deployment on kubernetes really hard
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where fixed ports must be used and QUIC is also not a widely supported protocol.</li>
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<li>The problem with the random ports can be solved by using wstunnel running together
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with breakpoint server in a kubernetes pod, where wstunnel can forward traffic over an
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extern websocket connection to the local random port that breakpoint server is listening on.</li>
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<li>breakpoint leaves it open on how users install the breakpoint executable (agent). </li>
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<li>Because of the hacky nature of this setup, it is very difficult for users to use
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and troubleshoot when things go wrong. </li>
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</ul>
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</p>
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Converve server addresses these issues in the following ways:
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<ul>
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<li>Use the websocket protocol both for agents and for clients, providing a fixed port and
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a supported protocol for kubernetes deploymment.</li>
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<li>Providing online documentation where the instructions take into account the
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hostname and protocol where converge is running allowing users to cut and paste
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instructions that can be used without modification. In the usage page the users
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can even generate the correct agent startup commands and client connection commands
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based on the type of shell they are connecting to. </li>
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<li>Converge server provides out of the box downloads of required software. This makes sure
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client and server are always up to date. In addition a protocol version check is done. </li>
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<li>User-friendly error messages can be given to users in most case when things do not work
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out because of <code>wsproxy</code>, an SSH proxy command that also talk to the server
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to tell the user if a connection is accepted and if not why not. </li>
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<li>A live screen showing the current sessions that are running. </li>
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<li>Interactivity in the user's session with notifications about timeouts and a very
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simple inactivity timmeout mechanism. </li>
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<li>Possibility for the user to define his own shell. </li>
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<li>Support for unix like bash shells and command prompt and powershell. </li>
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</ul>
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<p>
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</p>
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<h2>how it works</h2>
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<p>
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The steps involved are as follows:
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<ul>
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<li>The agent connects to converge server. If no id is specified than a new id will
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be generated. The ids specified by different agents must be unique. If the agent
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specifies an id that is already in use, then a new id will be generated.
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When started the agent will echo the commands to connect to it in its output.
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</li>
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<li>
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Since the emmbedded SSH server in the agent will allow multiple clients to connect
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to it, it wants to listen for copnnections. By default it cannot do this, it just
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setup a connection to the converge server, but the converge server can in general
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not connect back to it because of networking. Therefore, a multiplexing library is
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used to establish multiple virtual connections over a single TCP connection.
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The agent can now listen for connections from clients.
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</li>
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<li>The agent connects to the converge server using the commmand specified by the agent.
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The converge server can then match the agent with the client based on the id and
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the connectio at network level is established.
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</li>
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<li>The embedded SSH server now performs authentication, after successful login,
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a shell is spwaned and the network connection of the user is connected to it.
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The connection is practically identical to a regular terminal connection. To
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achieve this some magic is used to make the shell beiieve it is connected to a
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terminal.
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</li>
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</ul>
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</p>
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<h2>Security</h2>
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<p>
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The setup is such that the connection from client (end-user) to server (agent on CI job)
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is end-to-end encrypted. The Converge server itself is no more than a bitpipe which pumps
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data between client and agent.
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</p>
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<p>Currently converge server still supports password based login but this will be disabled.
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Image two people configuring an agent with the same id where one of the agents actually
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gets it and other gets a new id. Now, with a password each user can access each other's
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agents. This is of course highly confusing and undesirable. Converge server already support
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authorized keys but this is not yet mandatory. I is made extremely easy through the
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<a href="usage.html">usage</a> page to configure this, so the additional complexity should
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not be an issue.
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</p>
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<h2>SSH and SFTP</h2>
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<p>
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Both ssh and sftp are supported. Multiple shells are also allowed.
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</p>
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<h2>Timeouts</h2>
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<p>
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There is a timeout mechanism in the agent such that jobs do not hang indefinitely
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waiting for a connection. This mechanism is useful to make sure build agents do not keep
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build agents occupied for a long time. By default, the agent exits with status 0 when
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the first client exits after logging in. This behavior as well as general expiry can be
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controlled from within a shell session by touching a .hold file. After logging in, the
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user can control expiry of the session as instructed by messages in the ssh session.
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When the timeout of a session is near the user is informed about this with messages
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in the shell.
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the first client exits after logging in.
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</p>
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<p>end-to-end encryoption</p>
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<p> ssh keys</p>
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<p>agent options </p>
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<p>client access </p>
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<h2>Local clients: using ssh with a proxy command </h2>
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<p>
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<code>wsproxy</code> is a command that can be used as a proxy command for SSH which performs the connection to the
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remote server. This command needs to be downloaded only once (see <a href="downloads.html">downloads</a>). It does not depend on
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the converge implementation but only on the websocket standards. Other tools that
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provide a mapping of stdio to a websocket can also be used instead of wsproxy.
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<p>When the user touches a .hold file, the agent keeps waiting for connections even
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after the last client logs out, taking into account the timeout.
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</p>
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<p>The sessions have an inactivity timeout. Any keypress on the keyboard by a user
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is interpreted as activity. </p>
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<h2>Local clients: using SSH with a local TCP forwarding proxy</h2>
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<p>
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This option is less convenient than the proxy command because it requires two separate
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commands to execute.
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</p>
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<p>
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Local clients can connect using regular ssh and sftp commands through a tunnel that
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translates a local TCP port to a websocket connection in converge. See
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the <a href="downloads.html">downloads</a> section.
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This runs a local client that allows SSH to port 10000 and connects to converge using
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a websocket connection.
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</p>
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<h2>Remote shell usage</h2>
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@ -17,20 +17,20 @@ templ Downloads() {
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</thead>
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<tr>
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<td>agent</td>
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<td><a href="../static/agent">agent</a></td>
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<td><a href="../static/agent.exe">agent.exe</a></td>
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<td><a href="../downloads/agent">agent</a></td>
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<td><a href="../downloads/agent.exe">agent.exe</a></td>
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<td>The agent to run inside aa CI job</td>
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</tr>
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<tr>
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<td>wsproxy</td>
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<td><a href="../static/wsproxy">wsproxy</a></td>
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<td><a href="../static/wsproxy.exe">wsproxy.exe</a></td>
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<td><a href="../downloads/wsproxy">wsproxy</a></td>
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<td><a href="../downloads/wsproxy.exe">wsproxy.exe</a></td>
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<td>SSH proxy command that can be directly used by ssh</td>
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</tr>
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<tr>
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<td>tcptows</td>
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<td><a href="../static/tcptows">tcptows</a></td>
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<td><a href="../static/tcptows.exe">tcptows.exe</a></td>
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<td><a href="../downloads/tcptows">tcptows</a></td>
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<td><a href="../downloads/tcptows.exe">tcptows.exe</a></td>
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<td>You typically do not need to download this.
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It was used for testing at the beginning and can still be used
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as a generic TCP to WS tunnel for allowing regular
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@ -12,16 +12,23 @@ templ AgentUsage(access models.ConvergeAccess, shells map[string]bool, usageInpu
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</p>
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if shells[BASH] {
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<pre>{`
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`}curl http{access.Secure}://{access.HostPort}/static/agent > agent{`
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<pre>{addSshKeys(BASH, usageInputs.SshKeys)}
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curl --fail-with-body http{access.Secure}://{access.HostPort}/downloads/agent > agent{`
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chmod 755 agent
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`}./agent --id {usageInputs.Id} ws{access.Secure}://{access.HostPort}{`
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rm -f agent
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`}</pre>
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}
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if shells[CMD] || shells[POWERSHELL] {
|
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<pre>{`
|
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`}curl http{access.Secure}://{access.HostPort}/static/agent.exe > agent.exe{`
|
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if shells[CMD] {
|
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<pre>{addSshKeys(CMD, usageInputs.SshKeys)}
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curl --fail-with-body http{access.Secure}://{access.HostPort}/downloads/agent.exe > agent.exe{`
|
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`}agent --id {usageInputs.Id} ws{access.Secure}://{access.HostPort}{`
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del agent.exe
|
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`}</pre>
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}
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if shells[POWERSHELL] {
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<pre>{addSshKeys(POWERSHELL, usageInputs.SshKeys)}
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curl --fail-with-body http{access.Secure}://{access.HostPort}/downloads/agent.exe > agent.exe{`
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`}agent --id {usageInputs.Id} ws{access.Secure}://{access.HostPort}{`
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del agent.exe
|
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`}</pre>
|
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@ -41,11 +48,41 @@ templ AgentUsage(access models.ConvergeAccess, shells map[string]bool, usageInpu
|
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|
||||
<h2>Connecting to the agent</h2>
|
||||
|
||||
<p>The embedded ssh server in the agent supports both ssh and sftp. The user name is fixed
|
||||
at <code>{ access.Username }</code>. This is the user used to connect to the embedded
|
||||
SSH server, after logging in however you will be running in a shell that is started
|
||||
by the same user that started the agent.
|
||||
</p>
|
||||
|
||||
<pre>{`
|
||||
`}ssh -oServerAliveInterval=10 -oProxyCommand="wsproxy ws{access.Secure}://{access.HostPort}/client/{usageInputs.Id}" { access.Username }{"@localhost"} {`
|
||||
`}sftp -oServerAliveInterval=10 -oProxyCommand="wsproxy ws{access.Secure}://{access.HostPort}/client/{usageInputs.Id}" { access.Username }{"@localhost"} {`
|
||||
`}</pre>
|
||||
|
||||
<p>This requires the <code>wsproxy</code> utility which is available in the
|
||||
<a href="downloads.html">downloads</a> section. This utility must be downloaded
|
||||
only once since it is quite generic. It will warn you when it a newer version must
|
||||
be downloaded.
|
||||
</p>
|
||||
|
||||
<p>For other ssh clients that do not support the openssh ProxyCommand option, there is another
|
||||
way to connect. In this method, a local port forwarder is started that forwards a local port
|
||||
to the webserver. Then you can start an ssh client that connects to the local tcp port.
|
||||
</p>
|
||||
<pre>{`
|
||||
`}ssh -oServerAliveInterval=10 -p 10000 { access.Username }{"@localhost"} {`
|
||||
`}sftp -oServerAliveInterval=10 -p 10000 { access.Username }{"@localhost"} {`
|
||||
`}</pre>
|
||||
|
||||
<p>This requires the <code>tcptows</code> utility which is available in the
|
||||
<a href="downloads.html">downloads</a> section. The utility must be started beforehand
|
||||
using:
|
||||
</p>
|
||||
<pre>{`
|
||||
`}tcptows ws{access.Secure}://{access.HostPort}/client/{usageInputs.Id} {`
|
||||
`}tcptows ws{access.Secure}://{access.HostPort}/client/{usageInputs.Id} {`
|
||||
`}</pre>
|
||||
|
||||
<h2>Working with the agent</h2>
|
||||
|
||||
if shells[BASH] {
|
||||
@ -90,25 +127,11 @@ templ AgentUsage(access models.ConvergeAccess, shells map[string]bool, usageInpu
|
||||
</div>
|
||||
}
|
||||
|
||||
templ LocalShellUsage(access models.ConvergeAccess, shells map[string]bool, usageInput UsageInputs) {
|
||||
<div>
|
||||
if shells[BASH] {
|
||||
<p>bash</p>
|
||||
}
|
||||
if shells[CMD] {
|
||||
<p>cmd</p>
|
||||
}
|
||||
if shells[POWERSHELL] {
|
||||
<p>powershell</p>
|
||||
}
|
||||
</div>
|
||||
}
|
||||
|
||||
templ ShellUsage(access models.ConvergeAccess, usageInputs UsageInputs) {
|
||||
<div>
|
||||
@AgentUsage(access, usageInputs.RemoteShells, usageInputs)
|
||||
</div>
|
||||
@LocalShellUsage(access, usageInputs.LocalShells, usageInputs)
|
||||
}
|
||||
|
||||
|
||||
@ -163,25 +186,6 @@ templ Usage(access models.ConvergeAccess) {
|
||||
|
||||
<div id="example-cli">
|
||||
</div>
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
<pre> {`
|
||||
`}# linux {`
|
||||
`}echo "ssh-rsa dkddkdkkk a@b.c" > .authorized_keys {`
|
||||
`}echo "ssh-rsa adfadjfdf d@e.f" >> .authorized_keys {`
|
||||
`} {`
|
||||
`}# windows {`
|
||||
`}echo ssh-rsa dkddkdkkk a@b.c > .authorized_keys {`
|
||||
`}echo ssh-rsa adfadjfdf d@e.f >> .authorized_keys
|
||||
</pre>
|
||||
<p>
|
||||
Note that on windows you should not used quotes.
|
||||
</p>
|
||||
|
||||
|
||||
<script>
|
||||
function setCookie(name, value, days) {
|
||||
let expires = "";
|
||||
@ -274,8 +278,8 @@ templ Usage(access models.ConvergeAccess) {
|
||||
document.getElementById('inputs').addEventListener('change', saveFormToCookie);
|
||||
|
||||
document.body.addEventListener('htmx:load', function(event) {
|
||||
//console.log("htmx:load")
|
||||
//loadFormFromCookie();
|
||||
console.log("htmx:load")
|
||||
loadFormFromCookie();
|
||||
});
|
||||
|
||||
document.body.addEventListener('htmx:afterSettle', function(event) {
|
||||
|
||||
@ -1,5 +1,9 @@
|
||||
package templates
|
||||
|
||||
import (
|
||||
"fmt"
|
||||
)
|
||||
|
||||
type UsageInputs struct {
|
||||
Id string
|
||||
SshKeys []string
|
||||
@ -7,9 +11,10 @@ type UsageInputs struct {
|
||||
LocalShells map[string]bool
|
||||
}
|
||||
|
||||
func NewUsageInputs(id string, remoteShells []string, localShells []string) UsageInputs {
|
||||
func NewUsageInputs(id string, sshPublicKeys []string, remoteShells []string, localShells []string) UsageInputs {
|
||||
inputs := UsageInputs{
|
||||
Id: id,
|
||||
SshKeys: sshPublicKeys,
|
||||
RemoteShells: make(map[string]bool),
|
||||
LocalShells: make(map[string]bool),
|
||||
}
|
||||
@ -21,3 +26,20 @@ func NewUsageInputs(id string, remoteShells []string, localShells []string) Usag
|
||||
}
|
||||
return inputs
|
||||
}
|
||||
|
||||
func addSshKeys(shell string, keys []string) string {
|
||||
quote := `"`
|
||||
if shell == CMD {
|
||||
quote = ""
|
||||
}
|
||||
res := ""
|
||||
for index, key := range keys {
|
||||
operator := ">>"
|
||||
if index == 0 {
|
||||
operator = ">"
|
||||
}
|
||||
res += fmt.Sprintf(" echo %s%s%s %s .authorized_keys\n", quote, key, quote,
|
||||
operator)
|
||||
}
|
||||
return res + " "
|
||||
}
|
||||
|
||||
Loading…
Reference in New Issue
Block a user