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cmd/puppeth: support authentication via ssh agent #22634

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Apr 27, 2021
Merged

cmd/puppeth: support authentication via ssh agent #22634

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62 changes: 38 additions & 24 deletions cmd/puppeth/ssh.go
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Original file line number Diff line number Diff line change
Expand Up @@ -30,6 +30,7 @@ import (

"github.com/ethereum/go-ethereum/log"
"golang.org/x/crypto/ssh"
"golang.org/x/crypto/ssh/agent"
"golang.org/x/crypto/ssh/terminal"
)

Expand All @@ -43,6 +44,8 @@ type sshClient struct {
logger log.Logger
}

const EnvSSHAuthSock = "SSH_AUTH_SOCK"

// dial establishes an SSH connection to a remote node using the current user and
// the user's configured private RSA key. If that fails, password authentication
// is fallen back to. server can be a string like user:identity@server:port.
Expand Down Expand Up @@ -79,38 +82,49 @@ func dial(server string, pubkey []byte) (*sshClient, error) {
if username == "" {
username = user.Username
}
// Configure the supported authentication methods (private key and password)
var auths []ssh.AuthMethod

path := filepath.Join(user.HomeDir, ".ssh", identity)
if buf, err := ioutil.ReadFile(path); err != nil {
log.Warn("No SSH key, falling back to passwords", "path", path, "err", err)
// Configure the supported authentication methods (ssh agent, private key and password)
var (
auths []ssh.AuthMethod
conn net.Conn
)
if conn, err = net.Dial("unix", os.Getenv(EnvSSHAuthSock)); err != nil {
log.Warn("Unable to dial SSH agent, falling back to private keys", "err", err)
} else {
key, err := ssh.ParsePrivateKey(buf)
if err != nil {
fmt.Printf("What's the decryption password for %s? (won't be echoed)\n>", path)
blob, err := terminal.ReadPassword(int(os.Stdin.Fd()))
fmt.Println()
if err != nil {
log.Warn("Couldn't read password", "err", err)
}
key, err := ssh.ParsePrivateKeyWithPassphrase(buf, blob)
client := agent.NewClient(conn)
auths = append(auths, ssh.PublicKeysCallback(client.Signers))
}
if err != nil {
path := filepath.Join(user.HomeDir, ".ssh", identity)
if buf, err := ioutil.ReadFile(path); err != nil {
log.Warn("No SSH key, falling back to passwords", "path", path, "err", err)
} else {
key, err := ssh.ParsePrivateKey(buf)
if err != nil {
log.Warn("Failed to decrypt SSH key, falling back to passwords", "path", path, "err", err)
fmt.Printf("What's the decryption password for %s? (won't be echoed)\n>", path)
blob, err := terminal.ReadPassword(int(os.Stdin.Fd()))
fmt.Println()
if err != nil {
log.Warn("Couldn't read password", "err", err)
}
key, err := ssh.ParsePrivateKeyWithPassphrase(buf, blob)
if err != nil {
log.Warn("Failed to decrypt SSH key, falling back to passwords", "path", path, "err", err)
} else {
auths = append(auths, ssh.PublicKeys(key))
}
} else {
auths = append(auths, ssh.PublicKeys(key))
}
} else {
auths = append(auths, ssh.PublicKeys(key))
}
}
auths = append(auths, ssh.PasswordCallback(func() (string, error) {
fmt.Printf("What's the login password for %s at %s? (won't be echoed)\n> ", username, server)
blob, err := terminal.ReadPassword(int(os.Stdin.Fd()))
auths = append(auths, ssh.PasswordCallback(func() (string, error) {
fmt.Printf("What's the login password for %s at %s? (won't be echoed)\n> ", username, server)
blob, err := terminal.ReadPassword(int(os.Stdin.Fd()))

fmt.Println()
return string(blob), err
}))
fmt.Println()
return string(blob), err
}))
}
// Resolve the IP address of the remote server
addr, err := net.LookupHost(hostname)
if err != nil {
Expand Down