ssh: remove arcfour ciphers from the default preference list
OpenSSH removed these ciphers from sshd's default configuration with
release 6.7 in 2014.
Change-Id: Ia8b6d671dc8fa5d0493bf933d3b541f8ae5707a3
Reviewed-on: https://go-review.googlesource.com/86955
Run-TryBot: Han-Wen Nienhuys <hanwen@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Adam Langley <agl@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
diff --git a/ssh/cipher_test.go b/ssh/cipher_test.go
index 6a35d87..6da5815 100644
--- a/ssh/cipher_test.go
+++ b/ssh/cipher_test.go
@@ -15,7 +15,12 @@
func TestDefaultCiphersExist(t *testing.T) {
for _, cipherAlgo := range supportedCiphers {
if _, ok := cipherModes[cipherAlgo]; !ok {
- t.Errorf("default cipher %q is unknown", cipherAlgo)
+ t.Errorf("supported cipher %q is unknown", cipherAlgo)
+ }
+ }
+ for _, cipherAlgo := range preferredCiphers {
+ if _, ok := cipherModes[cipherAlgo]; !ok {
+ t.Errorf("preferred cipher %q is unknown", cipherAlgo)
}
}
}
diff --git a/ssh/common.go b/ssh/common.go
index 77f9c5b..ffdc01f 100644
--- a/ssh/common.go
+++ b/ssh/common.go
@@ -24,12 +24,21 @@
serviceSSH = "ssh-connection"
)
-// supportedCiphers specifies the supported ciphers in preference order.
+// supportedCiphers lists ciphers we support but might not recommend.
var supportedCiphers = []string{
"aes128-ctr", "aes192-ctr", "aes256-ctr",
"aes128-gcm@openssh.com",
chacha20Poly1305ID,
- "arcfour256", "arcfour128",
+ "arcfour256", "arcfour128", "arcfour",
+ aes128cbcID,
+ tripledescbcID,
+}
+
+// preferredCiphers specifies the default preference for ciphers.
+var preferredCiphers = []string{
+ "aes128-ctr", "aes192-ctr", "aes256-ctr",
+ "aes128-gcm@openssh.com",
+ chacha20Poly1305ID,
}
// supportedKexAlgos specifies the supported key-exchange algorithms in
@@ -212,7 +221,7 @@
c.Rand = rand.Reader
}
if c.Ciphers == nil {
- c.Ciphers = supportedCiphers
+ c.Ciphers = preferredCiphers
}
var ciphers []string
for _, c := range c.Ciphers {
diff --git a/ssh/test/session_test.go b/ssh/test/session_test.go
index 9e702ef..7588b0c 100644
--- a/ssh/test/session_test.go
+++ b/ssh/test/session_test.go
@@ -324,13 +324,15 @@
}
}
+var deprecatedCiphers = []string{
+ "aes128-cbc", "3des-cbc",
+ "arcfour128", "arcfour256",
+}
+
func TestCiphers(t *testing.T) {
var config ssh.Config
config.SetDefaults()
- cipherOrder := config.Ciphers
- // These ciphers will not be tested when commented out in cipher.go it will
- // fallback to the next available as per line 292.
- cipherOrder = append(cipherOrder, "aes128-cbc", "3des-cbc")
+ cipherOrder := append(config.Ciphers, deprecatedCiphers...)
for _, ciph := range cipherOrder {
t.Run(ciph, func(t *testing.T) {
