diff --git a/ssh/cipher.go b/ssh/cipher.go
index b0204ee59f..43fd974cb3 100644
--- a/ssh/cipher.go
+++ b/ssh/cipher.go
@@ -116,6 +116,7 @@ var cipherModes = map[string]*cipherMode{
 
 	// AEAD ciphers
 	gcmCipherID:        {16, 12, newGCMCipher},
+	gcm256CipherID:     {32, 12, newGCMCipher},
 	chacha20Poly1305ID: {64, 0, newChaCha20Cipher},
 
 	// CBC mode is insecure and so is not included in the default config.
diff --git a/ssh/common.go b/ssh/common.go
index 290382d059..c11b1ea803 100644
--- a/ssh/common.go
+++ b/ssh/common.go
@@ -27,7 +27,7 @@ const (
 // supportedCiphers lists ciphers we support but might not recommend.
 var supportedCiphers = []string{
 	"aes128-ctr", "aes192-ctr", "aes256-ctr",
-	"aes128-gcm@openssh.com",
+	gcmCipherID, gcm256CipherID,
 	chacha20Poly1305ID,
 	"arcfour256", "arcfour128", "arcfour",
 	aes128cbcID,
@@ -36,7 +36,7 @@ var supportedCiphers = []string{
 
 // preferredCiphers specifies the default preference for ciphers.
 var preferredCiphers = []string{
-	"aes128-gcm@openssh.com",
+	gcmCipherID, gcm256CipherID,
 	chacha20Poly1305ID,
 	"aes128-ctr", "aes192-ctr", "aes256-ctr",
 }
@@ -137,7 +137,7 @@ func (a *directionAlgorithms) rekeyBytes() int64 {
 	// 2^(BLOCKSIZE/4) blocks. For all AES flavors BLOCKSIZE is
 	// 128.
 	switch a.Cipher {
-	case "aes128-ctr", "aes192-ctr", "aes256-ctr", gcmCipherID, aes128cbcID:
+	case "aes128-ctr", "aes192-ctr", "aes256-ctr", gcmCipherID, gcm256CipherID, aes128cbcID:
 		return 16 * (1 << 32)
 
 	}
diff --git a/ssh/transport.go b/ssh/transport.go
index 49ddc2e7de..75e560f75f 100644
--- a/ssh/transport.go
+++ b/ssh/transport.go
@@ -18,6 +18,7 @@ const debugTransport = false
 
 const (
 	gcmCipherID    = "aes128-gcm@openssh.com"
+	gcm256CipherID = "aes256-gcm@openssh.com"
 	aes128cbcID    = "aes128-cbc"
 	tripledescbcID = "3des-cbc"
 )