Motivation

Raspberry Pi 4 に Rockstor を Install してバックアップ取ってたら 20 [MB/s] とかで遅すぎた
top 見てたら sshd-session の CPU 使用率が 100% に張り付いていたので、暗号処理とか MAC 処理に苦しんでいるのでは？と
nc とか使えばいいじゃん、と思うかもしれないが、複数ファイルの処理とか、他の処理とのコンパチを考えると ssh を使えたほうが嬉しい
- 個人的に ssh/scp/rsync をバックエンドにしてローカルキャッシュとかトランザクション処理を行う Python ライブラリを作っているので、その兼ね合いもある

TL;DR

Cipher も MAC も無効化すると 1GbE の上限 (113 MB/s) くらい出る
Cipher で見ると以下の順で処理が軽い
- none > chacha20-poly1305@openssh.com > aes128-ctr > aes192-ctr > aes256-ctr > aes128-gcm@openssh.com > aes256-gcm@openssh.com
MAC で見ると以下の順で処理が軽い (Cipher に若干の依存がある)
- none > umac-64-etm@openssh.com > umac-128-etm@openssh.com > umac-64@openssh.com > umac-128@openssh.com > hmac-sha2-512-etm@openssh.com > hmac-sha2-512 > hmac-sha1-etm@openssh.com > hmac-sha1 > hmac-sha2-256 > hmac-sha2-256-etm@openssh.com

OpenSSH のビルド

openssh-portable を DL して、「暗復号無効」「MAC 無効」のバイナリを作る

ソースの clone & checkout

% git clone https://github.com/openssh/openssh-portable
% cd openssh-portable
% git checkout V_9_9_P2
Note: switching to 'V_9_9_P2'.

You are in 'detached HEAD' state. You can look around, make experimental
changes and commit them, and you can discard any commits you make in this
state without impacting any branches by switching back to a branch.

If you want to create a new branch to retain commits you create, you may
do so (now or later) by using -c with the switch command. Example:

  git switch -c <new-branch-name>

Or undo this operation with:

  git switch -

Turn off this advice by setting config variable advice.detachedHead to false

HEAD is now at d76b26751 autogenerated files for release

Ciphers "none" 有効化

% git apply enable-ciphers-none.patch

enable-ciphers-none.patch

diff --git a/cipher.c b/cipher.c
index 7d6e7d8c6..a98f6e81d 100644
--- a/cipher.c
+++ b/cipher.c
@@ -121,8 +121,8 @@ cipher_alg_list(char sep, int auth_only)
        const struct sshcipher *c;
 
        for (c = ciphers; c->name != NULL; c++) {
-               if ((c->flags & CFLAG_INTERNAL) != 0)
-                       continue;
+               //if ((c->flags & CFLAG_INTERNAL) != 0)
+               //      continue;
                if (auth_only && c->auth_len == 0)
                        continue;
                if (ret != NULL)
@@ -224,7 +224,7 @@ ciphers_valid(const char *names)
        for ((p = strsep(&cp, CIPHER_SEP)); p && *p != '\0';
            (p = strsep(&cp, CIPHER_SEP))) {
                c = cipher_by_name(p);
-               if (c == NULL || (c->flags & CFLAG_INTERNAL) != 0) {
+               if (c == NULL) { //|| (c->flags & CFLAG_INTERNAL) != 0) {
                        free(cipher_list);
                        return 0;
                }
diff --git a/myproposal.h b/myproposal.h
index 3bdc2e955..d01704296 100644
--- a/myproposal.h
+++ b/myproposal.h
@@ -61,7 +61,8 @@
 #define        KEX_SERVER_ENCRYPT \
        "chacha20-poly1305@openssh.com," \
        "aes128-ctr,aes192-ctr,aes256-ctr," \
-       "aes128-gcm@openssh.com,aes256-gcm@openssh.com"
+       "aes128-gcm@openssh.com,aes256-gcm@openssh.com," \
+       "none"
 
 #define KEX_CLIENT_ENCRYPT KEX_SERVER_ENCRYPT

MACs "none" 有効化

% git apply enable-mac-none.patch

enable-mac-none.patch

diff --git a/mac.c b/mac.c
index f3dda6692..45659f654 100644
--- a/mac.c
+++ b/mac.c
@@ -41,6 +41,7 @@
 
 #include "openbsd-compat/openssl-compat.h"
 
+#define SSH_NOMAC      -1      /* NO MAC */
 #define SSH_DIGEST     1       /* SSH_DIGEST_XXX */
 #define SSH_UMAC       2       /* UMAC (not integrated with OpenSSL) */
 #define SSH_UMAC128    3
@@ -76,6 +77,9 @@ static const struct macalg macs[] = {

+       /* NO MAC */
+       { "none",                               SSH_NOMAC, 0, 0, 0, 0, 0 },
+
        { NULL,                                 0, 0, 0, 0, 0, 0 }
 };
 
@@ -106,7 +110,12 @@ static int
 mac_setup_by_alg(struct sshmac *mac, const struct macalg *macalg)
 {
        mac->type = macalg->type;
-       if (mac->type == SSH_DIGEST) {
+       if (mac->type == SSH_NOMAC) {
+               mac->mac_len = 0;
+               mac->key_len = 0;
+               mac->hmac_ctx = NULL;
+               mac->umac_ctx = NULL;
+       } else if (mac->type == SSH_DIGEST) {
                if ((mac->hmac_ctx = ssh_hmac_start(macalg->alg)) == NULL)
                        return SSH_ERR_ALLOC_FAIL;
                mac->key_len = mac->mac_len = ssh_hmac_bytes(macalg->alg);
@@ -142,6 +151,8 @@ mac_init(struct sshmac *mac)
        if (mac->key == NULL)
                return SSH_ERR_INVALID_ARGUMENT;
        switch (mac->type) {
+       case SSH_NOMAC:
+               return 0;
        case SSH_DIGEST:
                if (mac->hmac_ctx == NULL ||
                    ssh_hmac_init(mac->hmac_ctx, mac->key, mac->key_len) < 0)
@@ -176,6 +187,9 @@ mac_compute(struct sshmac *mac, u_int32_t seqno,
                return SSH_ERR_INTERNAL_ERROR;
 
        switch (mac->type) {
+       case SSH_NOMAC:
+               memset(u.m, 0, sizeof(u.m));
+               break;
        case SSH_DIGEST:
                put_u32(b, seqno);
                /* reset HMAC context */
@@ -214,7 +228,9 @@ mac_check(struct sshmac *mac, u_int32_t seqno,
        u_char ourmac[SSH_DIGEST_MAX_LENGTH];
        int r;
 
-       if (mac->mac_len > mlen)
+       if (mac->type == SSH_NOMAC) {
+               return 0;
+       } else if (mac->mac_len > mlen)
                return SSH_ERR_INVALID_ARGUMENT;
        if ((r = mac_compute(mac, seqno, data, dlen,
            ourmac, sizeof(ourmac))) != 0)
diff --git a/myproposal.h b/myproposal.h
index 3bdc2e955..d01704296 100644
--- a/myproposal.h
+++ b/myproposal.h
@@ -75,7 +76,8 @@
        "umac-128@openssh.com," \
        "hmac-sha2-256," \
        "hmac-sha2-512," \
-       "hmac-sha1"
+       "hmac-sha1," \
+       "none"
 
 #define KEX_CLIENT_MAC KEX_SERVER_MAC

sshd_config 編集 (listen port)

2222 番ポートで起動するように設定

% git apply listen-on-2222.patch
% grep "Port " sshd_config
Port 2222

listen-on-2222.patch

diff --git a/sshd_config b/sshd_config
index 36894ace5..24620675a 100644
--- a/sshd_config
+++ b/sshd_config
@@ -10,7 +10,7 @@
 # possible, but leave them commented.  Uncommented options override the
 # default value.
 
-#Port 22
+Port 2222
 #AddressFamily any
 #ListenAddress 0.0.0.0
 #ListenAddress ::

ビルド

git diff

diff --git a/cipher.c b/cipher.c
index 7d6e7d8c6..a98f6e81d 100644
--- a/cipher.c
+++ b/cipher.c
@@ -121,8 +121,8 @@ cipher_alg_list(char sep, int auth_only)
        const struct sshcipher *c;
 
        for (c = ciphers; c->name != NULL; c++) {
-               if ((c->flags & CFLAG_INTERNAL) != 0)
-                       continue;
+               //if ((c->flags & CFLAG_INTERNAL) != 0)
+               //      continue;
                if (auth_only && c->auth_len == 0)
                        continue;
                if (ret != NULL)
@@ -224,7 +224,7 @@ ciphers_valid(const char *names)
        for ((p = strsep(&cp, CIPHER_SEP)); p && *p != '\0';
            (p = strsep(&cp, CIPHER_SEP))) {
                c = cipher_by_name(p);
-               if (c == NULL || (c->flags & CFLAG_INTERNAL) != 0) {
+               if (c == NULL) { //|| (c->flags & CFLAG_INTERNAL) != 0) {
                        free(cipher_list);
                        return 0;
                }
diff --git a/mac.c b/mac.c
index f3dda6692..45659f654 100644
--- a/mac.c
+++ b/mac.c
@@ -41,6 +41,7 @@
 
 #include "openbsd-compat/openssl-compat.h"
 
+#define SSH_NOMAC      -1      /* NO MAC */
 #define SSH_DIGEST     1       /* SSH_DIGEST_XXX */
 #define SSH_UMAC       2       /* UMAC (not integrated with OpenSSL) */
 #define SSH_UMAC128    3
@@ -76,6 +77,9 @@ static const struct macalg macs[] = {
        { "umac-64-etm@openssh.com",            SSH_UMAC, 0, 0, 128, 64, 1 },
        { "umac-128-etm@openssh.com",           SSH_UMAC128, 0, 0, 128, 128, 1 },
 
+       /* NO MAC */
+       { "none",                               SSH_NOMAC, 0, 0, 0, 0, 0 },
+
        { NULL,                                 0, 0, 0, 0, 0, 0 }
 };
 
@@ -106,7 +110,12 @@ static int
 mac_setup_by_alg(struct sshmac *mac, const struct macalg *macalg)
 {
        mac->type = macalg->type;
-       if (mac->type == SSH_DIGEST) {
+       if (mac->type == SSH_NOMAC) {
+               mac->mac_len = 0;
+               mac->key_len = 0;
+               mac->hmac_ctx = NULL;
+               mac->umac_ctx = NULL;
+       } else if (mac->type == SSH_DIGEST) {
                if ((mac->hmac_ctx = ssh_hmac_start(macalg->alg)) == NULL)
                        return SSH_ERR_ALLOC_FAIL;
                mac->key_len = mac->mac_len = ssh_hmac_bytes(macalg->alg);
@@ -142,6 +151,8 @@ mac_init(struct sshmac *mac)
        if (mac->key == NULL)
                return SSH_ERR_INVALID_ARGUMENT;
        switch (mac->type) {
+       case SSH_NOMAC:
+               return 0;       
        case SSH_DIGEST:
                if (mac->hmac_ctx == NULL ||
                    ssh_hmac_init(mac->hmac_ctx, mac->key, mac->key_len) < 0)
@@ -176,6 +187,9 @@ mac_compute(struct sshmac *mac, u_int32_t seqno,
                return SSH_ERR_INTERNAL_ERROR;
 
        switch (mac->type) {
+       case SSH_NOMAC:
+               memset(u.m, 0, sizeof(u.m));
+               break;
        case SSH_DIGEST:
                put_u32(b, seqno);
                /* reset HMAC context */
@@ -214,7 +228,9 @@ mac_check(struct sshmac *mac, u_int32_t seqno,
        u_char ourmac[SSH_DIGEST_MAX_LENGTH];
        int r;
 
-       if (mac->mac_len > mlen)
+       if (mac->type == SSH_NOMAC) {
+               return 0;
+       } else if (mac->mac_len > mlen)
                return SSH_ERR_INVALID_ARGUMENT;
        if ((r = mac_compute(mac, seqno, data, dlen,
            ourmac, sizeof(ourmac))) != 0)
diff --git a/myproposal.h b/myproposal.h
index 3bdc2e955..d01704296 100644
--- a/myproposal.h
+++ b/myproposal.h
@@ -61,7 +61,8 @@
 #define        KEX_SERVER_ENCRYPT \
        "chacha20-poly1305@openssh.com," \
        "aes128-ctr,aes192-ctr,aes256-ctr," \
-       "aes128-gcm@openssh.com,aes256-gcm@openssh.com"
+       "aes128-gcm@openssh.com,aes256-gcm@openssh.com," \
+       "none"
 
 #define KEX_CLIENT_ENCRYPT KEX_SERVER_ENCRYPT
 
@@ -75,7 +76,8 @@
        "umac-128@openssh.com," \
        "hmac-sha2-256," \
        "hmac-sha2-512," \
-       "hmac-sha1"
+       "hmac-sha1," \
+       "none"
 
 #define KEX_CLIENT_MAC KEX_SERVER_MAC
 
diff --git a/sshd_config b/sshd_config
index 36894ace5..24620675a 100644
--- a/sshd_config
+++ b/sshd_config
@@ -10,7 +10,7 @@
 # possible, but leave them commented.  Uncommented options override the
 # default value.
 
-#Port 22
+Port 2222
 #AddressFamily any
 #ListenAddress 0.0.0.0
 #ListenAddress ::

% sudo apt install automake autoconf libssl-dev

% INSTALLDIR=/opt/nssh
% sudo rm -rf ${INSTALLDIR}
% sudo mkdir -p ${INSTALLDIR}
% autoreconf
% ./configure --prefix=${INSTALLDIR}
% make
% sudo make install

% tree /opt/nssh
/opt/nssh
├── bin
│   ├── scp
│   ├── sftp
│   ├── ssh
│   ├── ssh-add
│   ├── ssh-agent
│   ├── ssh-keygen
│   └── ssh-keyscan
├── etc
│   ├── moduli
│   ├── ssh_config
│   ├── ssh_host_ecdsa_key
│   ├── ssh_host_ecdsa_key.pub
│   ├── ssh_host_ed25519_key
│   ├── ssh_host_ed25519_key.pub
│   ├── ssh_host_rsa_key
│   ├── ssh_host_rsa_key.pub
│   └── sshd_config
├── lib
│   ├── sftp-server
│   ├── ssh-keysign
│   ├── ssh-pkcs11-helper
│   ├── ssh-sk-helper
│   └── sshd-session
├── sbin
│   └── sshd
└── share
    └── man
        ├── cat1
        │   ├── scp.1
        │   ├── sftp.1
        │   ├── ssh-add.1
        │   ├── ssh-agent.1
        │   ├── ssh-keygen.1
        │   ├── ssh-keyscan.1
        │   └── ssh.1
        ├── cat5
        │   ├── moduli.5
        │   ├── ssh_config.5
        │   └── sshd_config.5
        └── cat8
            ├── sftp-server.8
            ├── ssh-keysign.8
            ├── ssh-pkcs11-helper.8
            ├── ssh-sk-helper.8
            └── sshd.8

9 directories, 37 files

sshd 起動

sshd は絶対パスで指定される必要アリ

% sudo /opt/nssh/sbin/sshd -f /opt/nssh/etc/sshd_config

性能測定

サーバ側 $
- Raspberry Pi4 / 8GB
- nssh (openssh-portable V_9_9_P2)
クライアント側 %
- NUC8i3BEH
- nssh (openssh-portable V_9_9_P2)
計測コマンド

% dd if=/dev/random of=/tmp/in.img bs=4K count=512K
% cat /tmp/in.img | /opt/nssh/bin/ssh -c <cipher> -m <mac> -p 2222 rpi4 'dd of=/dev/null'

計測結果

cipher	mac	Throughput (min) [MB/s]	Throughput (mean) [MB/s]	Throughput (MAX) [MB/s]
aes128-ctr	hmac-sha1	45.2	50.08	60.9
aes128-ctr	hmac-sha2-256	46.0	49.02	51.3
aes128-ctr	hmac-sha2-512	48.3	55.58	60.8
aes128-ctr	umac-64@openssh.com	66.5	73.18	77.7
aes128-ctr	umac-128@openssh.com	60.2	70.92	77.7
aes128-ctr	hmac-sha1-etm@openssh.com	50.1	54.94	60.5
aes128-ctr	hmac-sha2-256-etm@openssh.com	42.7	47.66	54.9
aes128-ctr	hmac-sha2-512-etm@openssh.com	52.6	56.9	60.6
aes128-ctr	umac-64-etm@openssh.com	68.0	77.6	81.2
aes128-ctr	umac-128-etm@openssh.com	59.4	73.78	79.6
aes128-ctr	none	81.3	83.62	85.0
aes192-ctr	hmac-sha1	50.0	54.68	56.8
aes192-ctr	hmac-sha2-256	46.1	48.98	51.3
aes192-ctr	hmac-sha2-512	43.2	50.12	55.4
aes192-ctr	umac-64@openssh.com	64.8	69.32	72.6
aes192-ctr	umac-128@openssh.com	64.8	67.46	69.4
aes192-ctr	hmac-sha1-etm@openssh.com	49.0	52.58	56.4
aes192-ctr	hmac-sha2-256-etm@openssh.com	43.8	47.7	51.0
aes192-ctr	hmac-sha2-512-etm@openssh.com	52.9	54.12	55.5
aes192-ctr	umac-64-etm@openssh.com	60.5	65.96	70.8
aes192-ctr	umac-128-etm@openssh.com	54.3	64.08	69.1
aes192-ctr	none	70.0	73.82	75.8
aes256-ctr	hmac-sha1	48.2	49	50.4
aes256-ctr	hmac-sha2-256	43.0	44.18	45.5
aes256-ctr	hmac-sha2-512	44.3	50.7	54.7
aes256-ctr	umac-64@openssh.com	50.7	57.6	63.4
aes256-ctr	umac-128@openssh.com	58.5	61.48	63.8
aes256-ctr	hmac-sha1-etm@openssh.com	44.9	48.86	50.7
aes256-ctr	hmac-sha2-256-etm@openssh.com	37.7	43.66	47.6
aes256-ctr	hmac-sha2-512-etm@openssh.com	47.7	49.78	51.6
aes256-ctr	umac-64-etm@openssh.com	54.5	59.54	63.0
aes256-ctr	umac-128-etm@openssh.com	57.1	59.4	63.5
aes256-ctr	none	59.3	63.16	66.7
aes128-gcm@openssh.com	hmac-sha1	46.8	48.36	50.2
aes128-gcm@openssh.com	hmac-sha2-256	45.6	48.74	51.1
aes128-gcm@openssh.com	hmac-sha2-512	48.8	49.72	50.4
aes128-gcm@openssh.com	umac-64@openssh.com	48.0	48.82	50.5
aes128-gcm@openssh.com	umac-128@openssh.com	46.7	49.22	50.6
aes128-gcm@openssh.com	hmac-sha1-etm@openssh.com	46.6	48.54	49.9
aes128-gcm@openssh.com	hmac-sha2-256-etm@openssh.com	44.8	48.94	50.3
aes128-gcm@openssh.com	hmac-sha2-512-etm@openssh.com	46.9	48.5	49.5
aes128-gcm@openssh.com	umac-64-etm@openssh.com	40.6	47.18	50.7
aes128-gcm@openssh.com	umac-128-etm@openssh.com	48.1	49.24	50.3
aes128-gcm@openssh.com	none	45.0	47.86	50.4
aes256-gcm@openssh.com	hmac-sha1	41.9	43.24	44.1
aes256-gcm@openssh.com	hmac-sha2-256	42.8	43.9	44.7
aes256-gcm@openssh.com	hmac-sha2-512	40.7	42.36	43.8
aes256-gcm@openssh.com	umac-64@openssh.com	40.5	42.66	44.3
aes256-gcm@openssh.com	umac-128@openssh.com	41.3	43.2	44.1
aes256-gcm@openssh.com	hmac-sha1-etm@openssh.com	42.0	43.46	44.4
aes256-gcm@openssh.com	hmac-sha2-256-etm@openssh.com	40.9	43.2	44.4
aes256-gcm@openssh.com	hmac-sha2-512-etm@openssh.com	40.8	42.7	44.4
aes256-gcm@openssh.com	umac-64-etm@openssh.com	40.1	42.5	44.5
aes256-gcm@openssh.com	umac-128-etm@openssh.com	41.4	43.64	44.8
aes256-gcm@openssh.com	none	39.0	42.42	44.9
chacha20-poly1305@openssh.com	hmac-sha1	76.5	84.44	97.2
chacha20-poly1305@openssh.com	hmac-sha2-256	77.1	81.52	87.3
chacha20-poly1305@openssh.com	hmac-sha2-512	75.2	85.4	94.3
chacha20-poly1305@openssh.com	umac-64@openssh.com	78.1	89.14	102
chacha20-poly1305@openssh.com	umac-128@openssh.com	74.4	81.3	95.3
chacha20-poly1305@openssh.com	hmac-sha1-etm@openssh.com	79.8	84.22	92.2
chacha20-poly1305@openssh.com	hmac-sha2-256-etm@openssh.com	79.6	85.44	89.7
chacha20-poly1305@openssh.com	hmac-sha2-512-etm@openssh.com	72.6	78.94	83.5
chacha20-poly1305@openssh.com	umac-64-etm@openssh.com	74.7	83.08	89.7
chacha20-poly1305@openssh.com	umac-128-etm@openssh.com	75.7	83.02	89.9
chacha20-poly1305@openssh.com	none	78.8	83.22	85.7
none	hmac-sha1	88.0	99.12	111
none	hmac-sha2-256	82.1	89.64	94.1
none	hmac-sha2-512	75.7	81.28	96.5
none	umac-64@openssh.com	89.1	93.52	95.7
none	umac-128@openssh.com	88.4	92.04	95.8
none	hmac-sha1-etm@openssh.com	91.9	98.8	103
none	hmac-sha2-256-etm@openssh.com	76.6	90.48	95.0
none	hmac-sha2-512-etm@openssh.com	77.7	80.82	82.9
none	umac-64-etm@openssh.com	87.2	91.08	95.2
none	umac-128-etm@openssh.com	90.2	92.96	100
none	none	95.4	102.84	113