scp performance

Speed comparison between various ciphers supported by SSH. The test measures the time to copy a file from the client to the server using scp. This script was used to run the tests. I used the linux source code as a test file because it has a reasonable size (about ½ Gig) and can be compressed.

Key findings:

Performance improved a lot over the last 3 years. I'm not sure whether this is because of hardware or software improvements. I'll have to repeat these measurements on old hardware with new SSH versions some day.
In late 2013, only arcfour could saturate a gigabit lan. In early 2017, all algorithms can. The AES variants are all close to 5 Gbit/s.
Chacha20 is much slower than AES, but only if you have faster h
Compression is always a bad idea on a gigabit LAN. It It should be beneficial at speeds below ~ 300 Mbit/s (with fast CPUs).

Client CPU	Intel(R) Xeon(R) CPU E5-2643 v3 @ 3.40GHz
Client SSH	OpenSSH_6.7p1 Debian-5+deb8u3, OpenSSL 1.0.1t 3 May 2016
Server CPU	Intel(R) Xeon(R) CPU E5-2643 v3 @ 3.40GHz
Server SSH	SSH-2.0-OpenSSH_6.7p1 Debian-5+deb8u3
Network	loopback
File	linux-4.9.11.tar (664MiB)
Note

Cipher	Compression	Speed MiB/s	elapsed (min:s)
aes192-ctr		552.5	00:01.2
aes256-gcm@openssh.com		551.7	00:01.2
aes128-gcm@openssh.com		536.1	00:01.2
aes128-ctr		509.6	00:01.3
		497.0	00:01.3
aes256-ctr		488.2	00:01.4
chacha20-poly1305@openssh.com		209.7	00:03.2
aes128-ctr	-C	35.5	00:18.7
aes192-ctr	-C	35.4	00:18.7
aes256-ctr	-C	35.2	00:18.8
aes128-gcm@openssh.com	-C	35.2	00:18.9
	-C	34.9	00:19.0
aes256-gcm@openssh.com	-C	34.7	00:19.1
chacha20-poly1305@openssh.com	-C	33.9	00:19.6

Client CPU	Intel(R) Xeon(R) CPU E5-2643 v3 @ 3.40GHz
Client SSH	OpenSSH_6.7p1 Debian-5+deb8u3, OpenSSL 1.0.1t 3 May 2016
Server CPU	Intel(R) Xeon(R) CPU E5-2643 v3 @ 3.40GHz
Server SSH	SSH-2.0-OpenSSH_6.7p1 Debian-5+deb8u3
Network	1 Gbit/s LAN
File	linux-4.9.11.tar (664MiB)
Note

Cipher	Compression	Speed MiB/s	elapsed (min:s)
aes256-ctr		109.5	00:06.1
aes128-ctr		109.5	00:06.1
		109.5	00:06.1
aes192-ctr		109.5	00:06.1
aes128-gcm@openssh.com		109.4	00:06.1
chacha20-poly1305@openssh.com		109.3	00:06.1
aes256-gcm@openssh.com		109.3	00:06.1
aes128-gcm@openssh.com	-C	36.5	00:18.2
aes256-gcm@openssh.com	-C	36.4	00:18.2
aes128-ctr	-C	36.4	00:18.2
aes256-ctr	-C	36.4	00:18.2
	-C	36.0	00:18.5
aes192-ctr	-C	35.9	00:18.5
chacha20-poly1305@openssh.com	-C	35.6	00:18.7

Client CPU	Intel(R) Core(TM)2 Duo CPU E8400 @ 3.00GHz
Client SSH	OpenSSH_6.0p1 Debian-4, OpenSSL 1.0.1e 11 Feb 2013 (32 bit)
Server CPU	Intel(R) Core(TM)2 CPU 6300 @ 1.86GHz
Server SSH	SSH-2.0-OpenSSH_6.0p1 Debian-4 (32 bit)
Network	WAN connection. Uplink limited to 24 Mbit/s at the client side with traffic shaping. 25/5 Mbit/s cable on server side.
File	linux-3.12.tar (519 MiB)
Note

Cipher	Compression	Speed MiB/s	elapsed (min:s)
aes256-ctr	-C	9.8	00:52.8
aes192-cbc	-C	9.8	00:53.0
arcfour128	-C	9.5	00:54.6
aes256-cbc	-C	9.5	00:54.7
aes128-ctr	-C	9.5	00:54.8
arcfour256	-C	9.2	00:56.4
	-C	9.1	00:56.8
aes192-ctr	-C	9.0	00:57.4
cast128-cbc	-C	8.7	00:59.6
3des-cbc	-C	8.4	01:02.1
arcfour	-C	8.2	01:03.1
blowfish-cbc	-C	7.5	01:09.3
aes128-cbc	-C	7.1	01:12.9
aes128-cbc		2.1	04:04.3
aes192-cbc		2.1	04:05.1
aes256-cbc		2.1	04:07.7
aes128-ctr		2.1	04:09.9
3des-cbc		2.0	04:18.7
arcfour256		1.9	04:26.4
		1.9	04:30.7
arcfour128		1.9	04:31.8
arcfour		1.9	04:40.3
cast128-cbc		1.8	04:47.7
aes192-ctr		1.8	04:49.0
aes256-ctr		1.8	04:50.3
blowfish-cbc		1.8	04:54.9

Client CPU	Intel Atom E6xx [Genuine Intel(R) CPU @ 1.60GHz]
Client SSH	OpenSSH_6.0p1 Debian-4, OpenSSL 1.0.1e 11 Feb 2013 (32 bit)
Server CPU	Intel Atom E6xx [Genuine Intel(R) CPU @ 1.60GHz]
Server SSH	SSH-2.0-OpenSSH_6.0p1 Debian-4 (32 bit)
Network	1 Gbit/s directly connected
File	linux-3.12.tar (519 MiB)
Note

Cipher	Compression	Speed MiB/s	elapsed (min:s)
arcfour256		34.0	00:15.2
arcfour128		34.0	00:15.2
arcfour		33.8	00:15.3
blowfish-cbc		20.8	00:24.9
cast128-cbc		14.5	00:35.7
aes128-cbc		11.0	00:47.4
aes192-cbc		9.5	00:54.4
aes128-ctr		9.3	00:55.6
		9.3	00:55.8
aes256-cbc		8.3	01:02.3
aes192-ctr		8.1	01:03.9
aes256-ctr		7.2	01:12.0
3des-cbc		6.2	01:23.8
arcfour	-C	4.6	01:53.3
arcfour256	-C	4.6	01:53.5
arcfour128	-C	4.6	01:53.5
blowfish-cbc	-C	4.5	01:56.3
cast128-cbc	-C	4.4	01:58.1
aes128-cbc	-C	4.4	01:58.5
aes192-cbc	-C	4.4	01:58.5
aes256-cbc	-C	4.3	02:00.4
aes192-ctr	-C	4.2	02:02.5
	-C	4.2	02:02.8
aes128-ctr	-C	4.2	02:03.0
aes256-ctr	-C	4.1	02:05.1
3des-cbc	-C	4.0	02:09.2

Client CPU	Intel(R) Xeon(R) CPU E5520 @ 2.27GHz
Client SSH	OpenSSH_5.5p1 Debian-6+squeeze3, OpenSSL 0.9.8o 01 Jun 2010 (64 bit)
Server CPU	Intel(R) Xeon(R) CPU E5530 @ 2.40GHz
Server SSH	SSH-2.0-OpenSSH_6.0p1 Debian-4 (64 bit)
Network	1 Gbit/s LAN
File	linux-3.12.tar (519 MiB)
Note

Cipher	Compression	Speed MiB/s	elapsed (min:s)
arcfour		94.0	00:05.5
arcfour256		85.3	00:06.1
aes128-cbc		83.8	00:06.2
arcfour128		82.3	00:06.3
aes192-cbc		77.1	00:06.7
aes256-cbc		71.4	00:07.3
blowfish-cbc		55.1	00:09.4
aes128-ctr		52.9	00:09.8
		52.4	00:09.9
cast128-cbc		51.1	00:10.1
aes192-ctr		46.9	00:11.1
aes256-ctr		41.5	00:12.5
arcfour128	-C	19.9	00:26.1
arcfour	-C	19.8	00:26.2
	-C	19.8	00:26.2
aes192-ctr	-C	19.8	00:26.3
aes256-cbc	-C	19.7	00:26.3
aes128-cbc	-C	19.4	00:26.8
aes192-cbc	-C	19.2	00:27.0
blowfish-cbc	-C	19.2	00:27.0
aes128-ctr	-C	18.8	00:27.6
cast128-cbc	-C	18.7	00:27.7
aes256-ctr	-C	18.6	00:27.8
arcfour256	-C	17.5	00:29.7
3des-cbc		17.3	00:30.0
3des-cbc	-C	16.4	00:31.7

Client CPU	Intel(R) Core(TM)2 Duo CPU E8400 @ 3.00GHz
Client SSH	OpenSSH_6.0p1 Debian-4, OpenSSL 1.0.1e 11 Feb 2013 (32 bit)
Server CPU	Intel(R) Core(TM)2 Duo CPU E8400 @ 3.00GHz
Server SSH	SSH-2.0-OpenSSH_6.0p1 Debian-4
Network	loopback
File	linux-3.12.tar (519 MiB)
Note

Cipher	Compression	Speed MiB/s	elapsed (min:s)
arcfour128		140.3	00:03.7
arcfour		139.0	00:03.7
arcfour256		137.4	00:03.8
aes128-cbc		98.4	00:05.3
aes192-cbc		90.7	00:05.7
aes256-cbc		79.9	00:06.5
blowfish-cbc		69.9	00:07.4
		56.4	00:09.2
aes128-ctr		55.6	00:09.3
cast128-cbc		54.0	00:09.6
aes192-ctr		50.7	00:10.2
aes256-ctr		45.9	00:11.3
3des-cbc		21.5	00:24.2
arcfour128	-C	17.4	00:29.8
arcfour	-C	17.3	00:30.0
arcfour256	-C	17.3	00:30.0
aes128-cbc	-C	17.1	00:30.4
aes192-cbc	-C	17.0	00:30.6
aes256-cbc	-C	16.9	00:30.7
blowfish-cbc	-C	16.5	00:31.4
	-C	16.2	00:32.1
aes128-ctr	-C	16.1	00:32.1
cast128-cbc	-C	16.1	00:32.3
aes192-ctr	-C	15.8	00:32.8
aes256-ctr	-C	15.7	00:33.1
3des-cbc	-C	13.5	00:38.5

The following results were obtained by hand or with a shell script. They may not be directly comparable to the results above.

Client	Intel(R) Xeon(R) CPU E5520 @ 2.27GHz (VMware guest)
Server	Intel(R) Xeon(R) CPU E5520 @ 2.27GHz (VMware guest)
File	5144 MiB gzipped mysql dump
Note	The client was busy at the time, YMMV

Cipher	Speed (MB/s)	elapsed (m:s)
arcfour128	41.5	02:04
aes128-cbc	34.3	02:30
blowfish-cbc	30.3	02:50
default (aes128-ctr?)	26.8	03:12

Client	Intel(R) Core(TM)2 Duo CPU E8400 @ 3.00GHz
Server	Intel(R) Xeon(R) CPU E5-2640 0 @ 2.50GHz (VMware guest)
File	512 MiB 0 filled

Cipher	Speed (MB/s)	elapsed (m:s)
aes128-cbc	73.1	00:07
arcfour128	56.9	00:09
arcfour	56.9	00:09
aes256-cbc	56.9	00:09
aes192-cbc	51.2	00:10
blowfish-cbc	46.6	00:11
arcfour256	46.6	00:11
aes128-ctr	39.4	00:13
aes192-ctr	36.6	00:14
cast128-cbc	34.1	00:15
aes256-ctr	32.0	00:16
3des-cbc	14.6	00:35