Wonderland

Usually, X11 forwarding is slow. However, we can choose some options to make it faster.

1. choose an appropriate cipher specification for encrypting the session

Here is a benchmark done in Ubuntu bug report (#54180)

$ for c in 3des-cbc aes128-cbc aes192-cbc aes256-cbc aes128-ctr aes192-ctr \
aes256-ctr arcfour128 arcfour256 arcfour blowfish-cbc cast128-cbc; \
do echo using cipher $c; ssh -c $c localhost dd if=/dev/zero bs=32k \
count=10000 >/dev/null; done

results:

 3des-cbc	22.6 MB/s
 aes128-cbc	63.8 MB/s
 aes192-cbc	67.6 MB/s
 aes256-cbc	67.4 MB/s
 aes128-ctr	74.9 MB/s
 aes192-ctr	73.6 MB/s
 aes256-ctr	73.3 MB/s
 arcfour128	109 MB/s
 arcfour256	108 MB/s
 arcfour	107 MB/s
 blowfish-cbc	75.0 MB/s
 cast128-cbc	62.0 MB/s

2. choose an appropriate MAC (message authentication code) algorithms

Here is also a benchmark

$ for m in hmac-md5 hmac-sha1 umac-64 hmac-ripemd160; \
do echo using digest $m; ssh -c arcfour128 -m $m localhost \
dd if=/dev/zero bs=32k count=10000 >/dev/null; done

results:

 hmac-md5	108 MB/s
 hmac-sha1	97.9 MB/s
 hmac-ripemd160	83.0 MB/s

3. enable compression

For example, you can establish a much faster connection for X11 forwarding by using

ssh -c arcfour,blowfish-cbc -m hmac-md5 -XC