Hello!
Unfortunately, some of our points still uses blowfish, but we can't
change cipher on all of them once,
so we decided to upgrade servers to 2.4.0 and then , one by one, change
client's ciphers.
Don't know why, but I decided to set default cipher on server to
AES-256-CBC ,
and
ncp-ciphers AES-256-GCM:AES-128-GCM:AES-256-CBC:BF-CBC
so blowfish is in list.
and found that servers successfully uses blowfish for some old clients,
but for others not:
client config has no cipher info, i.e. it is default:
# Select a cryptographic cipher.
# If the cipher option is used on the server
# then you must also specify it here.
;cipher x
But during connection server tries to use AES-256 ( i removed client ip).
Jan 24 13:00:21 inetgw2 openvpn[11265]: :16900 Data Channel Encrypt:
Cipher 'AES-256-CBC' initialized with 256 bit key
Jan 24 13:00:21 inetgw2 openvpn[11265]: :16900 Data Channel Encrypt:
Using 160 bit message hash 'SHA1' for HMAC authentication
Jan 24 13:00:21 inetgw2 openvpn[11265]: :16900 Data Channel Decrypt:
Cipher 'AES-256-CBC' initialized with 256 bit key
Jan 24 13:00:21 inetgw2 openvpn[11265]: :16900 Data Channel Decrypt:
Using 160 bit message hash 'SHA1' for HMAC authentication
Jan 24 13:00:21 inetgw2 openvpn[11265]: :16900 Control Channel: TLSv1,
cipher TLSv1/SSLv3 ECDHE-RSA-AES256-SHA, 1024 bit RSA
this results in fail:
Jan 24 13:00:34 inetgw2 openvpn[11265]: turetskoye:16900
Authenticate/Decrypt packet error: cipher final failed
This is
OpenVPN 2.3.2 i486-unknown-linux-uclibc [SSL (OpenSSL)] [LZO] [EPOLL]
[eurephia] [MH] [IPv6] built on Nov 6 2014
the same problem is for
OpenVPN 2.3.0 arm-buildroot-linux-uclibcgnueabi [SSL (OpenSSL)] [LZO]
[EPOLL] [MH] [IPv6] built on Oct 28 2014
So, for now, I left default cipher on server.
But, according to man servers has to choose blowfish:
" to allow for more smooth transition, if NCP is enabled, OpenVPN
will inherit the cipher of the peer if that cipher is different from the
local --cipher setting, but the peer
cipher is one of the ciphers specified in --ncp-ciphers.
E.g. a non-NCP client (<=2.3, or with --ncp-disabled set) connecting to
a NCP server (2.4+) with "--cipher BF-CBC" and "--ncp-ciphers
AES-256-GCM:AES-256-CBC" set can either specify "--cipher
BF-CBC" or "--cipher AES-256-CBC" and both will work."
Right?
Or what I'm doing wrong?
Thank you!
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