Hi, On Mon, Feb 15, 2021 at 03:31:46PM +0100, Arne Schwabe wrote: > Modern TLS libraries might drop Blowfish by default or distributions > might disable Blowfish in OpenSSL/mbed TLS. We still signal OCC > options with BF-CBC compatible strings. To avoid requiring BF-CBC > for this, special this one usage of BF-CBC enough to avoid a hard > requirement on Blowfish in the default configuration. > > Signed-off-by: Arne Schwabe <a...@rfc2549.org> > > Patch v2: add more clarifying comment, do not warn about OCC only insecure > ciphers, code improvements > > Patch V3: Put ciphername resolution via ciper_kt_name in the right branch
This still fails one of my test cases - but only one (v2 failed two).
The test case is "udp / p2mp tun, 2.4 server with --ncp-disable" (on
the server).
The client is called as
... --dev tun --proto udp --data-ciphers AES-256-GCM:AES-128-GCM:BF-CBC
(no --cipher setting) and logS
2021-02-16 20:04:51 --cipher is not set. Previous OpenVPN version defaulted to
BF-CBC as fallback when cipher negotiation failed in this case. If you need
this fallback please add '--data-ciphers-fallback BF-CBC' to your configuration
and/or add BF-CBC to --data-ciphers.
...
2021-02-16 20:04:53 PUSH: Received control message: 'PUSH_REPLY,route
10.194.0.0255.255.0.0,route-ipv6 fd00:abcd:194::/48,tun-ipv6,route
10.194.103.1,topology net30,ping 10,ping-restart 30,ifconfig-ipv6
fd00:abcd:194:103::1000/64 fd00:abcd:194:103::1,ifconfig 10.194.103.6
10.194.103.5,peer-id 0'
2021-02-16 20:04:53 Using peer cipher 'BF-CBC'
but something seems to get confused about things:
2021-02-16 20:04:53 Initialization Sequence Completed
2021-02-16 20:05:03 Bad LZO decompression header byte: 166
The server agrees on BF-CBC (same log, different time zone):
Feb 16 14:04:51 phillip tun-udp-p2mp-2.4-noncp[29923]: 2001:608:0:814::f000:11
peer info: IV_CIPHERS=AES-256-GCM:AES-128-GCM:BF-CBC
Feb 16 14:04:51 phillip tun-udp-p2mp-2.4-noncp[29923]: 2001:608:0:814::f000:11
Outgoing Data Channel: Cipher 'BF-CBC' initialized with 128 bit key
Feb 16 14:04:51 phillip tun-udp-p2mp-2.4-noncp[29923]: 2001:608:0:814::f000:11
Incoming Data Channel: Cipher 'BF-CBC' initialized with 128 bit key
but packets fail decryption:
Feb 16 14:04:53 phillip tun-udp-p2mp-2.4-noncp[29923]:
cron2-gentoo.ov-amd64/2001:608:0:814::f000:11 Authenticate/Decrypt packet
error: packet HMAC authentication failed
Feb 16 14:05:06 phillip syslogd: last message repeated 103 times
Noticeable fact in the client log: there is no "Data Channel: Cipher..."
line on the client, so maybe this is triggering a new corner case?
Notice 2: there is a test case talking to a 2.3 server *which succeeds*,
but that one has "--cipher BF-CBC". So what fails seems to be "cipher
initialization for 'implicit BF-CBC'".
gert
--
"If was one thing all people took for granted, was conviction that if you
feed honest figures into a computer, honest figures come out. Never doubted
it myself till I met a computer with a sense of humor."
Robert A. Heinlein, The Moon is a Harsh Mistress
Gert Doering - Munich, Germany g...@greenie.muc.de
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