Closed mmokrejs closed 1 year ago
schwabe
commented
1 year ago You are running the client without client or pull ie in p2p mode. Either you run both sides in p2p mode or you one side with --server and the other side with --pull/--client. Trying to use p2p mode one side and --server on the other will just break.
mmokrejs
commented
1 year ago Differences in openvpn --show-ciphers outputs:
$ diff -u -w /tmp/myserver.ciphers.txt /tmp/client2.ciphers.txt
--- /tmp/myserver.ciphers.txt 2023-07-17 15:31:00.268477628 +0200
+++ /tmp/client2.ciphers.txt 2023-07-17 15:31:28.668477493 +0200
@@ -9,16 +9,19 @@
AES-128-CFB (128 bit key, 128 bit block, TLS client/server mode only)
AES-128-CFB1 (128 bit key, 128 bit block, TLS client/server mode only)
AES-128-CFB8 (128 bit key, 128 bit block, TLS client/server mode only)
+AES-128-GCM (128 bit key, 128 bit block, TLS client/server mode only)
AES-128-OFB (128 bit key, 128 bit block, TLS client/server mode only)
AES-192-CBC (192 bit key, 128 bit block)
AES-192-CFB (192 bit key, 128 bit block, TLS client/server mode only)
AES-192-CFB1 (192 bit key, 128 bit block, TLS client/server mode only)
AES-192-CFB8 (192 bit key, 128 bit block, TLS client/server mode only)
+AES-192-GCM (192 bit key, 128 bit block, TLS client/server mode only)
AES-192-OFB (192 bit key, 128 bit block, TLS client/server mode only)
AES-256-CBC (256 bit key, 128 bit block)
AES-256-CFB (256 bit key, 128 bit block, TLS client/server mode only)
AES-256-CFB1 (256 bit key, 128 bit block, TLS client/server mode only)
AES-256-CFB8 (256 bit key, 128 bit block, TLS client/server mode only)
+AES-256-GCM (256 bit key, 128 bit block, TLS client/server mode only)
AES-256-OFB (256 bit key, 128 bit block, TLS client/server mode only)
ARIA-128-CBC (128 bit key, 128 bit block)
ARIA-128-CFB (128 bit key, 128 bit block, TLS client/server mode only)
@@ -54,29 +57,14 @@
CAMELLIA-256-CFB8 (256 bit key, 128 bit block, TLS client/server mode only)
CAMELLIA-256-OFB (256 bit key, 128 bit block, TLS client/server mode only)
CHACHA20-POLY1305 (256 bit key, stream cipher, TLS client/server mode only)
-SEED-CBC (128 bit key, 128 bit block)
-SEED-CFB (128 bit key, 128 bit block, TLS client/server mode only)
-SEED-OFB (128 bit key, 128 bit block, TLS client/server mode only)
SM4-CBC (128 bit key, 128 bit block)
SM4-CFB (128 bit key, 128 bit block, TLS client/server mode only)
+SM4-GCM (128 bit key, 128 bit block, TLS client/server mode only)
SM4-OFB (128 bit key, 128 bit block, TLS client/server mode only)
-AES-128-GCM (128 bit key, 128 bit block, TLS client/server mode only)
-AES-192-GCM (192 bit key, 128 bit block, TLS client/server mode only)
-AES-256-GCM (256 bit key, 128 bit block, TLS client/server mode only)
The following ciphers have a block size of less than 128 bits,
and are therefore deprecated. Do not use unless you have to.
-BF-CBC (128 bit key, 64 bit block)
-BF-CFB (128 bit key, 64 bit block, TLS client/server mode only)
-BF-OFB (128 bit key, 64 bit block, TLS client/server mode only)
-CAST5-CBC (128 bit key, 64 bit block)
-CAST5-CFB (128 bit key, 64 bit block, TLS client/server mode only)
-CAST5-OFB (128 bit key, 64 bit block, TLS client/server mode only)
-DES-CBC (64 bit key, 64 bit block)
-DES-CFB (64 bit key, 64 bit block, TLS client/server mode only)
-DES-CFB1 (64 bit key, 64 bit block, TLS client/server mode only)
-DES-CFB8 (64 bit key, 64 bit block, TLS client/server mode only)
DES-EDE-CBC (128 bit key, 64 bit block)
DES-EDE-CFB (128 bit key, 64 bit block, TLS client/server mode only)
DES-EDE-OFB (128 bit key, 64 bit block, TLS client/server mode only)
@@ -85,17 +73,4 @@
DES-EDE3-CFB1 (192 bit key, 64 bit block, TLS client/server mode only)
DES-EDE3-CFB8 (192 bit key, 64 bit block, TLS client/server mode only)
DES-EDE3-OFB (192 bit key, 64 bit block, TLS client/server mode only)
-DES-OFB (64 bit key, 64 bit block, TLS client/server mode only)
-DESX-CBC (192 bit key, 64 bit block)
-IDEA-CBC (128 bit key, 64 bit block)
-IDEA-CFB (128 bit key, 64 bit block, TLS client/server mode only)
-IDEA-OFB (128 bit key, 64 bit block, TLS client/server mode only)
-RC2-40-CBC (40 bit key, 64 bit block)
-RC2-64-CBC (64 bit key, 64 bit block)
-RC2-CBC (128 bit key, 64 bit block)
-RC2-CFB (128 bit key, 64 bit block, TLS client/server mode only)
-RC2-OFB (128 bit key, 64 bit block, TLS client/server mode only)
-RC5-CBC (128 bit key, 64 bit block)
-RC5-CFB (128 bit key, 64 bit block, TLS client/server mode only)
-RC5-OFB (128 bit key, 64 bit block, TLS client/server mode only)client2 # emerge -pv openvpn openssl
These are the packages that would be merged, in order:
Calculating dependencies... done!
Dependency resolution took 1.72 s.
[ebuild R ] dev-libs/openssl-3.1.1-r1:0/3::gentoo USE="asm -fips -ktls -rfc3779 -sctp -static-libs -test -tls-compression -vanilla -verify-sig -weak-ssl-ciphers" CPU_FLAGS_X86="(sse2)" 0 KiB
[ebuild R ] net-vpn/openvpn-2.6.4::gentoo USE="inotify iproute2 lz4 lzo openssl pam plugins systemd -dco -down-root -examples -mbedtls -pkcs11 (-selinux) -test" 0 KiBmyserver # emerge -pv openvpn openssl
These are the packages that would be merged, in order:
Calculating dependencies... done!
[ebuild R ] dev-libs/openssl-1.1.1u:0/1.1::gentoo USE="asm -rfc3779 -sctp (-sslv3) -static-libs -test -tls-compression -tls-heartbeat -vanilla -verify-sig -weak-ssl-ciphers" CPU_FLAGS_X86="(sse2)" 9,661 KiB
[ebuild R ] net-vpn/openvpn-2.6.4::gentoo USE="examples inotify iproute2 lz4 lzo openssl pam plugins -dco -down-root -mbedtls -pkcs11 (-selinux) -systemd -test" 0 KiB
Total: 2 packages (2 reinstalls), Size of downloads: 9,661 KiB
WARNING: One or more updates/rebuilds have been skipped due to a dependency conflict:
dev-libs/openssl:0
(dev-libs/openssl-3.0.9-r1:0/3::gentoo, ebuild scheduled for merge) USE="asm -fips -ktls -rfc3779 -sctp -static-libs -test -tls-compression -vanilla -verify-sig -weak-ssl-ciphers" CPU_FLAGS_X86="(sse2)" conflicts with
>=dev-libs/openssl-1.0.0:0/1.1= required by (dev-db/mariadb-10.5.16:10.5/18::gentoo, installed) USE="backup cracklib pam perl server userland_GNU xml -bindist -columnstore -debug -extraengine -galera -innodb-lz4 -innodb-lzo -innodb-snappy -jdbc -jemalloc -kerberos -latin1 (-mroonga) -numa -odbc -oqgraph -profiling -rocksdb -s3 (-selinux) -sphinx -sst-mariabackup -sst-rsync -static -systemd -systemtap -tcmalloc -test -yassl"
^^^^^^^
cron2
commented
1 year ago Having a SSL lib without AES-GCM ciphers would be bad indeed - but this is not problem here, the server log shows that the client signals AES-GCM support, and the server is willing to accept it:
Jul 17 14:55:19 myserver openvpn[6673]: client2_ip:53828 peer info: IV_CIPHERS=AES-256-GCM:AES-128-GCM:CHACHA20-POLY1305
Jul 17 14:55:20 myserver openvpn[6673]: client2.mydomain/client2_ip:53828 Data Channel: cipher 'AES-256-GCM', peer-id: 0(maybe there is a bug lurking here, if the server SSL library really has no AES-256-GCM and we do not properly check, but this is not why the client is giving up)
Arne already spotted the real problem:
OpenVPN 2.6.x can auto-negotate ciphers in two modes - peer2peer (which means no client and no server or mode server in the config, just udp-client and udp-server) or real point2multipoint. The second version has a real server, and all clients must have client in their config files.
The Android client can only do client, so it's possible that it can work "as client" if there is no client in the config file - but the linux binary can do all variants, so it needs to be explicitely told what you want it to do.
With 2.5, such configs used to work (by falling back to BF-CBC), but this was more "good luck" than "by design" - and we needed to change this behaviour to get rid of BF-CBC, which is considered insecure today.
mmokrejs
commented
1 year ago I apologize that during all my experiments I commented out the client option from the config file. I was not aware of the P2P mode.
Indeed, the "OpenVPN for Android" app for openvpn 2.x core it included the client option in the generated .ovpn file, I just checked that now.
The openvpn --show-ciphers should be stable-sorted, ideally.
Thank you for your help and detailed explanations.
schwabe
commented
1 year ago --show-ciphers is using the same order as OpenSSL provides. It is not intended for anything than debug purposes.
Provided I got the phone app working with
tls-crypt-v2I find it cumbersome the Linux client fails with:ERROR: failed to negotiate cipher with peer and --data-ciphers-fallback not enabled. No usable data channel cipherHere is a full log from client:
Server logged:
I edited the config files although some of the path are partly visible in the logs above:
2.6.4 client config:
2.6.4 server config: