This bug seems to still be in effect: https://bugzilla.redhat.com/show_bug.cgi?id=919405 https://bugzilla.samba.org/show_bug.cgi?id=9706 (Samba 4.0) I've tested various recent versions of Android apps using jcifs and none can copy a file from a Samba4 file server to the device. Copying from the device to server works fine, as do renames and folder traversal. Apps I tried: ES File Explorer, Ghost Commander (with SMB plugin) and AndSMB. The error on the jcifs side: "Signature verification failed". Versions of Samba I compiled and tested: 4.2.2 and 4.3.0rc1. Samba 3 servers on my network communicate just fine with the apps using jcifs as do all Windows versions I have access to (Windows XP, Vista, 7, 8.1). This may actually be a bug in jcifs. However the Samba 4.0 bug reports suggests it was fixed server-side. I also tried to apply this patch to my 4.3.0rc1 source (source3/smbd/reply.c): https://lists.samba.org/archive/samba-technical/2013-March/090922.html but the source has changed so much between versions 4.0 and 4.3 that I was unable to write comparable code for the 4.3 version.
What does your smb.conf look like ? Have you made smb signing mandatory ?
Created attachment 11413 [details] My current smb.conf
Comment on attachment 11413 [details] My current smb.conf As far as I know, I haven't configured mandatory signing...
So, just trying to get more info. Do the jcifs clients fail with all Samba 4.0.x and above versions, or do they fail with 4.0.x but work with 4.1.x and above ? Can you attach a wireshark trace between client and server showing the failure ? Can you give an *exact* method of reproducing this I can try with an Android phone ?
Closing this, user was using a heavily mangled DC smb.conf and was asked for more info 5 years ago, this has never been supplied.