I try to sshfs mount a remote dir, but the mounted files are not writable. I have run out of ideas or ways to debug this. Is there anything I should check on the remote server?I am on an Xubuntu 14.04. I mount remote dir of a 14.04 Ubuntu.local $ lsb_release -aNo LSB modules are available.Distributor ID: UbuntuDescription:    Ubuntu 14.04.3 LTSRelease:    14.04Codename:   trustyI changed the /etc/fuse.conflocal $ sudo cat /etc/fuse.conf# /etc/fuse.conf - Configuration file for Filesystem in Userspace (FUSE)# Set the maximum number of FUSE mounts allowed to non-root users.# The default is 1000.#mount_max = 1000# Allow non-root users to specify the allow_other or allow_root mount options.user_allow_otherAnd my user is in the fuse grouplocal $ sudo grep fuse /etc/groupfuse:x:105:MY_LOACL_USERNAMEAnd I mount the remote dir with (tried with/without combinations of sudo, default_permissions, allow_other):local $sudo sshfs -o allow_other,default_permissions -o IdentityFile=/path/to/ssh_key  REMOTE_USERNAME@REMOTE_HOST:/remote/dir/path/  /mnt/LOCAL_DIR_NAME/The REMOTE_USERNAME has write permissions to the dir/files (on the remote server).I tried the above command without sudo, default_permissions, and in all cases I get:local $ ls -al /mnt/LOCAL_DIR_NAME/a_file-rw-rw-r-- 1 699 699 1513 Aug 12 16:08 /mnt/LOCAL_DIR_NAME/a_filelocal $ test -w /mnt/LOCAL_DIR_NAME/a_file && echo Writable || echo Not WritableNot WritableClarification 0In response to user3188445's comment:$ whoamiLOCAL_USER$ cd$ mkdir test_mnt$ sshfs -o allow_other,default_permissions -o IdentityFile=/path/to/ssh_key  REMOTE_USERNAME@REMOTE_HOST:/remote/dir/path/ test_mnt/$ ls test_mnt/I see the contents of the dir correctly$ ls -al test_mnt/total 216drwxr-xr-x  1 699 699  4096 Aug 12 16:42 .drwxr----- 58 LOCAL_USER LOCAL_USER  4096 Aug 17 15:46 ..-rw-r--r--  1 699 699  2557 Jul 30 16:48 sample_filedrwxr-xr-x  1 699 699  4096 Aug 11 17:25 sample_dir$ touch test_mnt/new_file touch: cannot touch test_mnt/new_file: Permission denied# extra info: SSH to the remote host and check file permissions$ ssh REMOTE_USERNAME@REMOTE_HOST# on remote host$ ls -al /remote/dir/path/lrwxrwxrwx 1 root root 18 Jul 30 13:48 /remote/dir/path/ -> /srv/path/path/path/$ cd /remote/dir/path/$ ls -altotal 216drwxr-xr-x 26 REMOTE_USERNAME  REMOTE_USERNAME   4096 Aug 12 13:42 .drwxr-xr-x  4 root root  4096 Jul 30 14:37 ..-rw-r--r--  1 REMOTE_USERNAME  REMOTE_USERNAME   2557 Jul 30 13:48 sample_filedrwxr-xr-x  2 REMOTE_USERNAME  REMOTE_USERNAME   4096 Aug 11 14:25 sample_dir
Mount with sshfs and write file permissions
linux;fuse;sshfs
The question was answered in a linux mailing list; I post a translated answer here for completeness.SolutionThe solution is not to used both the options default_permissions and allow_other (which I didn't try in my original experiments).ExplanationThe problem seems to be quite simple. When you give the option default_permissions in fusermount then fuse's permission control of the fuse mount is handled by the kernel and not by fuse. This means that the REMOTE_USER's uid/gid aren't mapped to the LOCAL_USER (sshfs.c IDMAP_NONE). It works the same way as a simple nfs fs without mapping. So, it makes sense to prohibit the access, if the uid/gid numbers don't match.If you have the option allow_other then this dir is writable only by the local user with uid 699, if it exists.From fuse's man:'default_permissions'   By default FUSE doesn't check file access permissions, the   filesystem is free to implement its access policy or leave it to   the underlying file access mechanism (e.g. in case of network   filesystems).  This option enables permission checking, restricting   access based on file mode.  It is usually useful together with the   'allow_other' mount option.'allow_other'   This option overrides the security measure restricting file access   to the user mounting the filesystem.  This option is by default only   allowed to root, but this restriction can be removed with a   (userspace) configuration option.