I hope this isn't off-topic by too much. If it is, a word to me privately and I'll wait for responses to queries I've made elsewhere.
I maintain two FTP servers and support four Windows-based FTP clients for users of those servers--FTP Voyager, FlashFXP, Filezilla, and WinSCP. One server accepts all four clients, the other accepts all but FTP Voyager, indicating a configuration difference. I've asked about this on the comp.security.ssh Usenet newsgroup, but Usenet being what it is, I might have to wait at least a week before getting a response of any kind, and my Voyager users are starting to get restless for an answer as to what I did to break access for them--i.e., they'd rather fight than switch. Here are the two sshd_configs without comments, greatly shortening what you'll be looking at. First, the one that accepts all four clients: SyslogFacility AUTHPRIV PermitRootLogin without-password AuthorizedKeysFile .ssh/authorized_keys PermitEmptyPasswords no PasswordAuthentication yes ChallengeResponseAuthentication no GSSAPIAuthentication yes GSSAPICleanupCredentials yes UsePAM yes X11Forwarding yes Compression delayed Banner /etc/issue.net AcceptEnv LANG LC_CTYPE LC_NUMERIC LC_TIME LC_COLLATE LC_MONETARY LC_MESSAGES AcceptEnv LC_PAPER LC_NAME LC_ADDRESS LC_TELEPHONE LC_MEASUREMENT AcceptEnv LC_IDENTIFICATION LC_ALL LANGUAGE AcceptEnv XMODIFIERS Subsystem sftp internal-sftp ListenAddress :: ListenAddress 0.0.0.0 Now, the one from the server that won't accept SFTP-over-ssh connections from FTP Voyager: Protocol 2 HostKey /etc/ssh/ssh_host_rsa_key HostKey /etc/ssh/ssh_host_dsa_key HostKey /etc/ssh/ssh_host_ecdsa_key HostKey /etc/ssh/ssh_host_ed25519_key UsePrivilegeSeparation yes KeyRegenerationInterval 3600 ServerKeyBits 1024 SyslogFacility AUTH LogLevel INFO LoginGraceTime 120 PermitRootLogin without-password StrictModes yes RSAAuthentication yes PubkeyAuthentication yes IgnoreRhosts yes RhostsRSAAuthentication no HostbasedAuthentication no PermitEmptyPasswords no ChallengeResponseAuthentication no X11Forwarding yes X11DisplayOffset 10 PrintMotd no PrintLastLog yes TCPKeepAlive yes AcceptEnv LANG LC_* Subsystem sftp internal-sftp UsePAM yes Match Group documenters ChrootDirectory /home/documenters AllowTCPForwarding no X11Forwarding no ForceCommand internal-sftp At first, I thought the problem has to do with the stanza beginning with the MatchGroup directive, so I commented it out. The problem didn't go away, and I don't perceive any differences between the two configurations except maybe a few options that are defined explicitly which are already at their default values according to the ssh documentation. Any help greatly appreciated, on- or off-list.