Connection and login problems

A connection goes through stages: find the host, open a network connection, agree on encryption, then log in. The error tells you which stage failed. Work through the section that matches it.

The host name is not found

linscp could not turn the name into an address.

• Check the spelling in Host name. Enter only the name, such as files.example.org, without sftp:// or a path.
• Test the name on your computer: getent hosts files.example.org. No output means your DNS cannot resolve it either.
• If the host is only reachable on a company network, connect the VPN first.

The connection is refused

The machine answered, but nothing accepts connections on that port.

• Check Port number: 22 for SFTP and SCP, 21 for FTP and explicit FTPS, 990 for implicit FTPS, 443 for HTTPS-based WebDAV and S3.
• The server program may be stopped. Ask the administrator.
• Some servers listen only for one protocol. An SFTP attempt on an FTP-only server is refused, or fails with a message that the server speaks FTP.

The connection times out

Nothing answered at all. Usually a firewall drops the traffic.

• At a cloud provider, open the port in the machine’s firewall or security group for your address.
• On your side, a corporate network may block outgoing SSH or FTP. If you must go through a proxy, set it under Advanced… › Connection › Proxy. See proxies and tunnels.
• For a slow link, raise Server response timeout under Advanced… › Connection.

Other programs connect, linscp does not

Compare carefully: same host, port, user and protocol. If they match, look for something that treats programs differently:

• a desktop firewall or security tool with per-program rules;
• proxy settings that your browser or terminal uses but linscp does not (Options › Preferences › Network, and each site’s Proxy page);
• on Linux with the Flatpak package, the sandbox. Check whether the .deb or AppImage behaves differently.

Login fails

• Wrong user name or password. Both are case-sensitive. Type the password in a text editor first to check the keyboard layout.
• Root login disabled. Many SSH servers refuse root. Log in as an ordinary user.
• Account locked or expired. Only the server’s administrator can tell and fix this. Nobody else can reset your password.
• Key refused. The server does not accept your key for this user. Check that the public key is in that user’s ~/.ssh/authorized_keys, and that ~/.ssh is mode 700 and authorized_keys mode 600 on the server.
• Too many authentication failures. Your SSH agent offers many keys and the server gives up before the right one. Choose the key file under Advanced… › SSH › Authentication and uncheck Attempt authentication using agent.
• Asked for the password again and again. The saved password is wrong, or a master password prompt was cancelled.

See authentication for each method.

SFTP starts, then fails

If login works but SFTP cannot start, the cause is usually on the server:

• The SFTP subsystem is not enabled. Check the Subsystem sftp line in the server’s sshd_config.
• The account’s shell start-up files print text (a greeting, echo lines). That output corrupts the SFTP stream. Print only in interactive shells.

If the server has no SFTP at all, switch the site to SCP.

Host key warnings

A warning that the host key does not match the one stored means either the server was reinstalled or someone is intercepting the connection. Do not accept it until the administrator confirms a new key. See verifying host keys.

TLS certificate errors on Linux

On Linux, linscp does not download intermediate certificates that a server leaves out. A server that sends an incomplete chain is refused, even if browsers or Windows accept it. Ask the operator to send the full chain. If your organisation uses a private CA, add it to the system’s trusted store or point SSL_CERT_FILE at a bundle that includes it. See the security overview.

FTP lists nothing or hangs on transfers

FTP opens a second connection for each listing and transfer. If logging in works but listings time out, toggle Passive mode under Advanced… › Connection. See FTP and FTPS settings.