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If SCP works but SFTP doesn't, then they are most likely running an outdated version of OpenSSH with insecure algorithms.
by encryptluks2 5y ago
If SCP works but SFTP doesn't, then they are most likely running an outdated version of OpenSSH with insecure algorithms.
- hackerbrother 5y agoOpenSSH's habit of giving their tools the same name as protocols makes this confusing to talk about. SCP (the tool) uses SFTP (the protocol) by default, right?
- formerly_proven 5y agoscp uses a custom stream protocol over stdout/stdin. It's more like a tarpipe, though shares nothing in terms of format with that. SFTP is essentially RPC for the various I/O syscalls (open, read, write, ...) - it's basically NFS-as-a-user over SSH. Read/write size is limited to 32 kB per request (in OpenSSH / minimum supported size).
- acdha 5y agoscp the tool uses the SCP protocol by default. Recent versions allow you to use sftp instead: -s Use the SFTP protocol for transfers rather than the original scp protocol.
- hackerbrother 5y agoAh, now I know why I was confused. It hasn't happened yet, but sftp will be the default protocol soon. > A near-future release of OpenSSH will switch scp(1) from using the legacy scp/rcp protocol to using SFTP by default. https://www.openssh.com/releasenotes.html https://www.openssh.com/releasenotes.html
- adrian_b 5y agoNo, many administrators, like myself, disable the SFTP protocol, even if they always use the up-to-date OpenSSH. I also always remove scp because I use only rsync over ssh, which does not have the inherent bugs of scp and sftp and is also much faster.