331
FTP
331 Username OK, Need Password
User name okay, need password. The server recognized the username and is waiting for the corresponding password to complete authentication.
Quand vous voyez ce code
After sending the USER command with a valid username. The server is prompting for the PASS command.
Comment résoudre
Send the PASS command with the correct password. If you get 530 after PASS, the password is wrong — verify your credentials.
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Guides
FTP Reply Codes: Understanding File Transfer Responses
DNS & Networking
TCP Three-Way Handshake and Connection Lifecycle
DNS & Networking
Essential Network Debugging Tools: ping, traceroute, mtr, and tcpdump
DNS & Networking
RFC 959: FTP Protocol Deep Dive
Protocol Deep Dives
TLS 1.3: Faster, Simpler, More Secure
Protocol Deep Dives
Migrating from FTP to SFTP: A Complete Transition Guide
Migration & Upgrades
HTTP Access Log Management: Rotation, Parsing, and Analysis
Production Infrastructure
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FTP Chroot Jail
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rsync
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FTP over TLS (RFC 4217)
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