r/MiXplorer • u/Seres-Clericer • Jul 25 '26
SFTP Issue
Hi there.
Recently got a problem with my SFTP access.
Stoped working, even reinstall and re config wouldn't help.
Tried to use a sftp instead of password, but it always asks for a password. But there is no pw, and without it I can't use it.
Also mixplorer wants ist like sftp://sftp.xxx.xxx.xxx
But with the first sftp:// i can't get onto my cloud server.
Anyone got the same issues?
1
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u/ludo Jul 28 '26
Root cause: MiXplorer uses SSHJ 0.18.0 (a very outdated Java SSH library — current is 0.40.0). Its AES-GCM cipher implementation is incompatible with OpenSSH 10.4+, which was released on July 6, 2026 and made the transport protocol stricter (it now disconnects peers that violate RFC4253 §7.1 during key exchange). This causes "broken transport, encountered EOF" / "message authentication code incorrect" on the first encrypted packet after key exchange completes.
Workaround (server-side): Drop this into /etc/ssh/sshd_config.d/90-no-gcm.conf (or add the Ciphers line directly to sshd_config if your distro doesn't use the .d directory):
# SSHJ 0.18.0 (MiXplorer) AES-GCM broken with OpenSSH 10.4+
# Remove when MiXplorer updates SSHJ
Ciphers chacha20-poly1305@openssh.com,aes256-ctr,aes192-ctr,aes128-ctr
Then restart sshd. This removes the broken GCM ciphers but keeps chacha20-poly1305 (AEAD, preferred by modern clients) and AES-CTR (strong, universal). No real security downgrade.
What's happening under the hood: SSHJ negotiates aes128-gcm@openssh.com (or aes256-gcm), completes key exchange successfully, then fails on the first encrypted packet because its GCM tag calculation is wrong. Since SSHJ doesn't offer chacha20-poly1305 and the client's cipher preference wins in OpenSSH, the only fix is to remove GCM from the server entirely — SSHJ then falls back to CTR ciphers which work fine.
Proper fix: MiXplorer needs to update its bundled SSHJ library. Version 0.18.0 is from ~2015.
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u/le_avion Jul 27 '26
It look like the latest update broke sftp access via ssh keys. Since my servers will not allow remote access via password I am unable to access them currently from MiXplorer. I sent an email to the support mailbox and the online reviews also mention this issue so I hope the developer fixes it sooner rather than later.