Opened 4 years ago

Last modified 3 years ago

#10712 new Bug report

filezilla client not falling back to IPv4

Reported by: hjadsfadfasdf Owned by:
Priority: normal Component: FileZilla Client
Keywords: ipv6 Cc:
Component version: 3.12.0.2 Operating system type: Linux
Operating system version: Ubuntu 15.10

Description

sftp connection, host has both IPv4 and IPv6. When service on IPv6 is not reachable, filezilla does not attempt to connect via IPv4.

Change History (3)

comment:1 Changed 4 years ago by Tim Kosse

Status: newmoreinfo

Have you tried a bigger timeout value yet? If the server is firewalled, the connection will time out, whereas a non-firewalled server would properly reject the connection.

comment:2 Changed 4 years ago by hjadsfadfasdf

Status: moreinfonew

In this case the IPv6 address was no longer in use.

According to rfc4443 Section 3.1 there should be a Destination Unreachable Message with code 3 (A OpenVZ node statically routed a /64 prefix to the container, but the guest OS is not configured with that specific address, say the packet was destinated to 2001:DB8:1:2::2/64 but the guest is configured with 2001:DB8:1:2::1/64).

But for whatever reason no ICMPv6 error message was received (quite common for broken IPv6 implementation, plenty of people still thinks dropping ICMP means security....). I do not know if the host or the network is dropping ICMPv6.

And in this case FileZilla does not even attempt to connect via IPv4.

Last edited 4 years ago by hjadsfadfasdf (previous) (diff)

comment:3 Changed 3 years ago by Kevin Gut

I have the same issue with IPv4 fallback on Windows Server 2008 R2.

Problem in my case is not the destination, but the source. My ISP (where the client is used) has no support for IPv6 so there will also never be a proper ICMP response. I have tried manually disabling IPv6 protocol on the network adapter, but FileZilla still insists on using IPv6. The log shows no trace messages of the socket ever attempting to connect, also the second attempt is done using the same (failed) IP address.

Log output:

Status:	Verbindung zum Server getrennt
Trace:	CControlSocket::DoClose(64)
Trace:	CControlSocket::DoClose(64)
Trace:	CControlSocket::DoClose(64)
Trace:	CFileZillaEnginePrivate::ResetOperation(0)
Status:	Auflösen der IP-Adresse für bitmessage.ch
Status:	Verbinde mit [2002:92e4:70fc::92e4:70fc]:21...
Fehler:	Zeitüberschreitung der Verbindung nach 20 Sekunden Inaktivität
Trace:	CControlSocket::DoClose(2050)
Trace:	CFtpControlSocket::ResetOperation(2114)
Trace:	CControlSocket::ResetOperation(2114)
Fehler:	Herstellen der Verbindung zum Server fehlgeschlagen
Trace:	CFileZillaEnginePrivate::ResetOperation(2114)
Status:	Nächsten Versuch abwarten...
Trace:	CControlSocket::DoClose(64)
Trace:	CControlSocket::DoClose(64)
Status:	Auflösen der IP-Adresse für bitmessage.ch
Status:	Verbinde mit [2002:92e4:70fc::92e4:70fc]:21...
Fehler:	Zeitüberschreitung der Verbindung nach 20 Sekunden Inaktivität
Trace:	CControlSocket::DoClose(2050)
Trace:	CFtpControlSocket::ResetOperation(2114)
Trace:	CControlSocket::ResetOperation(2114)
Fehler:	Herstellen der Verbindung zum Server fehlgeschlagen
Trace:	CFileZillaEnginePrivate::ResetOperation(2114)
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