--rc; Listening on IPv4+v6 Socket instead only IPv4

benba · September 30, 2021, 11:52am

What is the problem you are having with rclone?

I expect that rclone listen only on an IPv4 Socket.

What is your rclone version (output from `rclone version`)

rclone v1.56.0-DEV

os/version: unknown
os/kernel: 3.10.108 (x86_64)
os/type: linux
os/arch: amd64
go/version: go1.17
go/linking: static
go/tags: none

Which OS you are using and how many bits (eg Windows 7, 64 bit)

DSM 7, Linux, Kernel 3.10.108, 64-bit

Which cloud storage system are you using? (eg Google Drive)

Google Drive, but doesn't matter

The command you were trying to run (eg `rclone copy /tmp remote:tmp`)

rclone copy GoogleDrive: /local --rc --rc-addr 0.0.0.0:5572

sudo netstat -nl | grep :5572
Password: 
tcp6       0      0 :::5572                 :::*                    LISTEN

albertony · September 30, 2021, 12:10pm

Yes, it listens on both IPv4 and IPv6. This one is related, I think its the same library (httplib) that handles rc:

Animosity022 · September 30, 2021, 12:18pm

It's really a non issue as new kernels have IPV6 enabled. It listens on both and if you have only IPV4 traffic, it will communicate via that.

Are you seeing any issues?

sweh · September 30, 2021, 1:28pm

It could potentially be an issue 'cos IPv4 and IPv6 have different firewalls, routing rules, etc. Someone who is dual stacked may find it's exposing a port to the internet on IPv6 that shouldn't be.

Also it breaks the principle of least surprise; if the user says 0.0.0.0 then they specifically are asking for IP4. :::12345 would be both stacks.

Animosity022 · September 30, 2021, 1:31pm

Sure but if I really didn't want IPV6, I would disable on the server (which is what I do since Verizon FIOS doesn't support IPV6).

Do you think someone mixes IPV4 and IPV6 on the same server with separate rules/routing (not being sarcastic as I don't have any IPV6) and am curious if folks do that or not?

sweh · September 30, 2021, 1:49pm

My home network (also FIOS) is dual stacked with a HEnet tunnel to provide the IPv6 connectivity. This means my home servers are reachable directly from the internet over IPv6 but not on IPv4 ('cos of NAT requirements). iptables and ip6tables are managed independently on Linux. Building a home router · Ramblings of a Unix Geek

My colo VMs also are dual stacked ('cos the providers support that) so those different iptable rules are important.

I also have IPv4 tunnels between various servers.

(I know; I'm not normal :-))

When I ask for an IPv4 address I expect an IPv4 address, not an IPv6 address.

(This bug doesn't impact me 'cos I don't use rclone as a server, but I do consider it a bug).

Animosity022 · September 30, 2021, 1:51pm

I would never accuse you of being normal

Yep, it definitely is a bug.

ncw · October 1, 2021, 2:28pm

This behaviour comes from the Go standard library which rclone uses...

I made an issue here

github.com/golang/go

net: Listen("tcp", "0.0.0.0:1234") binds to IPv6 addresses

opened 02:28PM - 01 Oct 21 UTC

ncw

### What version of Go are you using (`go version`)? <pre> go version go1.17.1 linux/amd64 </pre> ### Does this issue reproduce with the latest release? Yes ### What operating system and processor architecture are you using (`go env`)? <details><summary><code>go env</code> Output</summary><br><pre> GO111MODULE="" GOARCH="amd64" GOBIN="" GOCACHE="/home/ncw/.cache/go-build" GOENV="/home/ncw/.config/go/env" GOEXE="" GOEXPERIMENT="" GOFLAGS="" GOHOSTARCH="amd64" GOHOSTOS="linux" GOINSECURE="" GOMODCACHE="/home/ncw/go/pkg/mod" GONOPROXY="" GONOSUMDB="" GOOS="linux" GOPATH="/home/ncw/go" GOPRIVATE="" GOPROXY="https://proxy.golang.org,direct" GOROOT="/opt/go/go1.17" GOSUMDB="sum.golang.org" GOTMPDIR="" GOTOOLDIR="/opt/go/go1.17/pkg/tool/linux_amd64" GOVCS="" GOVERSION="go1.17.1" GCCGO="/usr/bin/gccgo" AR="ar" CC="gcc" CXX="g++" CGO_ENABLED="1" GOMOD="/dev/null" CGO_CFLAGS="-g -O2" CGO_CPPFLAGS="" CGO_CXXFLAGS="-g -O2" CGO_FFLAGS="-g -O2" CGO_LDFLAGS="-g -O2" PKG_CONFIG="pkg-config" GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build3014442064=/tmp/go-build -gno-record-gcc-switches" </pre></details> ### What did you do? Run this program ```go package main import ( "fmt" "log" "net" "os" "os/exec" "strings" ) func main() { if len(os.Args) != 2 { log.Fatalf("Syntax: %s bind_address", os.Args[0]) } bindAddr := os.Args[1] go func() { _, err := net.Listen("tcp", bindAddr) if err != nil { log.Fatalf("net.Listen failed: %v", err) } }() // Read netstat cmd := exec.Command("netstat", "-tuanp") out, err := cmd.Output() if err != nil { log.Fatal(err) } // Print netstat lines with our PID in pid := fmt.Sprint(os.Getpid()) for _, line := range strings.Split(string(out), "\n") { if strings.Contains(line, pid) { fmt.Println(line) } } } ``` I get this ``` $ ./listen-bug 127.0.0.1:1234 tcp 0 0 127.0.0.1:1234 0.0.0.0:* LISTEN 3179765/./listen-bu $ ./listen-bug 0.0.0.0:1234 tcp6 0 0 :::1234 :::* LISTEN 3179773/./listen-bu ``` Note the second of these is listening on IPv6 even though we explictly gave it an IPv4 bind address. ### What did you expect to see? I expected to see it not binding to IPv6 addresses, something like this ``` $ ./listen-bug 0.0.0.0:1234 tcp 0 0 0.0.0.0:1234 0.0.0.0:* LISTEN 3179765/./listen-bu ``` ### What did you see instead? I see it binding to IPv4 and IPv6 addresses ``` $ ./listen-bug 0.0.0.0:1234 tcp6 0 0 :::1234 :::* LISTEN 3179773/./listen-bu ``` This was originally discussed in the [rclone forum](https://forum.rclone.org/t/rc-listening-on-ipv4-v6-socket-instead-only-ipv4/26768)

system · October 4, 2021, 2:28pm

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