No More FTP At Debian (debian.org)

New submitter Gary Perkins writes: It looks like anonymous FTP is officially on its way out. While many public repositories have deprecated it in favor of HTTP, I was rather surprised to see Debian completely drop it on their public site. In a blog post, the team cited the FTP's lack of support for caching or acceleration, and declining usage as some of the reasons for their decision.

Comments

Re:Network admins rejoice!

[serviscope_minor]

Or https/http, for simply fetching files.

HTTP is faster to connect

[fred6666]

Every time I used FTP in my sources.list, it was slower to connect. The whole apt-get update process could therefore be twice as long on FTP, compared to HTTP. Even though I guess once connected, the file transfer protocol should be more efficient.

Re:HTTP is faster to connect

[buchner.johannes]

Even though I guess once connected, the file transfer protocol should be more efficient.

There are huge differences between FTP servers in terms of their delivery.
But today's Apache delivers static files extremely fast, by telling the kernel to move a file data onto the network card, so the data are never actually moved to the application. That's fast, and you can still play proxying, cache-freshness and other HTTP tricks on top of this.

Re:HTTP is faster to connect

[Anonymous Coward]

> But today's Apache delivers static files extremely fast, by telling the kernel to move a file data onto the network card, so the data are never actually moved to the application.

Hogwash. Even FreeBSD's accf_http.ko and accf_data.ko modules do not work this way. You cannot bypass "the application" layer -- that's httpd. Possibly you meant moved *by* the application? If so: yes that's true. I'll explain in detail:

I believe what you're trying to speak about is the sendfile(2) syscall. This does not "move file data onto the network card" (that's misleading on your part) -- all it does is allow for the kernel itself to transfer data between two file descriptors, rather than httpd itself doing it. The theory is that this takes less time than the kernel having to copy to userland (httpd), then userland (httpd) doing a read/write, which sends it back up to the kernel, rise lather repeat for every buffer (i.e. it saves a read and write call being done per buffer). Also, FreeBSD's sendfile(2) syscall is zero-copy within kernel space, meaning there are no intermediary buffers used to store copies of the data being transferred (I'm unsure about Linux in this regard).

sendfile(2) has a very precarious history of not working reliably with things like NFS and ZFS, or if working, the performance hit in kernel-land being major. This is why Apache has the EnableSendfile global directive, which defaults to off for a very good reason. The same goes for mmap(2) (EnableMmap, which defaults to on; if you're serving from NFS, you need to disable this for either a specific filesystem path using Location, or disable it globally). sendfile(2) also is known to have other problems, such as incorrect TCP checksum offloading calculation on Linux when using IPv6, and tends to have a transfer limit size of 2GBytes (a signed 32-bit number minus approximately 4096, due to page alignment), even on 64-bit systems (explains why there's sendfile64(2) on Linux). Refer to the Apache 2.4 documentation if you think I'm bluffing. You'll find *IX FTP servers (ex. proftpd) often allow disabling of sendfile as well, for the same reasons. In early 2005 there was there was even a serious security hole in sendfile(2) on FreeBSD 4.x/5.x (see FreeBSD-SA-05:02.sendfile).

It's up to your systems administrator to decide if sendfile(2) is safe for use by whatever program might be using it. In general, it's best to default to not using it unless you know factually the underlying filesystems and applications work reliably with it. I've read a few anecdotal blogs talking about how sendfile(2) on OS X (based on FreeBSD, but these days deviates quite severely) is quite broken as well.

Your other descriptions of use of things like proxying aren't really relevant from a performance perspective (re: "more efficient") -- if anything all this does is waste more resources -- but your point about proper use of HTTP caching directives is relevant as long as the client honours such (ex. ETags, If-Modified-Since, etc.).

Re:HTTP is faster to connect

[dunkelfalke]

FTP convoluted? Seriously? I have recently written an FTP client, it was by far the easiest protocol I have ever implemented. Hell, XMODEM is more complicated.

NEWS FLASH!@!

[faedle]

uucp now deprecated by ftp.

Re:Network admins rejoice!

[Anonymous Coward]

Correct, FTP was never intended to transport files.

Re:Network admins rejoice!

[Anonymous Coward]

While good on paper, what you propose is a lot more complicated. SCP and SFTP are subsystems of SSH, which do not have the degree of fine-grained control and capability as most decent FTP servers do. Rate-limiting is one such example (i.e. rate-limiting only SCP/SFTP but not SSH). Network administrators love to think of the situation simply ("yay, I can remove annoyances relating to TCP port 20 and 21 for FTPs passive and active modes, now just pass TCP port 22 and my job is done!"), but those of us in systems who have to actually try to implement the fine-grained controls for this with SSH/SCP/SFTP are driven absolutely mad because even servers like OpenSSH do not provide that granularity.

In short: SCP/SFTP are no where close to drop-in replacements for FTP.

Farewell FTP

[duke_cheetah2003]

Along with many other antiquated protocols, FTP is now going the way of gopher, telnet and other such early protocols the internet used.

FTP was a neat tool in its day, with lots of anonymous-enabled repositories of free software (and sometimes not-so-free.) Gone are the days of highjacking a server with lots of disk to make it a file dump via FTP.

As more repositories close down, I wonder how they will be replaced? I have not seen much in the way of clearing houses for free software in web-page format, yet. Sure, a lot of linux distros are hosted up on websites, but rarely do you find indexes like you can with FTP easily.

I'll miss the days of using somewhat questionable 'ftp search' websites that tried to scrape as much info as they could from anonymous-enabled FTP servers around the globe.

You'll be missed, good ol' FTP.

Re:Farewell FTP

[eneville]

Sure, a lot of linux distros are hosted up on websites, but rarely do you find indexes like you can with FTP easily.

I'll miss the days of using somewhat questionable 'ftp search' websites that tried to scrape as much info as they could from anonymous-enabled FTP servers around the globe.

You'll be missed, good ol' FTP.

Yes, I think the real problem was just how to embed adverts into the listing output. If that problem could be solved then people would welcome FTP back with open arms.

Re:Debian S released

[A. Craig West]

wget

Re:Debian S released

[omnichad]

How else would you download Firefox without IE/Edge:

In Powershell:
Invoke-WebRequest -OutFile Firefox.exe "https://download.mozilla.org/?product=firefox-53.0-SSL&os=win64&lang=en-US"

But I would rather use Edge than Powershell.