Slashdot Mirror
There Are Real Reasons For Linux To Replace ifconfig, netstat and Other Classic Tools (utoronto.ca)
Several readers have shared a blog post: One of the ongoing system administration controversies in Linux is that there is an ongoing effort to obsolete the old, cross-Unix standard network administration and diagnosis commands of ifconfig, netstat and the like and replace them with fresh new Linux specific things like ss and the ip suite. Old sysadmins are generally grumpy about this; they consider it yet another sign of Linux's 'not invented here' attitude that sees Linux breaking from well-established Unix norms to go its own way. Although I'm an old sysadmin myself, I don't have this reaction. Instead, I think that it might be both sensible and honest for Linux to go off in this direction. There are two reasons for this, one ostensible and one subtle.
The ostensible surface issue is that the current code for netstat, ifconfig, and so on operates in an inefficient way. Per various people, netstat et al operate by reading various files in /proc, and doing this is not the most efficient thing in the world (either on the kernel side or on netstat's side). You won't notice this on a small system, but apparently there are real impacts on large ones. Modern commands like ss and ip use Linux's netlink sockets, which are much more efficient. In theory netstat, ifconfig, and company could be rewritten to use netlink too; in practice this doesn't seem to have happened and there may be political issues involving different groups of developers with different opinions on which way to go.
(Netstat and ifconfig are part of net-tools, while ss and ip are part of iproute2.)
However, the deeper issue is the interface that netstat, ifconfig, and company present to users. In practice, these commands are caught between two masters. On the one hand, the information the tools present and the questions they let us ask are deeply intertwined with how the kernel itself does networking, and in general the tools are very much supposed to report the kernel's reality. On the other hand, the users expect netstat, ifconfig and so on to have their traditional interface (in terms of output, command line arguments, and so on); any number of scripts and tools fish things out of ifconfig output, for example. As the Linux kernel has changed how it does networking, this has presented things like ifconfig with a deep conflict; their traditional output is no longer necessarily an accurate representation of reality.
The ostensible surface issue is that the current code for netstat, ifconfig, and so on operates in an inefficient way. Per various people, netstat et al operate by reading various files in /proc, and doing this is not the most efficient thing in the world (either on the kernel side or on netstat's side). You won't notice this on a small system, but apparently there are real impacts on large ones. Modern commands like ss and ip use Linux's netlink sockets, which are much more efficient. In theory netstat, ifconfig, and company could be rewritten to use netlink too; in practice this doesn't seem to have happened and there may be political issues involving different groups of developers with different opinions on which way to go.
(Netstat and ifconfig are part of net-tools, while ss and ip are part of iproute2.)
However, the deeper issue is the interface that netstat, ifconfig, and company present to users. In practice, these commands are caught between two masters. On the one hand, the information the tools present and the questions they let us ask are deeply intertwined with how the kernel itself does networking, and in general the tools are very much supposed to report the kernel's reality. On the other hand, the users expect netstat, ifconfig and so on to have their traditional interface (in terms of output, command line arguments, and so on); any number of scripts and tools fish things out of ifconfig output, for example. As the Linux kernel has changed how it does networking, this has presented things like ifconfig with a deep conflict; their traditional output is no longer necessarily an accurate representation of reality.
keep the command names the same but rewrite how they function? Nah makes too much fucking sense. I've had distros where my default route wasn't working and traceroute wasn't even installed by default. Talk about a shit show. What was the reason for replacing "route" anyhow? It's worked for decades and done one thing.
Only the State obtains its revenue by coercion. - Murray Rothbard
Unix was founded on the ideas of lots os simple command line tools that do one job well and don't depend on system idiosyncracies. If you make the tool have to know the lower layers of the system to exploit them then you break the encapsulation. Polling proc has worked across eons of linux flavors without breaking. when you make everthing integrated it creates paralysis to change down the road for backward compatibility. small speed game now for massive fragility and no portability later.
Some drink at the fountain of knowledge. Others just gargle.
What moron has called the tool SS ? I thing someone who does not check Google first. It is not only Unix history being wiped here.
A LOT of scripts use ifconfig and friends. Changing them would be bad, imho. Better would be to call it ifconfig6 or whatever if you're going to change the output or the meaning of commands, so you don't break existing scripts.
In general, it's better for application programs, including scripts to use an application programming interface (API) such as /proc, rather than a user interface such as ifconfig, but in reality tons of scripts do use ifconfig and such.
I'm responsible a lot of production systems (somewhere around a thousand VMs, it varies), so of course I worry about CPU use, memory use, I/O, etc. I have never, ever, in decades of sysadmin'ing, worried about how much of the above ifconfig or netstat take. (It's not like what's in /proc are actual files, after all; /proc a kernel interface.)
Worried about efficiency? In the aggregate you'll waste more CPU- and man-hours compiling and debugging your replacement tools than using ifconfig or netstat will. Go spend that time on something useful.
-- Alastair
Linux has one of the few IP stacks that isn't derived from the BSD stack, which in the industry is considered the reference design. Instead for linux, a new stack with it's own bugs and peculiarities was cobbled up.
Reference designs are a good thing to promote interoperability. As far as TCP/IP is concerned, linux is the biggest and ugliest stepchild. A theme that fits well into this whole discussion topic, actually.