Definition of interfaces in ifconfig

Matthew Seaman m.seaman at
Sat Aug 16 14:52:57 PDT 2003

On Sat, Aug 16, 2003 at 03:58:17PM -0500, Charles Howse wrote:
> Hi,
> When I do:
> # ifconfig
> I see the following interfaces listed:
> 	inet netmask 0xffffff00 broadcast
> 	inet6 fe80::2e0:29ff:fe11:ff8a%tx0 prefixlen 64 scopeid 0x1 
> 	ether 00:e0:29:11:ff:8a
> 	media: Ethernet autoselect (100baseTX <full-duplex>)
> 	status: active
> lp0: flags=8810<POINTOPOINT,SIMPLEX,MULTICAST> mtu 1500
> sl0: flags=c010<POINTOPOINT,LINK2,MULTICAST> mtu 552
> faith0: flags=8002<BROADCAST,MULTICAST> mtu 1500
> lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 16384
> 	inet6 ::1 prefixlen 128 
> 	inet6 fe80::1%lo0 prefixlen 64 scopeid 0x5 
> 	inet netmask 0xff000000 
> ppp0: flags=8010<POINTOPOINT,MULTICAST> mtu 1500
> I entered sysinstall/configure/network/network devices and found out
> what they all are.
> The faith0 device was listed as unknown.
> I know tx0 is my one and only nic, we can keep it.
> lp0 is the parallel port, don't need it, don't plan to do any printing
> from this machine.
> lo0 is the loopback interface, that's cool.
> I know I don't need a PPP or SLIP interface, I have a LAN connection to
> the Internet, no modem.
> I was able to do:
> # ifconfig faith0 destroy
> And eliminate the faith0 <unknown> device.
> When I try that with sl0 and ppp0 I get an error: ifconfig:
> SIOCIFDESTROY: Invalid Argument.
> I realize that tx0 and lo0 are the only ones that are UP...are the
> others occupying space in memory?
> Can I get rid of some of these guys?  How?

You can get rid of the superfluous interfaces by building yourself a
custom kernel with the drivers for those devices commented out.  Be
sure and check the man pages (eg sl(4), ppp(4), faith(4)) and in LINT
(4.x) or NOTES (5.x) to verify you aren't chopping out something
useful.  Nb. the ppp0 interface can only be generated by the kernel
pppd(8). The userland ppp(8) which is completely independent of the
kernel mode ppp uses tun0... interfaces that are dynamically generated
as required -- this daemon is what most people use for dial-up




Dr Matthew J Seaman MA, D.Phil.                       26 The Paddocks
                                                      Savill Way
PGP:         Marlow
Tel: +44 1628 476614                                  Bucks., SL7 1TH UK
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