Date: Tue, 9 Feb 2016 22:51:14 +0100 From: Jeremy Boy <jb@jboy.eu> To: freebsd-net@freebsd.org Cc: Jeremy Boy <jb@jboy.eu> Subject: ifconfig with quoted arguments Message-ID: <76A08658-ACD2-426B-865A-45A6A79BBFB4@jboy.eu>
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Hello list, please CC me in replies to this mail, since I am no subscriber to this = list. For safety reasons, we enclose user input to shell commands in quotes. = Until today, the resulting command for ifconfig(8) looked like this: > ifconfig ue0 inet "192.168.2.176 netmask 255.255.255.0" As we figured out, this means that ifconfig sometimes doesn't set the = netmask as we expect it to do: > root@csbuild:~ # ifconfig ue0 > ue0: flags=3D8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu = 1500 > options=3D80001<RXCSUM,LINKSTATE> > ether b8:27:eb:fd:58:69 > inet 192.168.2.176 netmask 0xffff0000 broadcast = 192.168.255.255=20 > media: Ethernet autoselect (100baseTX <full-duplex>) > status: active > nd6 options=3D29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL> > root@csbuild:~ # ifconfig ue0 inet "192.168.2.176 netmask 255.0.0.0" > root@csbuild:~ # echo $? > 0 > root@csbuild:~ # ifconfig ue0 > ue0: flags=3D8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu = 1500 > options=3D80001<RXCSUM,LINKSTATE> > ether b8:27:eb:fd:58:69 > inet 192.168.2.176 netmask 0xffffff00 broadcast 192.168.2.255=20= > media: Ethernet autoselect (100baseTX <full-duplex>) > status: active > nd6 options=3D29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL> > root@csbuild:~ #=20 As you can see, ifconfig sets the netmask to 255.255.255.0, ignoring the = netmask we provided. If provided with a 10.* address, ifconfig sets the = netmask to 255.0.0.0, no matter what actual netmask we entered. Also, it = doesn't exit with a status indicating error, which made it a little = harder to debug this issue. The following works as expected: > root@csbuild:~ # ifconfig ue0 > ue0: flags=3D8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu = 1500 > options=3D80001<RXCSUM,LINKSTATE> > ether b8:27:eb:fd:58:69 > inet 192.168.2.176 netmask 0xffffff00 broadcast 192.168.2.255=20= > media: Ethernet autoselect (100baseTX <full-duplex>) > status: active > nd6 options=3D29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL> > root@csbuild:~ # ifconfig ue0 inet "192.168.2.176" netmask "255.0.0.0" > root@csbuild:~ # ifconfig ue0 > ue0: flags=3D8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu = 1500 > options=3D80001<RXCSUM,LINKSTATE> > ether b8:27:eb:fd:58:69 > inet 192.168.2.176 netmask 0xff000000 broadcast = 192.255.255.255=20 > media: Ethernet autoselect (100baseTX <full-duplex>) > status: active > nd6 options=3D29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL> > root@csbuild:~ #=20 What exactly does ifconfig do? It seems to me that it reads the IP = address from the quoted string but truncates the netmask. Is this a bug = in ifconfig or intended behavior? Best wishes Jeremy=
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