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Date: Sun, 28 Feb 1999 11:32:49 +0900 (JST)
From: Minoru Oikawa <mino@bb.imagica.co.jp>
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Subject: [FreeBSD-net-jp 1398] Re: subnetmask
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 $B$*$$$+$o(B@IMAGICA $B$G$9!#$b$R$H$D=q$$$F$*$3$&$+$J!#(B

> Date: Sat, 27 Feb 1999 23:47:23 +0900
> From: "Kono Ken'ichi" <s96355kk@sfc.keio.ac.jp>
> Message-Id: <36D8057B3AC.5174S96355KK@ma4.justnet.ne.jp>

> -----$BA0Ds>r7o(B-----
> $B!!(B192.168.0.0/20$B!!$J%M%C%H%o!<%/$rNc$K$7$^$9!#(B
> 
> $B!!(BNIS/NFS$B$,F3F~$5$l$F$$$F!"(B300$B0J>e$N%[%9%H$,B8:_$9$k$b$N$H$7$^$9!#(B
> 
> $B!!%k!<%?!<$O!"%/%i%9%U%k%k!<%F%#%s%0%W%m%H%3%k$rC}$k$3$H$,=PMh$k$b$N$r(B
> $B;H$C$F$k$3$H$H$7$^$9!#(B
> 
> $B!!BeM}(BARP$B$N5!G=$,$"$j!"2DJQD9%5%V%M%C%H%^%9%/$K$bBP1~$7$F$$$k$b$N$H$7$^$9!#(B
> ------------------

 $B$&$%$%!D(B
 $B!V(BVLSM $B$KBP1~$7$F$$$k%k!<%?!W$H$$$&$N$,=P$FMh$F$F!"(B
$B!V(Bclassful $B%k!<%F%#%s%0%W%m%H%3%k$rC}$k$3$H$,(B*$B=PMh$k(B*$B!W$C$F!D(B

$B!V(Bclassless $B%k!<%F%#%s%0%W%m%H%3%k$rC}$k$3$H$,=PMh$J$$!W$H$+!"(B
$B!V(Bclassful $B%k!<%F%#%s%0%W%m%H%3%k$7$+C}$i$l$J$$!W$H$+!#(B

# classful == classic, historic $B$H$$$&$3$H$J$s$G$9$,(B
 
> $B%[%9%H#1(B
> ip address  192.168.36 .33
> subnet mask 255.255.254.0
> 
> $B%[%9%H(B2$B!J(B2$BKg$N(BNIC$B$,AuCe$5$l$F$$$F!"%5%V%M%C%H!"%5%V%I%a%$%s$,(B
> $B!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!3d$jEv$F$i$l$F$$$^$9!K(B
> ip address  192.168.36 .55
> subnet mask 255.255.254.0
> 
> ip address  192.168.172.224/27
> subnet mask 255.255.255.224

 $BA0Ds>r7o$K$O(B /20 $B$H$@$1=q$$$F$"$k$s$G$9$1$I(B?
 /20 $B$r(B subnet $B2=$7$F;H$C$F$$$k!"$NA0Ds>r7o$,0EL[$K$J$5$l$F(B
$B$$$k!"$H$$$&M}2r$rMW5a$7$F$$$k$C$F$3$H(B?

 /masklen $B$N5-K!$H(B mask $B$r$0$A$c$0$A$c$K:.$<$F=q$/$N$ONI$/$J(B
$B$$$G$9!#$I$C$A$+$K$9$k!"$b$7$/$OA4$FJ;5-$9$k!#(B

>  $B<B:]$N%5%V%M%C%H%^%9%/$O!"(B255.255.254.0$B!!$J$s$G$9$,!"4V0c$C$F(B
> 255.255.255.0$B!!$r@_Dj$7$F$7$^$$$^$7$?!#(B
> 
>  $B$G$b!"$A$c$s$H%M%C%H%o!<%/!J%j%s%/%9%F!<%H!K$O3NN)$5$l$F$$$F!"(B

 $B$3$l!"2?(B?
 $B2?$G2?$rD4$Y$?$+=q$+$J$$$H(B context $B$K$h$C$FH=CG$9$k$3$H$9$i(B
$B$b=PMh$J$$$G$9$,!#%j%s%/%9%F!<%H!"$C$F$3$H$O(B netstat -f inet
$B$N7k2L$H$7$F!"$C$FM}2r$9$l$P$h$$$N(B?

> $BC<Kv#1$NB0$9$k%;%0%a%s%H$O$b$A$m$s!"$=$N30$K=P$k$3$H$b=PMh$^$9(B

 $B5U$J$i!"FCDj$N>r7o$G%H%i%V%k$K$J$k$s$@$m$&$1$I!#(B

> $B!!$3$l$O!"KM$,!"(B/etc/rc.conf$B!!$K$*$$$F!"(Bdefault wateway$B!!(B192.168.36.1$B!!$r(B
> $B@_Dj$7$F$$$k$+$i$@$H;W$$$^$9!#!J(BFreeBSD2.2.8Release$B$r;HMQ$7$F$$$^$9(B) 

 $B$o$+$i$J$$!#(B
 $B$3$N%M%C%H%o!<%/$N>\:Y$,2?=h$K$b=P$FMh$F$J$$$+$i!#(B

> $B!!$G$9$,!"%[%9%H(B1$B!J(B192.168.36.33$B!K$dF1%;%0%a%s%H!J(B192.168.36.0$B!K$KB0$9$k(B
> $B%[%9%H0J30$N%[%9%H$+$i2?$G%[%9%H#1$K%"%/%;%9$G$-$k$N$G$7$g$&$+!)(B

 arp $B$,5!G=$7$F$$$k$+$i!#(B
 /24 $B$H8m$C$F$$$F$b!"F10l$H$_$J$5$l$k%M%C%H%o!<%/$KB0$7$F$$(B
$B$k$+$i!#(B

> $B!!%5%V%M%C%H%^%9%/$O;2>H$7$F$$$J$/$F$H$$$&$3$H$G$7$g$&$+!)(B

 $B!V$7$F$$$J$/$F!W2?$G$9$C$F(B? $B0UL#ITL@$C$9$h!#(B

> $B2>$KE,Ev$J%5%V%M%C%H%^%9%/!!(B 255.0.0.0$B!!$H@_Dj$7$?$H$7$F$b30$+$i$bCf$+$i(B
> $B$bF1MM$K%"%/%;%9$G$-$k$N$G$7$g$&$+!)(B

 $B30$+$i(B ICMP $BEj$2$F$b!"$^$:3N<B$KJV;v$OMh$J$$$G$9$M!#(B
 $BFbB&$+$i$@$H(B IP $B$N<BAu$K0M$k$N$+$J!#(B

 $B$3$l$rD4$Y$?$+$C$?$i!"(B

A. /23 $B$J%M%C%H%o!<%/$KFsBf$N%[%9%H$rN)$A>e$2$k!#(B
B. $B$=$l$>$l$K!"(B

	10.0.20.3/24
	10.0.21.3/24

  $B$J$I$H@_Dj$7$F$d$C$F!"(B
C. arp $B$NMM;R$r4Q;!!#(B

 $BN;2r(B?
 $B@8$-$F$k4{B8%M%C%H%o!<%/$K7R$$$8$c%@%a$@$h!#LBOG$@$+$i$M!#(B

 $B:#!"<B:]$K(B ifconfig $B$G@5$7$/$J$$(B netmask $B$r@_Dj$7$F<B83$7$^(B
$B$7$?$1$I!"(BFreeBSD 2.2.8-19990116-SNAP $B$J%[%9%H$N>l9g$@$H!"$U(B
$B$D$&$K5!G=$7$F$^$9!#(B

 $B$D$^$j$A$c$s$H%M%C%H%^%9%/$,:G=i$NH=CG4p=`$K$J$C$F$$$k$h$&(B
$B$K8+$($^$9!#%M%C%H%^%9%/$rL5;k$7$F(B arp $B$9$k$h$&$JLBOG$J<BAu(B
$B$K$O$J$C$F$$$^$;$s$M!#(B
 $BLBOG$J<BAu$K$O!"%M%C%H%^%9%/$,$:$l$F$$$F$b5!G=$9$k$H$$$&Mx(B
$BE@$,$"$j$^$9$1$I!"%V%m!<%I%-%c%9%H$,A}$($^$/$j!#(B

>   $B$=$NM}M3$O!"(BNIS$B$+!"(BDNS$B$+$,5!G=$7$?7k2L$G$7$g$&$+!)(B

 $B0c$&!#$^$C$?$/4X78$J$$!#(B

> $BBeM}(BARP$B$O4X78$J$$$G$9$h$M!)(B

 $BMxMQ$7$F$J$$$J$i4X78$J$$!#(B

--- mino
