Date: Thu, 15 Sep 2005 09:31:20 -0400 (EDT) From: Jerry McAllister <jerrymc@clunix.cl.msu.edu> To: gpeel@thenetnow.com Cc: freebsd-questions@freebsd.org, John Oxley <john@yoafrica.com> Subject: Re: IPs , Netmasks and Broadcast. Message-ID: <200509151331.j8FDVKCW008881@clunix.cl.msu.edu> In-Reply-To: <008601c5b9f6$f3578620$6501a8c0@GRANT>
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> > Jerry, > > I apologise. Its late in the day for me and the email addresses are blending > into one :-) > > Anyways, so the examples I put together are correct. Good. So I wonder why, > the 1 IP I have, won't work with the real netmask, but only with the 255. > One more item of note, I see in dmesg that when it tries to apply it, the > message: Look carefully. I changed one thing in each group. Also, if you have a block of 128, your main mask would probably not be 255.255.2555.0. I think it would be 255.255.255.128. Anyway, all the aliases for any one NIC card must be 255.255.255.255. > > arplookup xxx.xxx.xxx.xxx failed: host is not on local network Probably because the ifconfig didn't work right with the wrong netmasks. > -Grant > > P.S. This is a small block, only 30 ips. The other 29, including 1 with the > real netmask, is on another machine working fine, right beside the machine I > am referencing. You will have to calculate the mask somewhat based on the switch/router segment you are on. It is too early for me to think it out. ////jerry > > > ----- Original Message ----- > From: "Jerry McAllister" <jerrymc@clunix.cl.msu.edu> > To: <gpeel@thenetnow.com> > Cc: "John Oxley" <john@yoafrica.com>; <freebsd-questions@freebsd.org> > Sent: Thursday, September 15, 2005 8:56 AM > Subject: Re: IPs , Netmasks and Broadcast. > > > >> > >> Thanks John, > >> > >> What you are saying make perfect sense based on what I've had to do in > >> the > >> past. Just to clarify ... > >> > >> Lets say I have 5 machines (which I do) > >> > >> And lets say I have 10 blocks of IP address from my upline (which I do) > >> > >> 1.1.1.1/24 > >> 2.2.2.2/24 > >> 3.3.3.3/24 > >> 4.4.4.4/24 > >> ... > >> > >> And, lets say that I need to set up various IPs, from each of the groups > >> above, on all 5 of the servers. > >> > >> To keep the explanation easy to follow, I will put what I might have in > >> rc.conf for each machine, Leaving out the gateway IPs as they are not > >> realevent to the question...my router setting work fine. > > > > No, this is not what I said. I don't know if anyone else has posted > > on this since then. But, > > > > The next two chunks below represent what I said. > > > > ////jerry > > > > Sever 1: > > > > hostname="machine1.mydomain.com" > > defaultrouter="some ip here" > > ifconfig_em0="inet 1.1.1.2 netmask 255.255.255.0" > > ifconfig_em0_alias0="inet 1.1.1.3 netmask 255.255.255.255" > > ifconfig_em0_alias1="inet 1.1.1.4 netmask 255.255.255.255" > > ... > > ifconfig_em0_alias2="inet 2.2.2.3 netmask 255.255.255.255" > > ifconfig_em0_alias3="inet 2.2.2.4 netmask 255.255.255.255" > > ifconfig_em0_alias4="inet 2.2.2.5 netmask 255.255.255.255" > > ... > > ifconfig_em0_alias5="inet 3.3.3.4 netmask 255.255.255.255" > > ifconfig_em0_alias6="inet 3.3.3.5 netmask 255.255.255.255" > > ifconfig_em0_alias7="inet 3.3.3.6 netmask 255.255.255.255" > > ... > > > > Sever 2: > > > > hostname="machine2.mydomain.com" > > defaultrouter="some ip here" > > ifconfig_em0="inet 1.1.1.5 netmask 255.255.255.0" > > ifconfig_em0_alias0="inet 1.1.1.6 netmask 255.255.255.255" > > ifconfig_em0_alias1="inet 1.1.1.7 netmask 255.255.255.255" > > ... > > ifconfig_em0_alias2="inet 2.2.2.6 netmask 255.255.255.255" > > ifconfig_em0_alias3="inet 2.2.2.7 netmask 255.255.255.255" > > ifconfig_em0_alias4="inet 2.2.2.8 netmask 255.255.255.255" > > ... > > ifconfig_em0_alias5="inet 3.3.3.7 netmask 255.255.255.255" > > ifconfig_em0_alias6="inet 3.3.3.8 netmask 255.255.255.255" > > ifconfig_em0_alias7="inet 3.3.3.9 netmask 255.255.255.255" > > ... > > > > > > ----------------------------------------------------------------- > > > > Sever 1: > >> > >> hostname="machine1.mydomain.com" > >> defaultrouter="some ip here" > >> ifconfig_em0="inet 1.1.1.2 netmask 255.255.255.0" > >> ifconfig_em0_alias0="inet 1.1.1.3 netmask 255.255.255.255" > >> ifconfig_em0_alias1="inet 1.1.1.4 netmask 255.255.255.255" > >> ... > >> ifconfig_em0_alias2="inet 2.2.2.3 netmask 255.255.255.0" > >> ifconfig_em0_alias3="inet 2.2.2.4 netmask 255.255.255.255" > >> ifconfig_em0_alias4="inet 2.2.2.5 netmask 255.255.255.255" > >> ... > >> ifconfig_em0_alias5="inet 3.3.3.4 netmask 255.255.255.0" > >> ifconfig_em0_alias6="inet 3.3.3.5 netmask 255.255.255.255" > >> ifconfig_em0_alias7="inet 3.3.3.6 netmask 255.255.255.255" > >> ... > >> > >> > >> Sever 2: > >> > >> hostname="machine2.mydomain.com" > >> defaultrouter="some ip here" > >> ifconfig_em0="inet 1.1.1.5 netmask 255.255.255.0" > >> ifconfig_em0_alias0="inet 1.1.1.6 netmask 255.255.255.255" > >> ifconfig_em0_alias1="inet 1.1.1.7 netmask 255.255.255.255" > >> ... > >> ifconfig_em0_alias2="inet 2.2.2.6 netmask 255.255.255.0" > >> ifconfig_em0_alias3="inet 2.2.2.7 netmask 255.255.255.255" > >> ifconfig_em0_alias4="inet 2.2.2.8 netmask 255.255.255.255" > >> ... > >> ifconfig_em0_alias5="inet 3.3.3.7 netmask 255.255.255.0" > >> ifconfig_em0_alias6="inet 3.3.3.8 netmask 255.255.255.255" > >> ifconfig_em0_alias7="inet 3.3.3.9 netmask 255.255.255.255" > >> ... > >> > >> Sever 2: > >> > >> hostname="machine3.mydomain.com" > >> defaultrouter="some ip here" > >> ifconfig_em0="inet 1.1.1.8 netmask 255.255.255.0" > >> ifconfig_em0_alias0="inet 1.1.1.9 netmask 255.255.255.255" > >> ifconfig_em0_alias1="inet 1.1.1.10 netmask 255.255.255.255" > >> ... > >> ifconfig_em0_alias2="inet 2.2.2.9 netmask 255.255.255.0" > >> ifconfig_em0_alias3="inet 2.2.2.10 netmask 255.255.255.255" > >> ifconfig_em0_alias4="inet 2.2.2.11 netmask 255.255.255.255" > >> ... > >> ifconfig_em0_alias5="inet 3.3.3.10 netmask 255.255.255.0" > >> ifconfig_em0_alias6="inet 3.3.3.11 netmask 255.255.255.255" > >> ifconfig_em0_alias7="inet 3.3.3.12 netmask 255.255.255.255" > >> ... > >> > >> Server 3, 4 and 5 similar with repeating patterns. > >> > >> So the original question was: When setting up an IP from any given block, > >> do, or should I, need to use the real netmask that my ISP has assinged me > >> (for the first), then, the single host (255) netmask for each of the rest > >> (Again, from a specific IP block? > >> > >> I hope it is because I have hundreds of IPs set up that way. > >> > >> The reason I ask this question (again) is because I have one IP that does > >> not want to work using the above paradigm. That is to say, that it IS the > >> only IP from a specific block, on a particular machine, and it won't take > >> using the real netmask, it will only work using the 255 netmask. > >> > >> Sincerly, > >> > >> -Confused > >> (Grant). > >> > >> > >> > >> > >> > >> > >> > >> ----- Original Message ----- > >> From: "John Oxley" <john@yoafrica.com> > >> To: "Grant Peel" <gpeel@thenetnow.com> > >> Cc: <freebsd-questions@freebsd.org> > >> Sent: Thursday, September 15, 2005 7:55 AM > >> Subject: Re: IPs , Netmasks and Broadcast. > >> > >> > >> > On Wed, Sep 14, 2005 at 12:00:12PM -0400, Grant Peel wrote: > >> >> Now I am really confused. > >> > First of all install ipcalc NOW. > >> > > >> >> Up until this morning I thought I had a good handle on when I need to > >> >> use > >> >> the real Netmask and Broadcast. > >> >> > >> >> For example, If I have 3 servers, and my upline asigns me a block of > >> >> 128 > >> >> addresses, for the first ip used (from this block) on each server, I > >> >> would > >> >> need to specify the IP, true netmask and a broadcase. Then, when using > >> >> more > >> >> IPs from that block, I would use a 255.255.255.255 netmask and a > >> >> broadcast > >> >> equal to the IP. > >> > > >> > No, a 255.255.255.255 netmask specifies a single host. If your ISP has > >> > given you 128 IPs, that is a /25 or netmask 255.255.255.128 as shown : > >> > sysjo@hades:~$ ipcalc 192.168.254.0/25 > >> > Address: 192.168.254.0 11000000.10101000.11111110.0 0000000 > >> > Netmask: 255.255.255.128 = 25 11111111.11111111.11111111.1 0000000 > >> > Wildcard: 0.0.0.127 00000000.00000000.00000000.0 1111111 > >> > => > >> > Network: 192.168.254.0/25 11000000.10101000.11111110.0 0000000 > >> > HostMin: 192.168.254.1 11000000.10101000.11111110.0 0000001 > >> > HostMax: 192.168.254.126 11000000.10101000.11111110.0 1111110 > >> > Broadcast: 192.168.254.127 11000000.10101000.11111110.0 1111111 > >> > Hosts/Net: 126 Class C, Private Internet > >> > > >> > So all your machines would have the same network and broadcast, and you > >> > would make them all use your gateway box as the default route. > >> > > >> > As you can see, a 255.255.255.255 netmask (/32) is only one host: > >> > sysjo@hades:~$ ipcalc 192.168.254.34/32 > >> > Address: 192.168.254.34 11000000.10101000.11111110.00100010 > >> > Netmask: 255.255.255.255 = 32 11111111.11111111.11111111.11111111 > >> > Wildcard: 0.0.0.0 00000000.00000000.00000000.00000000 > >> > => > >> > Hostroute: 192.168.254.34 11000000.10101000.11111110.00100010 > >> > Hosts/Net: 1 Class C, Private Internet > >> > > >> > > >> > What you need to do is use IP calc to see what the network and > >> > broadcast > >> > are and set those, although on FreeBSD 4.X (I think anyway, someone > >> > correct me if I am wrong) you can just put in your /etc/rc.conf > >> > ifconfig_bge0="inet 192.168.254.32/25" > >> > or > >> > ifconfig_bge0="inet 192.168.254.32 netmask 255.255.255.128" > >> > > >> > And FreeBSD will work out the network and broadcast for you. > >> > > >> >> Today, I was in this exact position where I was tring to add an (the > >> >> first > >> >> one one THAT machine, from that block) IP from a block that is almost > >> >> completely used up on another server, and the one I was adding it to > >> >> would > >> >> not take it. When I tried adding it with a 255.255.255.255 netmask, > >> >> and a > >> >> broadcast eaqual to the amount of IPs from that block - it worked. > >> > > >> > Like I said before, there is only 1 IP in a /32 block, and the > >> > broadcast > >> > will be either a.b.c.127 or a.b.c.255 depending whether you have the > >> > first or second subnet inside that class C. > >> > > >> > Hope this helps > >> > > >> > -John > >> > > >> > > >> > >> > >> _______________________________________________ > >> freebsd-questions@freebsd.org mailing list > >> http://lists.freebsd.org/mailman/listinfo/freebsd-questions > >> To unsubscribe, send any mail to > >> "freebsd-questions-unsubscribe@freebsd.org" > >> > > > > > > > > > _______________________________________________ > freebsd-questions@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-questions > To unsubscribe, send any mail to "freebsd-questions-unsubscribe@freebsd.org" >
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