Date: Thu, 15 Sep 2005 10:30:37 -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: <200509151430.j8FEUb2a009094@clunix.cl.msu.edu> In-Reply-To: <013501c5b9fc$47aec3a0$6501a8c0@GRANT>
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> > Jerry, > > I see, you changed the real netmask in the second and third group to 255. No, I changed the alias' netmask, not the "real" one. > Hmm, I went through this before, and unless I added 1 ip from each block > with the real netmask, the ip wouldnt take. > > FYI when my ISP sends me a new block, they always give me the network, > router, broadcas address etc and I run them through ip calc, and they are > always correct. > > Either way, I better revisit the Handbook/Manpage as it seems that I am > asking the same question(s) that I thought were answered 5 years ago... that is always a good idea. ////jerry > > Thanks for the help Jerry, > > -Grant > > ----- Original Message ----- > From: "Jerry McAllister" <jerrymc@clunix.cl.msu.edu> > To: <gpeel@thenetnow.com> > Cc: <freebsd-questions@freebsd.org>; "John Oxley" <john@yoafrica.com> > Sent: Thursday, September 15, 2005 9:31 AM > Subject: Re: IPs , Netmasks and Broadcast. > > > >> > >> 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" > >> > > > > > > > > > _______________________________________________ > 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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