On 02/08/2012 17:52, Johnny Hughes wrote: > On 08/02/2012 09:33 AM, Birta Levente wrote: >> On 02/08/2012 17:24, Johnny Hughes wrote: >>> On 08/02/2012 09:00 AM, Birta Levente wrote: >>>> Hi all >>>> >>>> Can someone explain me this: >>>> >>>> ifcfg-eth0-range1: >>>> ONBOOT="yes" >>>> IPADDR_START="192.168.1.48" >>>> IPADDR_END="192.168.1.55" >>>> CLONENUM_START="1" >>>> >>>> Why Bcast is 192.168.1.51 and why Mask is 255.255.255.252 ? >>>> >>>> OS: Centos 6.3/64bit >>>> >>>> >>>> Thanks >>>> >>>> Levi >>>> >>>> # ifconfig >>>> >>>> eth0:1 Link encap:Ethernet HWaddr 00:9C:02:99:FA:00 >>>> inet addr:192.168.1.48 Bcast:192.168.1.51 >>>> Mask:255.255.255.252 >>>> UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 >>>> Interrupt:16 Memory:fbee0000-fbf00000 >>>> >>>> eth0:2 Link encap:Ethernet HWaddr 00:9C:02:99:FA:00 >>>> inet addr:192.168.1.49 Bcast:192.168.1.51 >>>> Mask:255.255.255.252 >>>> UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 >>>> Interrupt:16 Memory:fbee0000-fbf00000 >>>> >>>> eth0:3 Link encap:Ethernet HWaddr 00:9C:02:99:FA:00 >>>> inet addr:192.168.1.50 Bcast:192.168.1.51 >>>> Mask:255.255.255.252 >>>> UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 >>>> Interrupt:16 Memory:fbee0000-fbf00000 >>>> >>>> eth0:4 Link encap:Ethernet HWaddr 00:9C:02:99:FA:00 >>>> inet addr:192.168.1.51 Bcast:192.168.1.51 >>>> Mask:255.255.255.252 >>>> UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 >>>> Interrupt:16 Memory:fbee0000-fbf00000 >>>> >>>> eth0:5 Link encap:Ethernet HWaddr 00:9C:02:99:FA:00 >>>> inet addr:192.168.1.52 Bcast:192.168.1.51 >>>> Mask:255.255.255.252 >>>> UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 >>>> Interrupt:16 Memory:fbee0000-fbf00000 >>>> >>>> eth0:6 Link encap:Ethernet HWaddr 00:9C:02:99:FA:00 >>>> inet addr:192.168.1.53 Bcast:192.168.1.51 >>>> Mask:255.255.255.252 >>>> UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 >>>> Interrupt:16 Memory:fbee0000-fbf00000 >>>> >>>> eth0:7 Link encap:Ethernet HWaddr 00:9C:02:99:FA:00 >>>> inet addr:192.168.1.54 Bcast:192.168.1.51 >>>> Mask:255.255.255.252 >>>> UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 >>>> Interrupt:16 Memory:fbee0000-fbf00000 >>>> >>>> eth0:8 Link encap:Ethernet HWaddr 00:9C:02:99:FA:00 >>>> inet addr:192.168.1.55 Bcast:192.168.1.51 >>>> Mask:255.255.255.252 >>>> UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 >>>> Interrupt:16 Memory:fbee0000-fbf00000 >>> That is obviously not going to work ... a 255.255.255.252 mask is a 4 IP >>> subnet, with only 2 usable addresses and a network number and a >>> broadcast address. The only free addresses in >>> 192.168.1.48/255.255.255.252 are .49 and .50 >>> >>> The Broadcast and Mask settings are likely in your ifcfg-eth0 file and >>> not in the range file at all. >>> >>> The Mask would either be set manually in ifcfg-eth0 ... or by the DHCP >>> server if you get DHCP. The Broadcast address would automatically be set >>> based on the Mask, unless it is overridden in ifcfg-eth0. >>> >>> If the address is set via DHCP, you need to change the subnet mask on >>> the DHCP server as that is where it comes from. >>> >>> If you want 8 usable addresses (including the Network number, a gateway >>> address, and a Broadcast address), that would mean you need at least 11 >>> IPs in that subnet ... the closest fit would be a 255.255.255.240 subnet >>> (which has 16 addresses). If you were to want to use th 255.255.255.240 >>> subnet, then 192.168.1.48 would not be available as it would the the >>> Network number for that subnet ... the usable addresses would be >>> 192.168.1.49-63 that case and the Broadcast Address would be 192.168.1.64 >>> >>> Since this is on a private network, why are you not just using the full >>> 192.168.1.0 network with a 255.255.255.0 subnet? >>> >>> I guess the real question is, what are you trying to do :D >>> >>> >>> >>> >>> >>> >>> _______________________________________________ >>> CentOS mailing list >>> CentOS@centos.org >>> http://lists.centos.org/mailman/listinfo/centos >>> >> I have eth0 with public IP, netmask is 255.255.255.252. >> Additionally I own 8 public IPs xxx.xxx.xxx.48-55 with class subnet mask >> 255.255.255.248 >> >> If I set up with ifconfig eth:(0 to 7) xxx.xxx.xxx.(48-55) netmask >> 255.255.255.255 it's work. >> >> But if I set up the ifcfg-eth0:(0-7) files with the same IP and netmask >> it's not work. ifconfig show me the 255.255.255.252 netmask even if in >> file other netmask is specified. >> The same situation in ifcfg-eth0-range1 case. > > What if you do this: > > ifcfg-eth0-range1: > ONBOOT="yes" > IPADDR_START="192.168.1.49" > IPADDR_END="192.168.1.54" > CLONENUM_START="1" > BROADCAST=192.168.1.55 > NETMASK=255.255.255.248 > NETWORK=192.168.1.48 > > (with a .248 subnet, you can not use the first address (192.168.1.48) or > the last address (192.168.1.55) on a device, they are the Network > Address and the Broadcast Address ... so an 8 IP subnet has 6 usable > addresses. Also, one of those 6 addresses will also need to be assigned > to the gateway router if you need to talk to another network, so you > really only have 5 addresses that you can assign for use). > > > > > _______________________________________________ > CentOS mailing list > CentOS@centos.org > http://lists.centos.org/mailman/listinfo/centos >
Nope.... Work only .49 and .50 I bought 8 public IP-s ... so 8 IPs have to get work. In the hosting specification this IPs is usable with xxx.xxx.xxx.48-55 with subnet mask 255.255.255.255 with no gateway. As I sad, works perfectly with this command (8 times, of course :) ): #ifconfig eth:(0 to 7) xxx.xxx.xxx.(48-55) netmask 255.255.255.255 Thanks Levi _______________________________________________ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
