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How do I bind a bunch of /24 subnets (secondary) in one shot in Ubuntu 14?

Bashed Posts: 4
edited November 2016 in Network Management

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I need to bind a bunch of /24 IPv4 subnets as secondary. The primary /29 is already set during the installation of Ubuntu 14x. How do I bind the remainder /24 subnets in one shot instead of individual single IPs one at a time?

I tried this method by adding the below line in /etc/network/interfaces but it didn't work?


up route add [-net|-host] <host/net>/<mask> gw <host/IP> dev <Interface> root@server:~# /etc/init.d/networking restart

I also tried this method too (below example, but did actual IPs and em1)

for i in {1..128}; do echo iface eth1:$i inet static >> /etc/network/interfaces; echo address 192.168.0.$i >> /etc/network/interfaces; echo netmask >> /etc/network/interfaces; echo auto eth1:$i >> /etc/network/interfaces; done

root@server:~# service networking restart stop: Job failed while stopping start: Job is already running: networking root@server:~# ifdown em1 && sudo ifup em1

IPs still don't ping however. They're 100% routed correctly on the Cisco switch though.


  • saqman2060
    saqman2060 Posts: 777
    edited November 2016

    I don't have a lot of experience subnetting networks. What I will do and relay this message to a more experienced technician and see if they can come up with a solution.

  • Trying to bind 20 x /24 subnets in Ubuntu 14 Server (for proxy/VPN) but I'm stuck here. These are diversified /24 subnets.

    I tried the below method via script called addips.sh

    for i in $(seq 3 254); do echo "auto em1:$i iface em1:$i inet static address xxx.xxx.16.$i netmask " >> virthosts; done

    But, I noticed that this happened now:

    Each /24 subnet it outputted started off at #1 again instead of 255, 256, 257, etc all the way through consecutively for all 20 x /24 subnets

    auto em1:1 auto em1:254 Then again... auto em1:1 ...

    How can I properly change this so it does reset at #1? em1 is the NIC Ethernet port (primary) and only port used too.     

    I also want to make sure these are permanent, they stick after a server reboot.

  • Anyone?

  • I just asked a few linux experts on linkedin to see if they have suggestions.

  • saqman2060
    saqman2060 Posts: 777
    edited November 2016

    The experts that I consulted with have respond and they ask if you can clarify in clear details what you are trying to accomplish. 

    They suggested you draw out a datagram of this ideal network. This will allow them to visually see your idea in action and to notify you of any pitfalls along the way.

    This Ubuntu you have, is it a DHCP? Are you using a static IP address on the server, and where are the /24 IP addresses coming from, a router, another server? Perhaps you are trying to combine network addresses from other gateways on this one server using some kind of ARP list so the server acts as a link to all the other gateways allowing all addresses to communicate with one another. Again, this is my guess, if you can walk us through your setup step-by-step, we can better help.

    Please, tell us everything you are trying to do and why you are doing it. How was the original IP on ubuntu setup, by you or an admin? Give us all the details.


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