tsch157

updated

9 years ago

T

tsch157

8 Posts

0

7387

December 5th, 2017 00:00

Only allow specific IPs on VLAN

Hello,

I have a PowerConnect 6248 and I want to create a VLAN that only allows specific IPs to run. Port 1 is Uplink to the network configured as general port with VLAN 1 and 11. This is the connection to the network where I get the IPs assigned from I am allowed to use. Devices I connect to the switch right now can generally use all these IPs. 

To achieve my goal I created a new VLAN (11) and used the vlan association subnet function to assing IPs to the VLAN which should be allowed. Port 2 is connected with a server which is only allowed to use these IPs I assigned to the VLAN, so I configured Port 2 as general port with VLAN 11 allowed. Though I can still use all IPs. Also VLAN 1 is allowed on that port, otherwise I do not get anything online. When I remove VLAN 11 from Uplink port I also go offline on Port 2. Can you explain me how to achieve what I want?

Greetings!

  • tsch157

    8 Posts

    5690

    0

    Posted December 5th, 2017 09:00

    Hello,

    thank you for your answer. In general what I want to achieve is pretty easy in theory, but I do not know how to configure it exactly. Basically I do not need any VLAN tagging, I only want to make sure that on specific ports only specific IPs or subnets are allowed.

    Lets assume I have 10.0.1.0/24 and 10.0.2.0/24 avaliable on the switch. Now I want to make sure that for example on Port 2 a device behind it can only assing IPs in range of 10.0.1.0/27 and a device on Port 3 can only assing lets say the single addresses 10.0.1.100 and 10.0.2.100. Ideally all devices with these individual assignments are in their own VLAN.

    So I went the way that I create an own VLAN for each port and then use the vlan association subnet function to assign IPs or subnets to each VLAN for each port, but as I read this is not the way it works, right? Or am I just doing something wrong with the configuration of the VLANs.

    Greetings!

  • tsch157

    8 Posts

    5690

    0

    Posted December 5th, 2017 10:00

    Fully static IP addresses. They are always set manually.

  • tsch157

    8 Posts

    5707

    0

    Posted December 5th, 2017 11:00

    Thank you for your answer. This is what I tried already as well. As soon as I set the ports to access mode with the VLAN I configured for the IPs I want to have assigned I do not get connection anymore.

    The Uplink is always configured as general port with VLAN 1 and the additional VLANs for each of my ports.

    Greetings!

  • tsch157

    8 Posts

    5706

    0

    Posted December 5th, 2017 11:00

    Thank you for your answer and your help!

    The relevant configuration is currently like this:

    console#show running-config

    !Current Configuration:
    !System Description "PowerConnect 6248, 3.3.16.1, VxWorks 6.5"
    !System Software Version 3.3.16.1
    !Cut-through mode is configured as disabled
    !
    configure
    vlan database
    vlan 11
    vlan association subnet XXX.230.163.0 255.255.255.248 11
    vlan association subnet XXX.230.163.10 255.255.255.255 11

    description "Uplink"
    switchport mode general
    switchport general allowed vlan add 11
    exit
    !

    interface ethernet 1/g34
    negotiation 100h
    description "INET"
    switchport mode general
    switchport general allowed vlan add 11
    exit
    !
    interface ethernet 1/g35
    negotiation 100h


    description "iLo"
    switchport mode general
    switchport general allowed vlan add 11
    exit

    I tested it by pinging external from the internet. I´m working with external IP addresses. I did not ping from device to device only trough the switch.

    Greetings!

  • tsch157

    8 Posts

    1611

    0

    Posted December 5th, 2017 13:00

    Hello,

    thank you alot for your very detailed description. The problem I have is that I generally have absolutely no control of the configuration of the gateway. I can tell which configuration I need, but they are most likely not able to configure my VLANs on their infrastrcture. I´m in a data center and have the uplink provided together with all external ip addresses I´m allowed to use.

     I just want to make sure that IP addresses are bound to specific ports, so I´m able to ensure that clients on a port can only use the IPs I want them to use. This means I´m only able to operate within the PowerConnect6248. Is it possible to perform this routing with the switch maybe with something like inter vlan routing?

    Greetings!

  • tsch157

    8 Posts

    1611

    0

    Posted December 5th, 2017 15:00

    Thank you for your reply. Currently no VLANs are in use but VLAN 1, so I´m already running on a flat network. The only reason applying VLANs for me was my intension to limit IP addresses on a port. I also have no idea about the gateways hardware, I´m sorry. Currently it is just Uplink -> 6248 -> Clients.

    So my way would be that I create an IP ACL for each port to ensure that only the IPs/Subnets I specify there are usable. How is the syntax here? Do I need to allow the IPs I want in first place and deny all others afterwards or do I just need my allow rule?

    Greetings!

    -> UPDATE

    I just tried it out and I set the following configuration for a Port which is only expected to use one single IP:

    interface ethernet 1/g35
    negotiation 100h
    description "iLo"
    ip access-group deny out 11
    ip access-group deny in 10
    ip access-group iLo in 9
    ip access-group iLo out 8
    exit

    Deny is set to deny IP Protocol from 0.0.0.0. 0.0.0.0 so everything.

    After that I set rule iLo to permit the specific IP I want once inbound and outbound with a higher priority. The result is that after I did the deny nothing was pinging, and after I applied the permit with rule iLo it was pinging again. So this is most likely what you suggested and I guess this solved my problem.

    I will try this tomorrow on another interface with a server behind which is virtualized and uses several IPs to finally confirm this. So I can test it by applying foreign IPs I do not allow with ACL to a Linux VM and see if it gets a connection. (It´s really late here already). I will come back and share my results, but I´m very confident that this is exactly what I needed. Thank you so much!

    Greetings!

  • tsch157

    8 Posts

    1611

    0

    Posted December 6th, 2017 03:00

    Hello!

    As a summary in case this is relevant for anyone else:

    I configured one ACL like this:

    console(config)# access-list test permit ip 192.230.163.0 0.0.0.7 0.0.0.0 255.255.255.255

    This will allow subnet 192.230.163.0/29 to be reachable by 0.0.0.0/0 (everything)

    After that the rule named test just needs to be applied to a port:

    console(config-if)# ip access-group test

    Thats it, only ip packets matching this rule will be able to be transfered. Everything else will be dropped.