Lets consider a scenario
I have two system A and B
IP Address A - 192.168.0.1 database IP is 192.168.0.1 for pacs
IP Address B - 192.168.0.2 database IP is 192.168.0.2 for pacs
I have sent dicom image in A using dcmsnd command
how to access system A data from system B
So what i need to configure in system A or system B to access system A's dicom data in system B
I can recommend two options depending on your needs.
Option 1
The first option assumes you do actually want redundant data (ie: two separate storage locations and two separate databases) and not just two dcm4chee instances.
In this case you can set up dicom forwarding from A to B. This is setup in the Forward Service bean of dcm4chee (via the jmx-console or via the jboss twiddle.sh script). More complex forwarding (ie: based on modalities) can be configured in the Forward Service2 bean.
The official docs are here:
Forward Service
Forward Service2
If you need more details, I have written a blog post that goes into more depth about using and setting up Forward Service here:
DCM4CHEE: PACS SYNCHRONIZATION VIA DICOM FORWARDING
Option 2
The second option assumes you don't really need data redundancy, but you do need two separate dcm4chee instances.
No problem. You can setup two dcm4chee instances on separate boxes to share the same database (which lives either at 192.168.0.1 or 192.168.0.2 or perhaps somewhere else) and storage device.
For this to really work, you will need to configure both dcm4chee instances to not only connect to the same db, but to also store their archives on the same shared network storage device which you mount on each box.
The storage directory is configured via the DefaultStorageDirectory property of the FileSystemMgt group=ONLINE_STORAGE bean in the jmx-console.
Note: My answer assumes the dcm4chee-2.x series, and not the successor arc-light series (though the steps should be conceptually similar in either case - ie: setup forwarding or shared storage).
Related
I am looking for a basic thing yet I have not found not even a single good documentation on getting it done.
I want to allocate a floating IP, then associate it to a network interface of a droplet other than eth0.
The reason is I want to have the ability to very easily switch from one IP to the other with a programming language.
In a few words, I want to be able to do these two commands and both should provide a different response.
curl --interface eth0 https://icanhazip.com
curl --interface eth1 https://icanhazip.com
Also, I want to know what to do once I release the Floating IP, how do I roll back to the starting point.
All documentation I read, rely heavily on "ip route" and "route", most did not even work, some worked but replaced completely the old IP by the floating and that's not what I want, and also they did not show how to rollback the introduced configuration changes.
Please help, I spent 1 whole day now trying to get this to work for a project, and no results so far.
I guess there is no need to know DigitalOcean, how to make this work on other Cloud Providers would apply here too I think.
Update
After asking this on DigitalOcean community forum (https://www.digitalocean.com/community/questions/clear-guide-on-outbound-network-through-floating-ip), they claim that is not supported, although there may be some solutions to this if somebody can provide such a "hacky" solution I would take it too. Thanks
In the cloud (AWS. GCP etc.) ARP is emulated by the virtual network layer, meaning that only IPs assigned to VMs by the cloud platform can be resolved. Most of the L2 failover protocols do break for that reason. Even if ARP worked,the IP allocation process for these IPs (often called “floating IPs”) would not integrate with the virtual network in a standard way, so your OS can't just "grab" the IP using ARP and route the packets to itself.
I have not personally done this on Digital Ocean, but I assume that you can call the cloud's proprietary API to do this functionality if you would like to go this route.
See this link on GCP about floating IPs and their implementation. Hope this is helpful.
Here's an idea that needs to be tested:
Let's say you have Node1(10.1.1.1/24) and Node2(10.1.1.2/24)
Create a loopback interface on both VMs and set the same IP address for both like (10.2.1.1/32)
Start a heartbeat send/receive between them
When NodeA starts it automatically makes an API call to create a route for 10.2.1.1/32 and points to itself with preference 2
When NodeB starts it automatically makes an API call to create a route for 10.2.1.1/32 and points to itself with preference 1
The nodes could monitor each other to withdraw the static routes if the other fails. Ideally you would need a 3rd node to reach quorum and prevent split brain scenarios, but you get the idea right?
We are considering Riak for use in an embedded device context (embedded Linux) where devices are dynamically addressed (DHCP).
Is this a viable choice?
We can assume that appropriate auto-discovery protocols are in place to enable devices to discover each other. Upon joining the network, a device would obviously need to do a riak-admin cluster join <other device>. Other than this, would Riak be capable of handling devices leaving and re-joining the network on a fairly non-frequent basis? Or, does it play much more nicely in a statically-addressed environment?
DHCP doesn't necessarily mean the device has to join when it boots. If the node names are resolvable via DNS or hosts file, and the listeners are configured to 0.0.0.0, the Riak nodes should communicate quite happily even if their IPs change on reboot.
We're prototyping a jgroups-based cluster node messaging system that will replace one that was JDBC-based. There are a lot of folks in my organization who are concerned about adding more multicast traffic to an already busy network, so I'm getting some pushback on a UDP/multicast solution.
I know JGroups can be configured to be TCP only, but I do not want to have to force a configuration step into the application where each node has to be identified ahead of time in a config file.
What I'd like then is to see if we can get a hybrid working here where multicast is used ONLY for group membership operations (discovery, heartbeats, failure detection), but messaging is all TCP-based.
I'm not finding examples of that in my searches, however, and am therefore questioning whether JGroups can be configured this way.
Can it, and any example configs showing how?
Thanks!
As for discovery, using MPING you can do that - it uses IP multicast to discover new nodes, although these later respond via the main transport (TCP in your case).
As for FD/FD_ALL, I don't think it's possible, the protocols are designed to use the main transport. You'd have to write your own FD protocol, shouldn't be that complicated.
However, if you can use UDP, you probably should. It's up to you whether you send a message to one node, multiple ones or all of them - for one destination there will be unicast UDP, for few destinations (if you set the anycast option) will be multiple unicasts used and only for all nodes the UDP will reduce the network load by multicasting. It's really up to the application, UDP just allows multicasts.
I have a network of computers connected in form of a graph.
I want to ping from one computer(A) to another computer(B). A and B are connected to each other through many different ways, but I want to PING via only a particular edges only. I have the information of the edges to be followed during pinging available at both A and B.
How should I do this?
You could source route the ping but the return would choose its own path.
Furthermore, source-routed packets are often filtered due to security concerns. (Not always, they are useful and sometimes even required at edge routers.)
If the machines are under your local administrative control, then you could ensure that source-routed packets are permitted. As long as you are able to start a daemon on machine B, you could also easily enough design your own ping protocol that generates source-routed echo returns.
Well, this is actually done by routing protocols that are configured on the media in between the computers (routers I expect). I think there isn't a way where you can say "use that specific route". The routers have different protocols (OSPF, EIGRP, RIPv2) and they do the load balancing. The only way you would be sure of one specific route is to use static routing, but this isn't dynamically done where your computer decides the route.
This is normal because :
if you would be able to chose a route, DoS would be quite easy to do to kill one route.
Just a technical question -
Can two or more SNMP agents be run on the same port (on the same machine)?
My first instinct would be no since host:port identifies an instance of an application but I'm not sure.
Thank you!
Technically, if the OS supports it, the SO_REUSEADDR SO_REUSEPORT options may be set on a socket to allow other processes to bind to the same address/port and thus allow multiple processes to receive messages on the same address/port. But both processes would have to set the option, and I doubt any agent implementations do that because it would not make sense to do so--it would just cause headaches having both agents potentially responding to a single request. Managers won't be equipped to handle it.
However, you can instead run an SNMP proxy in the primary address/port, configured to forward requests to one of multiple agents based on query, security, or (with SNMPv3) context/engine ID parameters, and forward responses back.
Also, using AgentX, you have an SNMP master agent running on the primary address/port, and one or more SNMP sub-agents connected to the master agent. The master agent dispatches requests to the sub-agents as appropriate, merging the results into a single response, so that to the outside world it appears as a single agent. Each sub-agent typically handles a different branch of OID space (one sub-agent implementing certain module(s), another sub-agent implementing other module(s)).
But taking two agents intended to own the address/port exclusively, and forcing them to share through the REUSE options, while it may be possible, would not be wise.
You can run multiple agents on the same host and with the same port if they have differents ip address (can use a netsh script for that).
Personnaly I use the nsoftware ddl : SecureSNMP V8 edition .NET to do this.
You can look at this post : Multiple SNMP Agents with nsoftware dll
No, two agents cannot both run on the same port as seperate applications for the reasons you assumed (except with a brittle packet sniffing hack, which we'll not go into).
However, 2 agents can be accessed through the same port if there is some mechanism that handles the actual port and distributes requests based on MIB. For example the Windows SNMP service does this, allowing any number of SNMP agents to be added as "extensions" through the registry (HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SNMP\Parameters\ExtensionAgents) by writing them as DLLs and using the snmp.h headers in the platform SDK.
You are correct: ports can't be shared.
If both the agents were designed by you, then the answer can be different.
Consider the HTTP and FTP cases, we can use host names to distinguise multiple sites on the same port, then why can't we do it for SNMP?
We can create a dispatcher who monitors port 161 for incoming traffic. Then use multiple real agents to handle those traffic behind. We can feel free to design how to distinguise them. Personally I prefer the FTP virtual host name manner and use | to distinguise agents.
Maybe I can create a demo for #SNMP Suite in the future.
But if you need to work with existing agents on the same server, then such flexibility is lost.