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  • Windows Server 2008 - one MAC Address, assign multiple external IP's to VirtualBoxes running as guests on host

    - by Sise
    Couldn't find any help @ google or here. The scenario: Windows Server 2008 Std x64 on i7-975, 12 GB RAM. The server is running in a data centre. One hardware NIC - RealTek PCIe GBE - one MAC Address. The data centre provides us 4 static external IP's. The first is assigned to the host by default of course. I have ordered all 4 IP's, the data centre can assign the available IP's to the physical MAC address of the given NIC only. This means one NIC, one MAC Address, 4 IP's. Everything works fine so far. Now, what I would like to have: Installed VirtualBox with 1-3 guests running, each gets it's own external IP assigned. Each of it should be an standalone Win Server 2008. It looks like the easiest way would be to put the guests into an virtual subnet and routing all data coming to the 2nd till 4th external IP through to this guests using there subnet IP's. I have been through the VirtualBox User Manuel regarding networking. What's not working: I can't use bridged networking without anything else, because the IP's are assigned to the one MAC address only. I can't use NAT networking because it does not allow access from outside or the host to the guest. I do not wanna use port forwarding. Host-only networking itself would not allow internet access, by sharing the default internet connection of the host, internet is granted from the guest to the outside but not from outside or the host to the guest. InternalNetworking is not really an option here. What I have tried is to create an additional MS Loopback adapter for a routed subnet, where the Vbox guests are in, now the idea was to NAT the internet connection to the loopback 'subnet'. But I can't ping the gateway from the guests. By using route command in the command shell or RRAS (static route, NAT) I didn't get there as well. Solutions like the following do work for the one way, but not for the way back: For your situation, it might be best to use the Host-Only adapter for ICS. Go to the preferences of VB itself and select network. There you can change the configuration for the interface. Set the IP address to 192.168.0.1, netmask 255.255.255.0. Disable the DHCP server if it isn't already and that's it. Now the Guest should get an IP from Windows itself and be able to get onto the internet, while you can also access the Host. Slowly I'm pretty stucked with this topic. There is a possibility I've just overlooked something or just didn't getting it by trying, especially using RRAS, but it's kinda hard to find useful howto's or something in the web. Thanks in advance! Best regards, Simon

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  • Reverse DNS for two ADs in the same subnet

    - by SpacemanSpiff
    I currently have two separate AD forests that exist within the same subnet. The two forests have independent copies of the reverse lookup zone for that subnet. Example: Domain A DC1: 10.1.1.1/24 Domain A DC2: 10.1.1.2/24 Domain A AppServer1:10.1.1.3/24 Domain B DC1: 10.1.1.11/24 Domain B DC2: 10.1.1.12/24 Domain B Appserver1:10.1.1.13/24 What I'm after, is a configuration that allows this reverse zone to be shared between them so that both sets of DNS servers can make updates to the zone. This kind of thing is a little far from my everday work, so a kick in the right direction is a welcome suggestion as well. Decoupling one AD into new segments is a possibility I'm open to but would like to avoid if possible. If there is a DNS related solution I'd prefer that.

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  • How to connect two subnet with Windows Server?

    - by 9dan
    Hello, I have some work to do in a small office. This office has two separate Internet connections. One is a kind of DSL line and connected through the Internet sharing router (DHCP). One is a leased line with public IP adresses (No DHCP). This leased line provide only 30 IP addresses and the gateway is provided by the ISP. Some workers use private IP provided by the router, some workers use manually setup public IP. There is a Windows 2008 R2 server with two NICs, connected to each lines. I want to connect/merge(?)/bridge(?) two subnet with this server so that users from the different subnet can access each other. How can I accomplish this? Something like, add gateway function to this server and public IP users change the gateway to point this server.. It it possible ? Sorry for my rambling. Thanks in advance.

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  • VPC SSH port forward into private subnet

    - by CP510
    Ok, so I've been racking my brain for DAYS on this dilema. I have a VPC setup with a public subnet, and a private subnet. The NAT is in place of course. I can connect from SSH into a instance in the public subnet, as well as the NAT. I can even ssh connect to the private instance from the public instance. I changed the SSHD configuration on the private instance to accept both port 22 and an arbitrary port number 1300. That works fine. But I need to set it up so that I can connect to the private instance directly using the 1300 port number, ie. ssh -i keyfile.pem [email protected] -p 1300 and 1.2.3.4 should route it to the internal server 10.10.10.10. Now I heard iptables is the job for this, so I went ahead and researched and played around with some routing with that. These are the rules I have setup on the public instance (not the NAT). I didn't want to use the NAT for this since AWS apperantly pre-configures the NAT instances when you set them up and I heard using iptables can mess that up. *filter :INPUT ACCEPT [129:12186] :FORWARD ACCEPT [0:0] :OUTPUT ACCEPT [84:10472] -A INPUT -i lo -j ACCEPT -A INPUT -i eth0 -p tcp -m state --state NEW -m tcp --dport 1300 -j ACCEPT -A INPUT -d 10.10.10.10/32 -p tcp -m limit --limit 5/min -j LOG --log-prefix "SSH Dropped: " -A FORWARD -d 10.10.10.10/32 -p tcp -m tcp --dport 1300 -j ACCEPT -A OUTPUT -o lo -j ACCEPT COMMIT # Completed on Wed Apr 17 04:19:29 2013 # Generated by iptables-save v1.4.12 on Wed Apr 17 04:19:29 2013 *nat :PREROUTING ACCEPT [2:104] :INPUT ACCEPT [2:104] :OUTPUT ACCEPT [6:681] :POSTROUTING ACCEPT [7:745] -A PREROUTING -i eth0 -p tcp -m tcp --dport 1300 -j DNAT --to-destination 10.10.10.10:1300 -A POSTROUTING -p tcp -m tcp --dport 1300 -j MASQUERADE COMMIT So when I try this from home. It just times out. No connection refused messages or anything. And I can't seem to find any log messages about dropped packets. My security groups and ACL settings allow communications on these ports in both directions in both subnets and on the NAT. I'm at a loss. What am I doing wrong?

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  • Identify malicious subnet

    - by Macros
    I have been experiencing performance issues on a website for a while, and it always seems to hit around the same time. Having analysed the logs I've found a big spike in requests which corresponds with this slowdown, with all requests coming from the same subnet. It feels to me like an attempt to scrape the site (it is a car hire site and the requests are sequential for each IP and with incremental search criteria) and I would like to identify the source. The Subnet in question is 209.67.89.x which I can see is owned by Savvis however I can't reverse DNS any of the IPs - is there any other way I can gain more info on this (other than contacting them direct - I am also doing this)?

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  • How does IPv6 subnetting work and how does it differ from IPv4 subnetting?

    - by Michael Hampton
    This is a Canonical Question about IPv6 Subnetting. Related: How does IPv4 Subnetting Work? I know a lot about IPv4 Subnetting, and as I prepare to (deploy|work on) an IPv6 network I need to know how much of this knowledge is transferable and what I still need to learn. IPv6 seems at first glance to be much more complex than IPv4. So I would like to know: IPv6 is 128 bits, so why is /64 the smallest recommended subnet for hosts? Related to this: Why is it recommended to use /127 for point to point links between routers, and why was it recommended against in the past? Should I change existing router links to use /127? Why would virtual machines be provisioned with subnets smaller than /64? Are there other situations in which I would use a subnet smaller than /64? Can I map directly from IPv4 subnets to IPv6 subnets? My interfaces have several IPv6 addresses. Must the subnet be the same for all of them? Why do I sometimes see a % rather than a / in an IPv6 address and what does it mean? Am I wasting too many subnets? Aren't we just going to run out again? In what other major ways is IPv6 subnetting different from IPv4 subnetting?

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  • PowerConnect 3548p SNTP and web interface not working

    - by Force Flow
    I have been unable to get SNTP and access to the web interface working properly on a Dell PowerConnect 3548p. In the logs, this message appears over and over again: 04-Jan-2000 20:19:29 :%MNGINF-W-ACL: Management ACL drop packet received on interface Vlan 172 from 172.17.0.3 to 172.18.0.10 protocol 17 service Snmp 172 is the management vlan. 172.17.0.3 is the DNS server 172.18.0.10 is the switch's IP address. The DNS server and the switch are located on different subnets and separated by routers. I am unable to access the web interface of the switch from the 172.17.x.x subnet. I can only access the web interface of the switch if I am accessing it from the 172.18.x.x subnet. There is also a managed linksys switch on the 172.18.x.x subnet on the 172 vlan, which has no problem with SNTP. I can also access it from the 172.17.x.x network. So, it stands to reason that this is not a firewall or routing issue, but with the 3548p switch. I suspect the issue is with management permissions/ACLs on the 3348p switch, but that's about as much as I've been able to determine so far. Any ideas?

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  • VPN into multiple LAN Subnets

    - by Rain
    I need to figure out a way to allow access to two LAN subnets on a SonicWall NSA 220 through the built-in SonicWall GlobalVPN server. I've Googled and tried everything I can think of, but nothing has worked. The SonicWall NSA management web interface is also very unorganized; I'm probably missing something simple/obvious. There are two networks, called Network A and Network B for simplicity, with two different subnets. A SonicWall NSA 220 is the router/firewall/DHCP Server for Network A, which is plugged into the X2 port. Some other router is the router/firewall/DHCP server for Network B. Both of these networks need to be managed through a VPN connection. I setup the X3 interface on the SonicWall to have a static IP in the Network B subnet and plugged it in. Network A and Network B should not be able to access each other, which appears the be the default configuration. I then configured and enabled VPN. The SonicWall currently has the X1 interface setup with a subnet of 192.168.1.0/24 with a DHCP Server enabled, although it is not plugged in. When I VPN into the SonicWall, I get an IP address supplied by the DHCP Server on the X1 interface and I can access Network A remotely although I do not have access to Network B. How can I allow access to both Network A and Network B to VPN clients although keep devices on Network B from accessing Network A and vice-versa. Is there some way to create a VPN-only subnet (something like 10.100.0.0/24) on the SonicWall that can access Network A and Network B without changing the current network configuration or allowing devices on both netorks "see" each other? How would I go about setting this up? Diagram of the network: (Hopefully this kind of helps) WAN1 WAN2 | | [ SonicWall NSA 220 ]-(X3)-----------------[ Router 2 ] | | (X2) 192.168.2.0/24 10.1.1.0/24 Any help would be greatly appriciated!

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  • Customer site is out of IP addresses, they want to go from /24 to /12 netmask... Bad idea?

    - by ewwhite
    One of my client sites called to ask me to change the subnet masks of the Linux servers I manage there while they re-IP/change the netmask of their network based on a 10.0.0.x scheme. "Can you change the server netmasks from 255.255.255.0 to 255.240.0.0?" You mean, 255.255.240.0? "No, 255.240.0.0." Are you sure you need that many IP addresses? "Yeah, we never want to run out of IP addresses." A quick check against the Subnet Cheat Sheet shows: a 255.255.255.0 netmask, a /24 provides 256 hosts. It's clear to see that an organization can exhaust that number of IP addresses. a 255.240.0.0 netmask, a /12 provides 1,048,576 hosts. This is a small < 200-user site. I doubt that they'd allocate more than 400 IP addresses. I suggested something that provides fewer hosts, like a /22 or /21 (1024 and 2048 hosts, respectively), but was unable to give a specific reason against using the /12 subnet. Is there anything this customer should be concerned about? Are there any specific reasons they shouldn't use such an incredibly large mask in their environment?

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  • Lock down Wiki access to password only but remain open to a subnet via .htaccess

    - by Treffynnon
    Basically we have a Wiki that has some sensitive information stored in it - not the best I know but my predecessor set it up. I want to be able to request password access from any one who is not on the local network subnet. Those on the local subnet should be able to proceed without entering a password. The following .htaccess does not seem to work any more as it is letting non-local access without requiring the password: AuthName "Our Wiki" AuthType Basic AuthUserFile /path/to/passwd/file AuthGroupFile /dev/null Require valid-user Allow from 192.168 Satisfy Any order deny,allow And I cannot work out why. The WikkaWiki it is supposed to be protecting was recently upgraded, which clobbered the .htaccess file so I restored the above from memory/googling. Maybe I am missing an important directive? The full .htaccess is as follows: AuthName "Our Wiki" AuthType Basic AuthUserFile /path/to/passwd/file AuthGroupFile /dev/null Require valid-user Allow from 192.168 Satisfy Any SetEnvIfNoCase Referer ".*($LIST_OF_ADULT_WORDS).*" BadReferrer order deny,allow deny from env=BadReferrer <IfModule mod_rewrite.c> # turn on rewrite engine RewriteEngine on RewriteBase / # if request is a directory, make sure it ends with a slash RewriteCond %{REQUEST_FILENAME} -d RewriteRule ^(.*/[^/]+)$ $1/ # if not rewritten before, AND requested file is wikka.php # turn request into a query for a default (unspecified) page RewriteCond %{QUERY_STRING} !wakka= RewriteCond %{REQUEST_FILENAME} wikka.php RewriteRule ^(.*)$ wikka.php?wakka= [QSA,L] # if not rewritten before, AND requested file is a page name # turn request into a query for that page name for wikka.php RewriteCond %{QUERY_STRING} !wakka= RewriteRule ^(.*)$ wikka.php?wakka=$1 [QSA,L] </IfModule>

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  • 530 5.7.1 Client was not authenticated Exchange 2010 for some computers within mask

    - by user1636309
    We have a classic problem with Client not Authenticated but with a specific twist: We have an Exchange 2010 cluster, let's say EX01 and EX02, the connection is always to smtp.acme.com, then it is switched through load balancer. We have an application server, call it APP01 There are clients connected to the APP01. There is a need for anonymous mail relay from both clients and APP01. The Anonymous Users setting of the Exchange is DISABLED, but the specific computers - APP01 and clients by the mask, let's say, 192.168.2.* - are enabled. For internal relay, a "Send Connector" is created, and then the above IP addresses are added for the connector to allow computers, servers, or any other device such as a copy machine to use the exchange server to relay email to recipients. The problem is that the relay works for APP01 and some clients, but not others (we get "Client not Authenticated") - all inside the same network and the same mask. This is basically what we do to test it outside of our application: http://smtp25.blogspot.sk/2009/04/530-571-client-was-not-authenticated.html So, I am looking for ideas: What can be the reason for such a strange behaviour? Where I can see the trace of what's going on at the Exchange side?

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  • Windows 2008 R2 Servers Sending Arp Requests for IPs outside Subnet

    - by Kyle Brandt
    By running a packet capture on my my routers I see some of my servers sending ARP requests for IPs that exist outside of its network. For example if my network is: Network: 8.8.8.0/24 Gateway: 8.8.8.1 (MAC: 00:21:9b:aa:aa:aa) Example Server: 8.8.8.20 (MAC: 00:21:9b:bb:bb:bb) By running a capture on the interface that has 8.8.8.1 I see requests like: Sender Mac: 00:21:9b:bb:bb:bb Sender IP: 8.8.8.20 Target MAC: 00:21:9b:aa:aa:aa Target IP: 69.63.181.58 Anyone seen this behavior before? My understanding of ARP is that requests should only go out for IPs within the subnet... Am I confused in my understanding of ARP? If I am not confused, anyone seen this behavior? Also, these seem to happen in bursts and it doesn't happen when I do something like ping an IP outside of the network. Update: In response to Ian's questions. I am not running anything like Hyper-V. I have multiple interfaces but only one is active (Using BACS failover teaming). The subnet mask is 255.255.255.0 (Even if it were something different it wouldn't explain an IP like 69.63.181.58). When I run MS Network Monitor or wireshark I do not see these ARP requests. What happens is that on the router capturing I see a burst of about 10 requests for IPs outside of the network from the host machine. On the machine itself using wireshark or NetMon I see a flood of ARP responses for all the machines on the network. However, I don't see any requests in the capture asking for those responses. So it seems like maybe it is maybe refreshing the arp cache but including IPs that outside of the network. Also when it does this NetMon doesn't show the ARP requests?

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  • Routing subnet over GRE tunnel

    - by eMgz
    Hi, Im trying to configure a GRE over IPSec connection between two subnets. The IPSec tunnel is opened and now I want to add a GRE tunnel over it: ip tunnel add GRE01 mode gre remote 10.244.0.1 local 10.244.245.32 ttl 255 ip link set GRE01 up ip addr add 10.244.248.126 dev GRE01 ip route add 10.244.248.125 dev GRE01 Now I have an interface GRE01 (ifconfig): GRE10 Link encap:UNSPEC HWaddr <h_addr> inet addr:10.244.248.126 P-t-P:10.244.248.126 Mask:255.255.255.255 UP POINTOPOINT RUNNING NOARP MTU:1476 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:0 (0.0 B) TX bytes:0 (0.0 B) And the following routes (ip route list): 10.244.248.125 dev GRE10 scope link <pub_subnet> dev eth0 proto kernel scope link src <pub_ip> default via <pub_gw> dev eth0 metric 100 As a last step, I need now to route my subnet over the tunnel: ip route add 10.245.1.224/28 10.244.248.125 However, I am getting the error Error: either "to" is duplicate, or "10.244.248.125" is a garbage. So, what I didn't understand is why I can't route my subnet over the tunnel, once the only route I have there says that it should route the tunnel IP over the GRE01 interface. Any hint? Thanks.

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  • Isolate clients on same subnet?

    - by stefan.at.wpf
    Given n (e.g. 200) clients in a /24 subnet and the following network structure: client 1 \ . \ . switch -- firewall . / client n / (in words: all clients connected to one switch and the switch connected to the firewall) Now by default, e.g. client 1 and client n can communicate directly using the switch, without any packets ever arriving the firewall. Therefore none of those packets could be filtered. However I would like to filter the packets between the clients, therefore I want to disallow any direct communication between the clients. I know this is possible using vlans, but then - according to my understanding - I would have to put all clients in their own network. However I don't even have that much IP addresses: I have about 200 clients, only a /24 subnet and all clients shall have public ip addresses, therefore I can't just create a private network for each of them (well, maybe using some NAT, but I'd like to avoid that). So, is there any way to tell the switch: Forward all packets to the firewall, don't allow direct communication between clients? Thanks for any hint!

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  • Can't route specific subnet thru VPN in ubuntu

    - by Disco
    I'm having issues routing traffic thru VPN. Here's my setup I have 3 hosts, let's call them A, B and Z B and Z have a VPN connection in the 10.10.10.x SUBNET A and B have a direct connection in the 10.10.12.x SUBNET I want to be able to route traffic from A to Z, like : A <= 10.10.12.254 [LAN] 10.10.12.111 => B <= 10.10.10.152 [VPN] 10.10.10.10 => Z On host B, i have set up ip_forwarding : net.ipv4.ip_forward = 1 and routing on host B: [root@hostA: ~]# ip route 10.10.10.10 dev ppp0 proto kernel scope link src 10.10.10.152 10.10.12.0/24 dev eth1 proto kernel scope link src 10.10.12.111 10.10.10.0/24 dev ppp0 scope link 169.254.0.0/16 dev eth1 scope link routing on host A: [root@hostA: ~]# ip route 10.10.10.0 via 10.10.12.111 dev eth1 10.10.12.0/24 dev eth1 proto kernel scope link src 10.10.12.254 169.254.0.0/16 dev eth1 scope link default via 192.168.1.1 dev eth0 But still not able to ping 10.10.10.10 from host A. Any idea ? I'm pulling my hairs out.

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  • Advertise a subnet route with radvd

    - by Thomas Berger
    we have set up a small IPv6 Testing network. The setup looks like this: ::/0 +----------+ | Firewall | Router to the public net +----------+ | 2001:...::/106 | +----------+ +-------| SIT GW | sit Tunnel gatway to the some test users | +----------+ | +----------+ | Test Sys | Testsystem +----------+ The idea is to advertise the default route from the firewall and the route for the SIT subnets from the sit gateway. The configurations for radvd are: # Firewall interface eth0 { AdvSendAdvert on; route ::/0 { }; }; # SIT Gatway interface eth0 { AdvSendAdvert on; route 2001:...::/106 { }; }; We have captured the adv. packages with tcpdump and the packages looks good. We see a default route from the fw, and the subnet route from the SIT gatway. But if we look on the testsystem there are two default routes over both gateways. There is no subnet route. The routing does not work of course. Here the routes we get: 2001:.....::/64 dev eth0 proto kernel metric 256 mtu 1500 advmss 1440 hoplimit 4294967295 fe80::/64 dev eth0 proto kernel metric 256 mtu 1500 advmss 1440 hoplimit 4294967295 default via fe80::baac:6fff:fe8e:XXXX dev eth0 proto kernel metric 1024 expires 0sec mtu 1500 advmss 1440 hoplimit 64 default via fe80::e415:aeff:fe12:XXXX dev eth0 proto kernel metric 1024 expires 0sec mtu 1500 advmss 1440 hoplimit 64 Any Idea?

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  • Linux NFS create mask and force user equivalent

    - by Mike
    I have two Linux servers: fileserver Debian 5.0.3 (2.6.26-2-686) Samba version 3.4.2 apache Ubuntu 10.04 LTS (2.6.32-23-generic) Apache 2.2.14 I have a number of Samba shares on fileserver so that I can access files from Windows PCs. I am also exporting /data/www-data to the apache server, where I have it mounted as /var/www. The setup is okay, except for when I come to create files on the NFS mount. I end up with files that cannot be read by Apache, or which cannot be modified by other users on my system. With Samba, I can specify force user, force group, create mask and directory mask, and this ensures that all files are created with suitable permissions for my Apache web server. I can't find a way to do this with NFS. Is there a way to force permissions and ownership with NFS - am I missing something obvious? Although I've spent quite a bit of time with Linux, and am weaning myself off Windows, I still haven't quite got to grip with Linux permissions... If this is not the right way to do things, I am open to alternative suggestions.

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  • Sending eMails in a external subnet in vmware ESXi

    - by user80658
    This might be a bit hard for me to explain - and it is a pretty individual situation. I got a native server at Hetzner (www.hetzner.de). The public IP is 88.[...].12. I got ESXi running on this server. I can access the esxi console by the public ip, but none of the virtual machines. That's why I bought a public subnet with 8 (6 usable) IPs (46.[...]) and an additional public ip (88.[...].26). This additional public ip belongs to the first virtual maschine - a firewall appliance - which is connected to the WAN. This need to be done this way - since it is the official way by hetzner. My 46. subnet is behind the firewall. I got a virtualmin server with dovecot imap/pop3 server. When sending a email, most provider (gmail) will accept those mails, but a lot will put it into spam (aol). My theory is: The MX line of my domain says of course the ip of the virtual machine (46.[...]), but in the raw email it says that email is sent by the ip of the firewall (88.[...].26), which doesnt sound trustworthy. A solution would be if the firewall could handle mail, but it simply cant. How can I prevent this problem? Thanks.

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  • Private subnet for VM server host-only network

    - by Derek Pressnall
    At my current job, we distribute a product based on a Linux server with multiple VMs defined (using KVM / libvirt). We are planning to expose limited ports to the customer's network, and use iptables to direct inbound traffic to the appropriate internal VM. My question: is there a class of private subnets that I can use for the internal host-only network that is least likely to conflict with a client IP subnet? Specifically, if I choose a /24 out of any of the RFC-1918 defined private subnets (such as 192.168.x.x), there is a chance of conflicting with a customer-used range. I noticed that several current VM implementations default to 192.168.122.x -- is this due to an RFC that I'm not familiar with, and therefore this is a safe range to use (that most network admins would avoid)? Or did the various VM vendors just pick that range randomly? I guess I'm looking for an IP range that is more private than the existing private (RFC1918) addresses. The only other thought I had was to use one of the "Test Net" IP ranges reserved for documentation purposes (RFC 5737). Note, that I'm not worried about a customer's network blocking these IPs, as this is only internal to our server (packets get NATted before leaving the box). However this does seem more unorthodox than just sticking with the default 192.168.122.x/24 subnet.

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  • Two network interfaces and two IP addresses on the same subnet in Linux

    - by Scott Duckworth
    I recently ran into a situation where I needed two IP addresses on the same subnet assigned to one Linux host so that we could run two SSL/TLS sites. My first approach was to use IP aliasing, e.g. using eth0:0, eth0:1, etc, but our network admins have some fairly strict settings in place for security that squashed this idea: They use DHCP snooping and normally don't allow static IP addresses. Static addressing is accomplished by using static DHCP entries, so the same MAC address always gets the same IP assignment. This feature can be disabled per switchport if you ask and you have a reason for it (thankfully I have a good relationship with the network guys and this isn't hard to do). With the DHCP snooping disabled on the switchport, they had to put in a rule on the switch that said MAC address X is allowed to have IP address Y. Unfortunately this had the side effect of also saying that MAC address X is ONLY allowed to have IP address Y. IP aliasing required that MAC address X was assigned two IP addresses, so this didn't work. There may have been a way around these issues on the switch configuration, but in an attempt to preserve good relations with the network admins I tried to find another way. Having two network interfaces seemed like the next logical step. Thankfully this Linux system is a virtual machine, so I was able to easily add a second network interface (without rebooting, I might add - pretty cool). A few keystrokes later I had two network interfaces up and running and both pulled IP addresses from DHCP. But then the problem came in: the network admins could see (on the switch) the ARP entry for both interfaces, but only the first network interface that I brought up would respond to pings or any sort of TCP or UDP traffic. After lots of digging and poking, here's what I came up with. It seems to work, but it also seems to be a lot of work for something that seems like it should be simple. Any alternate ideas out there? Step 1: Enable ARP filtering on all interfaces: # sysctl -w net.ipv4.conf.all.arp_filter=1 # echo "net.ipv4.conf.all.arp_filter = 1" >> /etc/sysctl.conf From the file networking/ip-sysctl.txt in the Linux kernel docs: arp_filter - BOOLEAN 1 - Allows you to have multiple network interfaces on the same subnet, and have the ARPs for each interface be answered based on whether or not the kernel would route a packet from the ARP'd IP out that interface (therefore you must use source based routing for this to work). In other words it allows control of which cards (usually 1) will respond to an arp request. 0 - (default) The kernel can respond to arp requests with addresses from other interfaces. This may seem wrong but it usually makes sense, because it increases the chance of successful communication. IP addresses are owned by the complete host on Linux, not by particular interfaces. Only for more complex setups like load- balancing, does this behaviour cause problems. arp_filter for the interface will be enabled if at least one of conf/{all,interface}/arp_filter is set to TRUE, it will be disabled otherwise Step 2: Implement source-based routing I basically just followed directions from http://lartc.org/howto/lartc.rpdb.multiple-links.html, although that page was written with a different goal in mind (dealing with two ISPs). Assume that the subnet is 10.0.0.0/24, the gateway is 10.0.0.1, the IP address for eth0 is 10.0.0.100, and the IP address for eth1 is 10.0.0.101. Define two new routing tables named eth0 and eth1 in /etc/iproute2/rt_tables: ... top of file omitted ... 1 eth0 2 eth1 Define the routes for these two tables: # ip route add default via 10.0.0.1 table eth0 # ip route add default via 10.0.0.1 table eth1 # ip route add 10.0.0.0/24 dev eth0 src 10.0.0.100 table eth0 # ip route add 10.0.0.0/24 dev eth1 src 10.0.0.101 table eth1 Define the rules for when to use the new routing tables: # ip rule add from 10.0.0.100 table eth0 # ip rule add from 10.0.0.101 table eth1 The main routing table was already taken care of by DHCP (and it's not even clear that its strictly necessary in this case), but it basically equates to this: # ip route add default via 10.0.0.1 dev eth0 # ip route add 130.127.48.0/23 dev eth0 src 10.0.0.100 # ip route add 130.127.48.0/23 dev eth1 src 10.0.0.101 And voila! Everything seems to work just fine. Sending pings to both IP addresses works fine. Sending pings from this system to other systems and forcing the ping to use a specific interface works fine (ping -I eth0 10.0.0.1, ping -I eth1 10.0.0.1). And most importantly, all TCP and UDP traffic to/from either IP address works as expected. So again, my question is: is there a better way to do this? This seems like a lot of work for a seemingly simple problem.

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  • How to genrate a monochrome bit mask for a 32bit bitmap

    - by Mordachai
    Under Win32, it is a common technique to generate a monochrome bitmask from a bitmap for transparency use by doing the following: SetBkColor(hdcSource, clrTransparency); VERIFY(BitBlt(hdcMask, 0, 0, bm.bmWidth, bm.bmHeight, hdcSource, 0, 0, SRCCOPY)); This assumes that hdcSource is a memory DC holding the source image, and hdcMask is a memory DC holding a monochrome bitmap of the same size (so both are 32x32, but the source is 4 bit color, while the target is 1bit monochrome). However, this seems to fail for me when the source is 32 bit color + alpha. Instead of getting a monochrome bitmap in hdcMask, I get a mask that is all black. No bits get set to white (1). Whereas this works for the 4bit color source. My search-foo is failing, as I cannot seem to find any references to this particular problem. I have isolated that this is indeed the issue in my code: i.e. if I use a source bitmap that is 16 color (4bit), it works; if I use a 32 bit image, it produces the all-black mask. Is there an alternate method I should be using in the case of 32 bit color images? Is there an issue with the alpha channel that overrides the normal behavior of the above technique? Thanks for any help you may have to offer! ADDENDUM: I am still unable to find a technique that creates a valid monochrome bitmap for my GDI+ produced source bitmap. I have somewhat alleviated my particular issue by simply not generating a monochrome bitmask at all, and instead I'm using TransparentBlt(), which seems to get it right (but I don't know what they're doing internally that's any different that allows them to correctly mask the image). It might be useful to have a really good, working function: HBITMAP CreateTransparencyMask(HDC hdc, HBITMAP hSource, COLORREF crTransparency); Where it always creates a valid transparency mask, regardless of the color depth of hSource. Ideas?

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  • Bonjour/mDNS Broadcast across subnets

    - by Matthew Savage
    I have just setup a new OSX Server in our office and verified that everything is working fine over our wired network (192.168.126.0/24). The problem that I am having is that our clients (Mac Laptops) are mainly connected via Wireless, which are running on a different subnet (192.168.1.0/24), and the mDNS Broadcast isn't reaching this subnet. The network configuration is somewhat foreign to myself (I don't manage the network in this location, but as of just recently the servers), however I don't believe there is any firewalls or routing rules between the two subnets which might cause the traffic to be rejected. I'm wondering if this is simply the mDNS broadcast not able to broadcast over the two different subnets (I'm still reading up on broadcast to understand it more) or there is something else which I might be able to try.

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  • Adding IP address to OpenVZ VPS (OpenVZ Web Panel)

    - by andy
    I apologise if I sound at all dumb. This is my first dedicated server having used a VPS for over a year and I'm trying to setup a VPS on this new server. I purchased a subnet from my hosting provider that I believe allows me 6 usable IP addresses: 177.xx.xxx.201 - 177.xx.xxx.206 The subnet address looks like this: 177.xx.xxx.200/29. I've gone on my server and added them like it said on a wiki like so: ip addr add 177.**.***.201/29 dev eth0 I done that for all six and now when I go to them in the browser they point to my server. The problem is, I'm using OpenVZ web panel to create VMs (http://code.google.com/p/ovz-web-panel/) so I created a VM and assigned one of those IPs to it. However when SSHing to that IP it SSH's to the dedicated server and not the VM. Am I missing something?

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  • Sonicwall site-to-site can not access remote network

    - by vpnwizard
    I have 2 SonicWall devices (tz100) in 2 different geographical locations. They are connected to each other using site-to-site vpn connection and this works just great. Device A network - 192.168.1.0/24 Device B network - 192.168.2.0/24 When I connect to one device, I can access, from my computer, anything on that specific subnet. However, I am unable to view anything, from my computer, on the other network. Is there a setting somewhere that will forward my requests to the other subnet? Example - I VPN into Device A, but would like to get to a server which is on the Device B network (192.168.2.0/24)

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