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  • Blocked connections passing through firewall. What is wrong?

    - by Kiranu
    In our company we have a small business router (Cisco RV082) on which we are using its standard configuration (block all incoming traffic). We also have an SMTP relay configured (using WS2008R2) so that our internal applications can send email through google apps (which requires authentication). The thing is that the server was being used to send spam. We fixed the problem by only allowing the server to relay email from our internal IP address range (10.0.0.0/16). My concern is that there was a way by which external IPs connected to the network and that underlying problem has not been fixed, but I cannot imagine how these machines connected. Any thoughts?

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  • Is there anything that can be done to make X forwarding over LAN less painful?

    - by Earlz
    I have two *nix machines that I like to remotely do graphical things sometimes with. One of those machines is my Arch Linux media server, and another is my OpenBSD router/general server. My current task was installing a Windows XP over virtual box on my media server. I preferred to do the installation from my main workstation so that I could continue to watch TV from my media server on it's "actual" display. I soon noticed that X forwarding is quite painful though, even over low-latency LAN connections. Are there any settings I can tweak to make it a bit less painfully slow, jittery, and laggy? My LAN is rather small, 100Mbit, and ping times to the other box average at about 0.15ms. Also, I know Virtualbox has a VNC mode it can use instead of doing X forwarding, but this particular task was just an example

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  • How to use Public IP in case of two ISP when two differs from each other

    - by user1471995
    Please bare with my long explanation but this is important to explain the actual problem. Please also pardon my knowledge with PFsense as i am new to this. I have single PFSense box with 3 Ethernet adapter. Before moving to configuration for these, i want to let you know i have two Ethernet based Internet Leased Line Connectivity let's call them ISP A and ISP B. Then last inetrface is LAN which is connected to network switch. Typical network diagram ISP A ----- PFSense ----> Switch ---- > Servers ISP B ----- ISP A (Initially Purchased) WAN IP:- 113.193.X.X /29 Gateway IP :- 113.193.X.A and other 4 usable public IP in same subnet(So the gateway for those IP are also same). ISP B (Recently Purchased) WAN IP:- 115.115.X.X /30 Gateway IP :- 115.115.X.B and other 5 usable public IP in different subnet(So the gateway for those IP is different), for example if 115.119.X.X2 is one of the IP from that list then the gateway for this IP is 115.119.X.X1. Configuration for 3 Interfaces Interface : WAN Network Port : nfe0 Type : Static IP Address : 113.193.X.X /29 Gateway : 113.193.X.A Interface : LAN Network Port : vr0 Type : Static IP Address : 192.168.1.1 /24 Gateway : None Interface : RELWAN Network Port : rl0 Type : Static IP Address : 115.115.X.X /30 (I am not sure of the subnet) Gateway : 115.115.X.B To use Public IP from ISP A i have done following steps a) Created Virtual IP using either ARP or IP Alias. b) Using Firewall: NAT: Port Forward i have created specific natting from one public IP to my internal Lan private IP for example :- WAN TCP/UDP * * 113.193.X.X1 53 (DNS) 192.168.1.5 53 (DNS) WAN TCP/UDP * * 113.193.X.X1 80 (HTTP) 192.168.1.5 80 (HTTP) WAN TCP * * 113.193.X.X2 80 (HTTP) 192.168.1.7 80 (HTTP) etc., c) Current state for Firewall: NAT: Outbound is Manual and whatever default rule are defined for the WAN those are only present. d) If this section in relevant then for Firewall: Rules at WAN tab then following default rule has been generated. * RFC 1918 networks * * * * * Block private networks * Reserved/not assigned by IANA * * * * * * To use Public IP from ISP B i have done following steps a) Created Virtual IP using either ARP or IP Alias. b) Using Firewall: NAT: Port Forward i have created specific natting from one public IP to my internal Lan private IP for example :- RELWAN TCP/UDP * * 115.119.116.X.X1 80 (HTTP) 192.168.1.11 80 (HTTP) c) Current state for Firewall: NAT: Outbound is Manual and whatever default rule are defined for the RELWAN those are only present. d) If this section in relevant then for Firewall: Rules at RELWAN tab then following default rule has been generated. * RFC 1918 networks * * * * * * Reserved/not assigned by IANA * * * * * * Last thing before my actual query is to make you aware that to have multiple Wan setup i have done following steps a) Under System: Gateways at Groups Tab i have created new group as following MultipleGateway WANGW, RELWAN Tier 2,Tier 1 Multiple Gateway Test b) Then Under Firewall: Rules at LAN tab i have created a rule for internal traffic as follows * LAN net * * * MultipleGateway none c) This setup works if unplug first ISP traffic start routing using ISP 2 and vice-versa. Now my main query and problem is i am not able to use public IP address allocated by ISP B, i have tried many small tweaks but not successful in anyone. The notable difference between the two ISP is a) In case of ISP A there Public usable IP address are on same subnet so the gateway used for the WAN ip is same for the other public IP address. b) In case of ISP B there public usable IP address are on different subnet so the obvious the gateway IP for them is different from WAN gateway's IP. Please let me know how to use ISP B public usable IP address, in future also i am going to rely for more IPs from ISP B only.

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  • TCP video streaming: TCP throughput(rate) and RTT

    - by misteryes
    we know that a rough estimation of TCP rate is: WINDOW/RTT, where WINDOW is the min(CWIN, RWIN), CWIN is the congestion window size of the sender, while RWIN is the receiving window. nowadays, the encoding rate of videos may be 1000KB/s(8000kbit/s), if RTT is 500ms, it needs the window size to be 2000KB. But we know that usually the receiving window size is below 64KB, there is a big gap. so if RTT is too large, TCP streaming is not possible? Is my understanding right? thanks!

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  • how do i automatically add a new route to the routing table?

    - by Robbie Mckennie
    I'm looking at linking two networks with a long range Ethernet bridge. I know I can connect my two networks with a router, but my problem is how will my computers know where to send packets if I don't add the route manually? I COULD add them manually, but it seems like a hassle. I have very very limited knowledge of RIP (I know it has something to do with routing), but I don't know how to use it. edit: My vision for the network would be the 2 networks (which are currently independent home networks), connected by a microwave Ethernet link. I assumed i'd need a router on one end of the bridge, to handle communication between the 2 networks.

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  • iptables question

    - by RubyFreak
    i have a small network, with one valid IP and a firewall with 3 network interfaces (LAN, WAN, DMZ). I want to enable PAT on this valid IP to redirect http traffic to a server in my DMZ. (done) I want to enable MASQ on this ip from traffic that comes from my LAN (done) I want from my LAN as well to access my http server at DMZ. (partially) Question: in the above scenario, i cannot from my LAN, to access my http server in the DMZ, since it has the IP used by the MASQ (the only valid ip that i have). What would be the best option to solve this problem? network interfaces: eth0 (WAN) eth1 (DMZ) eth2 (LAN) /sbin/iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE /sbin/iptables -A FORWARD --o eth1 -d 2.2.2.2 -p tcp --dport 80 -j ACCEPT /sbin/iptables -t nat -A PREROUTING -i eth0 -d 1.1.1.1 -p tcp --dport 80 -j DNAT --to 2.2.2.2 /sbin/iptables -A FORWARD -i eth0 -o eth1 -m state --state RELATED,ESTABLISHED -j ACCEPT /sbin/iptables -A FORWARD -i eth1 -o eth0 -j ACCEPT /sbin/iptables -A FORWARD -i eth2 -o eth0 -j ACCEPT

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  • bridge to share WiFi internet connection over eth0

    - by rubo77
    In this script there is implemented that you create a mesh network and connect other machines to your device to serve an internet connection with dhcp: echo "starting bridge to share internet connection over eth0" ifconfig eth0 up promisc brctl addbr br-freifunk brctl addif br-freifunk bat0 brctl addif br-freifunk eth0 echo "internet starting, this may take some minutes due to latency..." echo "(use" echo "tail -f /var/log/syslog" echo "in another window for debugging)" echo echo dhclient br-freifunk echo "The error 'Rather than invoking init scripts through /etc/init.d...' can be ignored:" dhclient br-freifunk # without bridge: dhclient bat0 This works fine with the freifunk-mesh network. But how can I serve internet in a normal case? I would like to connect to any open Wifi I find with my network-manager or wicd (yes, with the graphical GUI) and then start a small script that creates a bridge to my network-out on my laptop I use Ubuntu and my networkcards are eth0 and wlan0

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  • how're routing tables populated?

    - by Robbie Mckennie
    i've been reading "tcp/ip illustrated" and i started reading about ip forwarding. all about how you can receive a datagram and work out where to send it next based on the desination ip and your routing table. but what confused me is how (in a home network setting) the table itself is populated. is there a lower layer protocol at work here? does it come along with dhcp? or is it simply based on the ip address and netmask of each interface? i do know (from other books) that in the early days of ethernet one had to set up routing tables by hand, but i know i didn't do that.

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  • Trouble Connecting to Virtual Machine after IP address Change

    - by David
    I have a VMware image running a copy of Fedora 11 which is hosted on a remote server. The remote server recently had its IP address change. I'm now unable to connect to my virtual machine. The server admin assures me that my virtual machine is running and assigned the new IP address. I have checked the firewalls and had the remote admin restart the VM instance. Neither of these fixed the problem. How do I troubleshoot a remote server which I am unable to SSH to? I'm actually even unable to ping the remote IP (connection timed out).

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  • ipv6 with KVM on debian

    - by Eliasdx
    I have trouble setting up IPV6 on my Proxmox (KVM) server: My ISP sent me this information(xxx=placeholder): IPs: 2a01:XXX:XXX:301:: /64 Gateway: 2a01:XXX:XXX:300::1 /59 This is the interface setup on the host server: auto vmbr1 iface vmbr1 inet static address 178.XX.XX.4 broadcast 178.XX.XX.63 netmask 255.255.255.192 pointopoint 178.XX.XX.1 gateway 178.XX.XX.1 bridge_ports eth0 bridge_stp off bridge_fd 0 iface vmbr1 inet6 static address 2a01:XXX:XXX:301::2 netmask 64 up ip -6 route add 2a01:XXX:XXX:300::1 dev vmbr1 down ip -6 route del 2a01:XXX:XXX:300::1 dev vmbr1 up ip -6 route add default via 2a01:XXX:XXX:300::1 dev vmbr1 down ip -6 route del default via 2a01:XXX:XXX:300::1 dev vmbr1 On the guest: auto eth0 iface eth0 inet static address 178.xx.xx.47 netmask 255.255.255.255 broadcast 178.xx.xx.63 gateway 178.xx.xx.1 pointopoint 178.xx.xx.1 iface eth0 inet6 static pre-up modprobe ipv6 address 2a01:XXX:XXX:301::2:2 netmask 64 up ip -6 route add 2a01:XXX:XXX:300::1 dev eth0 down ip -6 route del 2a01:XXX:XXX:300::1 dev eth0 up ip -6 route add default via 2a01:XXX:XXX:300::1 dev eth0 down ip -6 route del default via 2a01:XXX:XXX:300::1 dev eth0 Ipv4 works on both host and guest but Ipv6 only works "sometimes". It's up for minutes and then down again until I change something. However I can actually ping the host and the guest from both host and guest. host:~# ip -6 neigh 2a01:XXX:XXX:301::100:2 dev vmbr1 lladdr 00:50:56:00:00:e0 REACHABLE 2a01:XXX:XXX:300::1 dev vmbr1 lladdr 00:26:88:76:18:18 router STALE host:~# ip -6 route 2a01:XXX:XXX:300::1 dev vmbr1 metric 1024 mtu 1500 advmss 1440 hoplimit 4294967295 2a01:XXX:XXX:301::/64 dev vmbr1 proto kernel metric 256 mtu 1500 advmss 1440 hoplimit 4294967295 fe80::/64 dev vmbr0 proto kernel metric 256 mtu 1500 advmss 1440 hoplimit 4294967295 fe80::/64 dev eth0 proto kernel metric 256 mtu 1500 advmss 1440 hoplimit 4294967295 fe80::/64 dev vmbr1 proto kernel metric 256 mtu 1500 advmss 1440 hoplimit 4294967295 fe80::/64 dev tap101i1d0 proto kernel metric 256 mtu 1500 advmss 1440 hoplimit 4294967295 default via 2a01:XXX:XXX:300::1 dev vmbr1 metric 1024 mtu 1500 advmss 1440 hoplimit 4294967295 Does someone know why it isn't working? And is there a way to configure multiple v6 IPs from the same subnet so I can dedicate IPs to websites on a server with multiple virtualhosts?

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  • Linux/hostapd: AP can ping clients, clients can access internet, can't access www@wlan1 with more than 5-6 packets at once

    - by mhambra
    Please edit the title, can't make it sound better. -- OP. Hi all, I have a Wifi USB dongle in a PC, that serves as an AP for laptop. wlan1: 192.168.2.1, netmask 255.255.255.0, routed: route add -net 192.168.2.0 netmask 255.255.255.0 gw 192.168.2.1 ping 192.168.2.2 (laptop): ping was ok for lot of packets. Now, I try to access 192.168.2.1:80/myindex.html (apache) from laptop, and can see that own 1kb test page. But, trying to access 192.168.2.1:80/my.jpg, I see the following: GET /my.jpg HTTP/1.1 200 OK <jpg header, about a kilobyte> <TCP packet retransmisson> <TCP packet retransmisson> <end of stream> It seems to be a hostapd's problem (networked stuff worked fine with Ad-Hoc), but it may be also forwarding/routing problem too. What to google for? Even more strange, SSH to that host works fine.

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  • I need a reverse proxy solution for SSH

    - by Bond
    Hi here is a situation I have a server in a corporate data center for a project. I have an SSH access to this machine at port 22.There are some virtual machines running on this server and then at the back of every thing many other Operating systems are working. Now Since I am behind the data centers firewall my supervisor asked me if I can do some thing by which I can give many people on Internet access to these virtual machines directly. I know if I were allowed to get traffic on port other than 22 then I can do a port forwarding. But since I am not allowed this so what can be a solution in this case. The people who would like to connect might be complete idiots.Who may be happy just by opening putty at their machines or may be even filezilla.I have configured an Apache Reverse Proxy for redirecting the Internet traffic to the virtual machines on these hosts.But I am not clear as for SSH what can I do.So is there some thing equivalent to an Apache Reverse Proxy which can do similar work for SSH in this situation. I do not have firewall in my hands or any port other than 22 open and in fact even if I request they wont allow to open.2 times SSH is not some thing that my supervisor wants.

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  • Why does my Mac address reset after reconnecting?

    - by Mr.Student
    I have ubuntu 12. I'm changing my mac address with ifconfig wlan0 hw ether xx:xx:xx:xx:xx:xx which works. However when I restart my connection my computer resets my mac to my original mac address. I'm guessing that this happens because something calls... ifconfig wlan0 down ... do something before connecting ifconfig wlan0 up ... connect to designated access point I want my mac address to however be the same no matter how many times I disconnect and reconnect, whether to another network or the same one. Also it would be nice to turn off the auto-connect feature for my network-manager with out having to edit each individual connection. Lastly I would like to know how to connect to a wifi network through the terminal and not via gui network manager ubuntu provides.

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  • Dynamic DNS on D-Link DWR-112 3G router uses a private IP address

    - by user270151
    I'm using a D-Link DWR-112 3G router to connect to the internet by using Celcom broadband plug-in. How can I do the port forwarding to my server? I already have correctly configured my DynDNS, but every time the DynDNS will not set to public address but local private address with in the range 10.xxx.xxx.xxx. My router address is 192.168.1.1 and server address is 192.168.1.5. Can someone give me some guideline about this issue?

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  • if an outdated, vulnerable but clean Windows machine is connected to network behind router, can it be detected and attacked?

    - by EndangeringSpecies
    suppose the machine is clean of all malware but not in any sense updated, patched, secured etc. Suppose I connect it to the internet from behind wireless router with the intent of using it only on a few trusted sites and only there. Or, for the sake of argument, maybe I wouldn't do any browsing at all, just let it sit there connected to the network. This is all happening in a residential situation with cable internet. In this situation can a remote attacker somehow detect the fact that the machine is connected to the internet and try connecting to do an exploit?

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  • Choosing a home network layout

    - by James M.
    I have a server, 4 PC's, a network printer, a switch and an ADSL modem. Currently the server runs Red Hat 9 and sits between the internet and the other PCs like in http://upload.wikimedia.org/wikipedia/en/1/12/Sample-network-diagram.png I have bought a new server PC to replace the old one, and I plan to install Fedora Core linux on it. The server acts as web and file server. The PCs all run Windows. Alternatively, I could connect the new server and all PCs to the switch, and connect the switch to the modem. (Sorry, couldn't find an image.) What are the pros and cons of these network layouts? Eg. in terms of reliability, security and flexibility? I am not a Linux guru but know of (and am not afraid of) iptables, dhcpd et al. Thank you for any tips, pointers and links.

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  • How to create a separated network to customers only?

    - by Valter Henrique
    I work in a company where we have a network ethernet and wi-fi, we would like to create a network where our customers could access our network but don't have access to our computer network. This access would be internet only, nothing more. The customers will not see our computers and the files that we share in our network. I have two routers, how can I do this ? A Cisco Linksys Wireless-N Broadband Router WRT160N V3 and a Netgear Wireless G Router WGR614 v9 and about firewalls there´s only windows firewalls in each computer by default.

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  • Why is my ethernet interface in promiscuous mode

    - by nhed
    I read that seeing a flag of M in netstat -i is the way to tell which of your interfaces is in promiscuous mode I run it and I see that eth1 is in promiscuous mode $ netstat -i Kernel Interface table Iface MTU Met RX-OK RX-ERR RX-DRP RX-OVR TX-OK TX-ERR TX-DRP TX-OVR Flg eth1 1500 0 1770161198 0 0 0 57446481 0 0 0 BMRU lo 16436 0 97501566 0 0 0 97501566 0 0 0 LRU This seems to be the case on all the machines I checked (All Centos6.0, both virtual and physical), any idea why ethernet devices would be in such a mode unless someone was running any pcap based app (sudo lsof | grep pcap shows nothing)? I did not see any mention of promiscuous in any of the config files (sudo grep -r promis /etc) Any ideas what puts the interface into that mode and why? p.s. most of the posts I see seem to be security related, this is not that

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  • Copying between 2 network devices

    - by Dave Rook
    My network has 3 devices - 1 PC and 2 other network devices (which could be PC, NAS, external hard drive etc) If I want to copy data from one network device to another network device from my PC (using the copy and paste method (i.e right click a file, select copy and then right click into the destination folder and click paste) and therefore not using any tools that could be built into the network devices for such a transaction), does the data get routed via my PC or use my systems resources?

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  • Flow of packet in network

    - by user58859
    I can't visualize in my mind the network traffic flow. eg. If there are 15 pc's in a LAN. When packet goes from router to local LAN, do it passes all the computers? Means did it goes to ehernet card of every computer and those computers accept the packet based on their physical address. To which pc the packet will go first? To the nearest to the router? What happen if that first pc captures that packet(though it is not for it)? What happens when a pc broadcast a message? Do it have to generate 14 packets for all the pc's or only one packet reach to all pc's? If it is one packet and captured by first pc, how other pc's can get that? I can't imagine how this traffic is exactly flows? May be my analogy is completely wrong. Can anybody explain me this? Thanks in advance.

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  • VM can't connect to outside in bridged mode

    - by Kamal
    Hi Guys, I am not able to ping any machine(not even the host) from Guest VM in bridged mode. But I got an IP which is on the same subnet as host. I can ping my guest VM from the host and can use ssh to connect to the guest. I am using Vmware workstation 6.5. Guest VM is a centos VM and host is windows xp. Every thing works fine in NAT mode. Any clues as to what could be happening. I tried disabling all the firewalls I have.

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  • Moving files from Public folder to C: takes a minute, even though they are same hard drive and same

    - by Jian Lin
    I have a big file, like 2GB, and would like to move it from Network -> Bookroom -> Users -> Public (this is the computer in the bookroom in the house) to c:\myfiles and they are actually on the SAME hard drive (and same partition). But copying still takes a minute or so? I thought if on the same hard drive and partition, then it is a "move" and it should take 2, 3 seconds only. that public folder also is \\Bookroom\Users\Public Update: Sorry, I actually mean "move" all the way... so it is not copy but move. So that's why I thought it should take 2, 3 seconds only.

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  • Configure Wireless Network Card

    - by Skizz
    I recently upgraded the wireless network card in my Ubuntu PC from an 802.11g to an 802.11n. Now, it can't see my router. It doesn't appear in the list of networks that is displayed when you click on the NetworkManager icon in Gnome. Other networks are listed and I have connected to them (no password required!). I'm using the Windows driver through ndiswrapper and it can see the card. I tested the card in a Windows PC and everything worked. The router's log doesn't show any messages coming from the wireless card. What have I done wrong? If you need any more information, just leave a comment and I'll get add it to the question.

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  • How do I set up a bridge on Ubuntu GNOME 14.04

    - by NJRandy
    I found a guide for setting up a bridge in Fedora and was trying this: $ nmcli connection delete p33p1 $ nmcli connection add con-name br0 type bridge ifname br0 autoconnect yes $ nmcli connection add con-name p33p1 type bridge-slave ifname p33p1 master br0 autoconnect yes I found that $ nmcli con delete uuid [uuid here] accomplished the first step. nmcli connection does not have an 'add' action in this distribution. Please help me do the 2nd and 3rd steps. Context: I am trying to set up a virtual machine. I believe this is a necessary step for the VM to access my network and the internet. Please feel free to correct me if I am wrong! BTW, I am a linux newbie, tech oldie. Thank you.

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