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14

You have the symptoms of an MTU problem: some TCP connections freeze, more or less reproducibly for a given command or URL but with no easily discernible overall pattern. A telltale symptom is that interactive ssh sessions work well but file transfers almost always fail. Furthermore pppoe is the number one bringer of MTU problem for home users. So I ...


12

IP Network Troubleshooting There are a few standard things you can look for when you are experiencing network connectivity issues. These are listed here from a top-down, or least fundamental to most fundamental issues. All the example ip commands shown here use a Linux-specific tool called iproute2. Many of the tasks can likely be done with ifconfig and ...


10

check iftop and nload iftop does for network usage what top(1) does for CPU usage. It listens to network traffic on a named interface and displays a table of current bandwidth usage by pairs of hosts. Handy for answering the question "why is our ADSL link so slow?". nload is a console application which monitors network traffic and bandwidth usage ...


8

Maybe setup smokeping on the Linux side, and point it at your AP? Smokeping will periodically (configurable) send -20 pings at the same time, and then graph how how many returned and the range of times that they returned in. If you have a lot of dropped packets, or the really wide range, then you should be concerned. If you want to run smokeping you ...


7

Deleting the default route should do this. You can show the routing table with /sbin/route, and delete the default with: sudo /sbin/route del default That'll leave your system connected to the local net, but with no idea where to send packets destined for beyond. This probably simulates the "no external access" situation very accurately. You can put it ...


7

In a terminal: steam --reset This will provide a clean install for the client, but leave all your games untouched. Be aware that although this will "fix" your connection issue, it's akin to buying a new car to fix a flat tire. There is probably a simpler and more elegant solution, but I wasn't able to find one when I had this problem.


6

I'd highly recommend you use RSA keys rather than passwords for remote SSH logons. Second, you'll want to install Fail2Ban or something similar to discourage brute force breakin attempts (although again, disabling password authentication in favor of RSA public/private key authentication for SSH access would make this a mostly moot point) Third, it's ...


6

You can get somewhat close by querying the public whois database. It'll likely be somewhat difficult to "productify" to handle every possible case, but a reasonable approximation might be: $ whois a.b.c.d | grep -iE ^country: where a.b.c.d is the IP address in question. whois is often installed by default, so this meets a reasonable interpretation of ...


5

This is definitely feasible. Many of us were running mixed, load-balanced broadband configs for corporate years ago and they worked really well. Many probably still do! You can do it in a number of ways, including using iptables rules and/or iproute2 (ip(8) command) to setup policy routing. The load balancing is not done at the packet level, but at the ...


5

You could use Linux containers to create an environment with no network interfaces. For example, if I create a configuration file like this: # lxc.network.type = empty And then start a shell like this: # lxc-execute --name bash -f /tmp/lxc.conf /bin/bash I will find that within this shell there are no network devices available other than lo: # ...


5

Spoofing your MAC-Address is relatively simple: General steps: Save your MAC for a future reset Temporary disable your interface to change your MAC Set your new, arbirtray MAC Enable your interface again Using different tools: With ip: ip link show <interface> &> ip_savehafen.log sudo ip link set dev <interface> down sudo ip ...


4

So, basically your Linux box acts as a firewall? First, enable IP forwarding. echo 1 > /proc/sys/net/ipv4/ip_forward echo 1 > /proc/sys/net/ipv4/conf/all/forwarding Then, add some forwarding rules: iptables -A FORWARD -i eth0 -j ACCEPT iptables -A FORWARD -m state --state ESTABLISHED,RELATED -j ACCEPT Secure the FORWARD chain: iptables -P ...


4

You can use iftop to show bandwidth usage.


4

You wrote So, how do I simulate "no external access" in my development machine? How do I "deactivate" my ethernet interface and reactivate later with no hassle? Are these two questions or one question? I'm not sure what you mean by simulate "no external access". However, to deactivate the ethernet interface you could simply do #ifdown eth0 ...


4

Make sure you keep your SSH server up-to-date. OpenSSH has a good security record, but you don't want to. Consider carefully whether you need to allow password authentication. Normally you should be logging in only from trusted computers (don't type a password on a computer that may be running a key logger), and these trusted computers are generally under ...


4

They're in the $http_proxy, $https_proxy and $ftp_proxy environment variables. Also, $no_proxy contains a comma-separated list of host patterns for which no proxy is used. For example: http_proxy=http://proxy.example.com:3128/ no_proxy=localhost,127.0.0.1,*.example.com


4

Is there a chance that your IP is duplicated on the network? Given that you have done all of this testing the next step would be to use an intermediate hop in between and go to the website from your computer. Use a free proxy online. There are several available. I have seen this issue before and it turned out that the IP was being blacklisted blackholed by ...


4

You can share the internet by configuring the Cent OS server as a NAT machine and giving private ip addresses to the LAN machines. As in your case, the USB wireless interface is ppp0 and the LAN interface is eth0 on the Cent OS server. Step-1: Providing private ip addresses to LAN interface on Cent OS and to the other machines in the LAN. You can give any ...


4

Masquerading: All machines in your internal network appear at the same (set of) public addresses. I.e., you can have 8 public IP addresses, and a network of 200 machines with private addresses using them to go "outside". When a host inside wants to open a connection to the outside, the connection gets assigned an ID address and port from this pool. It was ...


4

Use another IP locator than ifconfig.me that provides with that information like: curl -s 'http://geoiplookup.net/geoapi.php?output=countrycode' or: curl -s 'http://geoiplookup.net/geoapi.php?output=country' (see the API for details) or: curl -s http://whatismycountry.com/ | sed -n 's|.*,\(.*\)</h1>|\1|p' or: curl -s ...


4

Installing Archlinux as a Guest on Virtualbox March 15, 2013 11:54 pm Essentially, you can follow this guide, but there are several additional steps to take. https://wiki.archlinux.org/index.php/Beginners’_Guide#Installation To fix the network: /usr/sbin/dhcpd enp0s3 to check that you can load the dhcp client. ln -s ...


4

Let's call the machine that has internet access hasinet and the one that doesn't noinet. If you can make an SSH connection from noinet to hasinet You can do this easily with OpenSSH's built-in SOCKS proxy. This command will set up a SOCKS proxy on noinet listening on port 1080: noinet$ ssh -D 1080 hasinet If you can only make SSH connections to noinet ...


4

If you just see Loopback interface with ifconfig command Then issue ifconfig -a This will list all of your adapters on VM OS. Lets assume that you have eth0 as your primary adapter, then simply write following command: ifup eth0 After interface goes up, you'll be able to see it listed in ifconfig output and you should be able to ping outside world.


3

In OpenBSD you set up networking by creating a file called /etc/hostname.iwn0 (or whatever else your interface is called). Thus you should probably just add the following to your /etc/hostname.iwn0: dhcp nwid [network name] wpa wpapsk [password]


3

You could use ping, netstat or traceroute. You'll find a small introduction here.


3

echo 1 > /proc/sys/net/ipv4/ip_forward or edit /etc/sysctl.conf and set 1 to the net.ipv4.ip_forward (It should be net.ipv4.ip_forward=1). This will make that change persistant after a reboot. iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE (or you can save it in rc.local file) eth0 - replace with your Dell Wifi port connect the two ...


3

There are three parts in your question, in fact: Decide on a blocking strategy at the network level: what connections are allowed? Implement that blocking strategy. … in a way that only affects certain users. Blocking websites is not easy. In fact, I would say that it's impossible to completely block a website without completely blocking network access. ...


3

One of the easier ways would be to run the WINE program as a different user and set up netfilter to drop packets from that user. Eg, where "wineusername" is your Wine user and em1 is your network interface: iptables -A OUTPUT -o em1 -m owner --uid-owner wineusername -j DROP iptables -A FORWARD -o em1 -m owner --uid-owner wineusername -j DROP iptables -A ...


3

Simple Here's a very simple iptables ruleset that masquerades everything. This one works for many simpler setups. It won't work if the box is working as a full-blown router — it has a potentially nasty habit of NATting all traffic that leaves your computer. iptables -A POSTROUTING -o eth+ -t nat -j MASQUERADE iptables -A POSTROUTING -o wlan+ -t nat -j ...


3

You could try flushing out your DNS. You could set your DNS to 8.8.8.8 (google public DNS server). You might also clear out your arp cache. for arptable in `arp | grep "eth1" | cut -d " " -f1`; do arp -d $arptable; done



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