Tag Info

New answers tagged

3

If you reject the packet, you reply to the incoming SYN with a RST packet, so the scanner knows the port is closed (via reject, or because no service is running on that port). If you drop the packets, the scanner waits, and after some time (timeout), it assumes the packets have been dropped (although, they may be lost in transit, or the machine on the far ...


1

The pipe value in the output of ping indicates the maximum number of unanswered ICMP echo request packets outstanding in the network at some point during the test. It is not normally reported when this value is one (every request received a response before the next request was sent), which is the case under normal operation. By default, the ping command ...


0

In short: The “pipe” number is the maximum number of echo request packets that have been under way at one time, without having been answered by an echo reply packet (but did get answered in the end). A detailed answer can be found at the source for this quote, at ...


1

Install VirtualBox (or some other virtualization provider) Install pfSense within a VirtualBox machine Configure whatever network topology/routing you want to test Profit! :) Is still iptables the right tool for the job? Would it be possible to do what I want? With a linux system, iptables would be part of the solution, yes, but if you're asking ...


4

The entry in /etc/sysconfig/network is where RHEL (and derivatives such as CentOS) set the hostname/nodename that you'll see reflected on for instance the prompt of your shell, in system and log messages etc. That is the hostname that will be returned by the gethostname(2) and uname system calls. A system only has one hostname/nodename, but it can have ...


0

This problem doesn't occur on X11VNC, I have switched VNC servers on one of the computers and the problem did not reoccur.


0

I believe that I've found the solution, being a developer and not a sys admin, this took a little time to figure out but ultimately, I believe that the issue was that for transparent proxying to work, the proxy needs to also be the target host's default gateway. That way: The proxy makes a spoofed call, impersonating the original client The target host ...


0

You can do this with multiple listen directives Listen 192.0.2.1:80 Listen 203.0.113.1:80 Multiple Listen directives may be used to specify a number of addresses and ports to listen to. The server will respond to requests from any of the listed addresses and ports. On a CentOS System I have to hand Listen 192.168.254.16:80 netstat -tnlp | ...


4

It's all DNS resolution. If the DNS server is slow, it delays netstat. Pass -n to netstat when you invoke it to skip resolution and it'll often return immediately. The other cause of the delay is if you use the -p (-b in Windows) to return the process owner since some processes don't like to be queried if you're not root/Administrator.


1

In general, you could find this out using a tool such as strace: sudo strace -e trace=file -f -s128 lshw -class network


0

You can check the interface capacity in following ways. dmesg | grep eth0 mii-tool -v eth0 ethtool eth0 Note:- Change the device name according to yours.


3

You're looking in the wrong place. Look at /sys/class/net/<device>/speed.


0

It is possible to place part of the process tree in a separate network namespace through the use of CLONE_NEWNET. Each namespace work as an independent network stack. Each network interface can be used in just one namespace at a time. Packets between the network namespaces can be send using virtual network interfaces. I can't tell from your question, if ...


1

A quick glance at the iptables man page show support for an owner module for setting up rules based on user and/or group ID's. It only works for locally generated packets (i.e. not on the router managing traffic from different workstations). Then a policy based routing setup comes to mind, combining to something like: iptables -A OUTPUT -o owner ...


1

According to user ID seems a bit difficult (are they connecting to your server via SSH, or just using it as a router?), you could quite easily do it by IP or MAC address, if you have control of your network.


1

You should be able to remove the relevant entries from the /etc/network/interfaces file but check out it's associated documentation interfaces(5) to be sure.


2

Honestly, the right thing to do is to pick the ISP where you put your main mail server a little more carefully. But assuming that's out of the question, I wouldn't do this at layer 3 (iptables), I'd do it at layer 4 (application, being SMTP), taking advantage of SMTP's inherent store-and-forward nature. The procedure looks somewhat like this: Set up a ...


1

Yes this seems reasonable. You should set the firewall policy to be deny and then only open the ports that you require.


2

There's actually a bug in mtr for report mode that mis counts the last packet. It's fixed in a newer version (mtr v0.80) See: https://bugs.launchpad.net/ubuntu/+source/mtr/+bug/966065 https://bugzilla.redhat.com/show_bug.cgi?id=611739


-1

Additional cents for presenting this rule from being re- generated in a batch. Usually I use this at our DevOps practice for i in `cat /tmp/allnode.lst | awk '{print $1}'`; do echo $i; \ ssh $i 'mv /lib/udev/rules.d/75-persistent-net-generator.rules /tmp/'; done Col 1 in allnode.lst is IP address


3

When your virtual machines use in-host virtual networking (they only communicate with the host or other VMs running under the same host) you can assign literally any IP address you want. But when you would like to communicate with VMs or bare-metal machines running on other servers, you will need to use the network infrastructure of your hosting provider, ...


5

You can use any addresses in the following ranges: 10.x.x.x 192.168.x.x 172.16.x.x - 172.31.x.x As mentioned by others, your provider may have certain ranges or addresses reserved. If that is the case, they would probably let you know, since it would be completely irresponsible not to do so (you could break their network otherwise). See this wiki ...


8

You can use any private addresses you want, that's kind of their definition. (That said, there are cases like running private networks inside a provider where they may need to set up or give you the private addresses for internal routing/switching reasons)


6

Are you willing to accept working DNS a point of failure in your environment or not. Some services/applications will fail in certain configurations if a system cannot resolve the local machine's name. If you have an absolutely critical service that must be running in all situations, it isn't unusual to add a an entry in the hosts file so that service can ...



Top 50 recent answers are included