Problem solved: $ ssh -L 7000:127.0.0.1:7000 user@host -N -v -v …apparently, ‘localhost‘ was not liked by the remote host. Yet, remote /etc/hosts contains: ::1 localhost localhost. 127.0.0.1 localhost localhost. while the local network interface is lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 33184 inet 127.0.0.1 netmask 0xff000000 inet6 ::1 prefixlen 128 inet6 fe80::1%lo0 prefixlen 64 scopeid 0x2 Sigh. so … Read more
These are dynamically configured link-local addresses. They are only valid on a single network segment and are not to be routed. Of particular note, 169.254.169.254 is used in AWS, Azure and other cloud computing platforms to host instance metadata service.
It depends on the subnet of the IP address in question. In general, the first and last addresses in a subnet are used as the network identifier and broadcast address, respectively. All other addresses in the subnet can be assigned to hosts on that subnet. For example, IP addresses of networks with subnet masks of … Read more
One simple method is to simply run a sniffer like tcpdump/wireshark on a computer and send out a DHCP request. If you see any offers other then from your real DHCP server then you know you have a problem.
Speed of Light: You are not going beat the speed of light as an interesting academic point. This link works out Stanford to Boston at ~40ms best possible time. When this person did the calculation he decided the internet operates at about “within a factor of two of the speed of light”, so there is … Read more
Since you are on a Windows machine, these things can be done: Execute the following command and look for a “:3306” listener (you did not mention UDP/TCP). This will confirm there is something running on the port. netstat -a -n After this, if you are expecting incoming connections on this port and feel that the … Read more
First and foremost, there is nothing to fear from being on a public IP allocation, so long as your security devices are configured right. What should I be replacing NAT with, if we don’t have physically separate networks? The same thing we’ve been physically separating them with since the 1980’s, routers and firewalls. The one … Read more
Actually there is a way to kill a connection – killcx. They claim it works in any state of the connection (which I have not verified). You need to know the interface where communication happens though, it seems to assume eth0 by default. UPDATE: another solution is cutter which comes in some linux distros’ repositories.
There is a “secret” keyboard shortcut to force an exit :~) From the frozen session, hit these keys in order: Enter~. The tilde (only after a newline) is recognized as an escape sequence by the ssh client, and the period tells the client to terminate it’s business without further ado. The long-hang behavior on communication … Read more
The first thing that should be mentioned about IPv6 subnetting is that a different mode of thought is called for. In IPv4 you usually think about how many addresses you have available and how you can allocate enough of them to each end user. In IPv6 you usually think about how many /64–subnets you have … Read more