I am exercising Linux timestamping functionality (TX part): https://docs.kernel.org/networking/timestamping.html It looks like there is no easy way to understand that the system will never provide me with TX timestamps at runtime. It means that I can enable TX timestamping via setsockopt without an error: eve…
Tag: networking
How does the host name resolution of anyname.localhost resolves to IPv6 ::1 address?
In an Ubuntu 20 or 22 LTS, if I attempt to use a hostname like anyname.localhost it always seems to resolve to IPv6 ::1 address. In an old RHEL 6, if I attempt to use a hostname like anyname.localhost it always seems to resolve to IPv4 127.0.0.1 address. In a MS-Windows or MacOS 12.6 machine, this does not se…
How to monitor all network traffic from a specific process in linux?
I want to monitor and log all traffic that a specific process produces. I know about tcpdump, but it seems it doesn’t support filtering by process (pid/path, or at least user). It there any other way to log all traffic from a process? Ideally I should be able to filter ports as well. Thanks! Answer You …
linux + formula to convert IPV6 address to IP address
Formula to convert IPv6 Address to IP address number I’m looking for a formula to convert IPV6 address to IP address . for example – lets say we have the ipv6 as the following Input IPV6 address : 2001:0db8:0000:0000:0000:ff00:0042:8329 Output IP Number converted : 32.136.7.34 Answer to IP address…
When using recv(n), with n greather than the MTU are you guaranteed to read at least a whole layer 2 frame?
I was wondering, imagine if there is no data to read from a TCP socket, then a whole frame of 1492 bytes arrives (full). In your code (C or any language supporting TCP) you have let’s say recv 4096 bytes, will the OS guarantee that the recv reads the whole 1492 bytes, or is it possible that the loading …
How to get all ip ranges from asn?
I want to get all IP address ranges/blocks from as number. I can search throw google but need to write them manually. I want to get them all at once? Is this possible to get only ip address ranges from websites at once? Answer You can use whois servers instead of bgp.he.net or any other websites like this. wh…
How to check if the IP address that a socket is bound to is still one of the valid machine’s addresses?
Once I call socket(); bind() (with a specific IP address, not INADDR_ANY); listen(), there seems to be no way of determining if the IP address is still a valid address of one of the system’s interfaces. What I looked into using: Checking error with getsockopt(SO_ERROR); Using epoll()-ing on some EPOLLER…
AWK to print subnet 0.69.100.in-abc.def
My requirement is to print a subnet 100.69.0.0/10 value to 0.69.100.in-abc.def. I tried as below but i got output like this How to get output using awk as below Answer Good attempt and you were close, try following. With OP’s approach we need to put [ and ] as field separator too, so that we could catch…
How to open port 80 for node server on local machine?
How can I use the port 80 on my local Linux machine as the port of my node server? The netstat command netstat -ptuln says the following about this port, while the node server is running: I found on this site some recommendations for the command sudo iptables -I INPUT -p tcp -m tcp –dport 80 -j ACCEPT. …
blocking all internal traffic except incoming traffic from a specific ip on a single port
I’m trying to use IPtables to block all internal traffic with the exception of one server, here are my rules but when i telnet from another instance i can still connect…. Answer When debugging iptables I normally: reset all the counter – ‘iptables -Z’ make the connection then rev…