@Javier No it doesn't. Opening a port from the point of view of the server application occurs when you bind the listening socket, or rather bind the socket you are about to listen() on. More probably the question is about opening it in the firewall. Far too many errors here, and all uncorrected in 7 years.
A TCP/IP network connection may be either blocked, dropped, open, or filtered. These actions are generally controlled by the IPtables firewall the system uses and is independent of any process or program that may be listening on a network port. On macOS, here's an easy way to get the process ID that's listening on a specific port with netstat. This example looks for a process serving content on port 80: find server running on port 80 netstat -anv | egrep -w [.]80.*LISTEN sample output tcp4 0 0 *.80 *.* LISTEN 131072 131072 715 0 The 2nd from the last column is the PID. Jul 13, 2005 · The domain name service provided by BIND (named) software. It uses both UDP and TCP protocol and listen on port 53. DNS queries less than 512 bytes are transferred using UDP protocol and large queries are handled by TCP protocol such as zone transfer. ADVERTISEMENTS i) named/bind server â€“ TCP/UDP port 53 ii)Client (browser, dig … Continue reading "Linux Iptables block or open DNS To specify which interface to listen on: tcpdump -i eth1. To specify which IP address to listen for (will listen to both source and destination): tcpdump host 10.64.45.53. To specify a port that is either source or destination: tcpdump port 8080. To specify a source port use: tcpdump src port 8443. To specify a destination port use: tcpdump dst Port(s) FortiManager v3.0: FortiGuard Web Filtering and Antispam rating replies: Source: UDP 53 (default) or UDP 8888 Destination: UDP 1027 or UDP 1031: FortiOS v3.0: FortiGuard Web Filtering and Antispam rating lookup This can be to the FDN or to a FortiManager acting as a private FDS. Source: UDP 1027 or 1031 Destination: UDP 53 (default) or
If our port analysis reveals that your system's port 53 is open and listening for incoming traffic, you should determine what's going on. Even though only a few Trojan programs are known to open port 53, the exact behavior of malicious software is a constantly moving target . . . which is why periodic security checkups here are always worthwhile.
TCPDump port, host, and interface - TunnelsUP To specify which interface to listen on: tcpdump -i eth1. To specify which IP address to listen for (will listen to both source and destination): tcpdump host 10.64.45.53. To specify a port that is either source or destination: tcpdump port 8080. To specify a source port use: tcpdump src port 8443. To specify a destination port use: tcpdump dst Linux Iptables block or open DNS / bind service port 53
Allow Both TCP and UDP Port 53 to Your DNS Servers
The problem is that my university campus doesn't allow connections to go outside when the port is different than TCP port 22, 80, 443, or UDP port 123. I tested them manually. On my Debian server I would like to listen to all my UDP and TCP ports so I can clearly figure out which TCP and UDP ports my university let through their firewall. How to Check Service Running on Specific Port on Linux Jul 04, 2018