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Can a port be TCP and UDP?
2 Answers. Yes, you can use the same port number for both TCP and UDP. Many protocols already do this, for example DNS works on udp/53 and tcp/53.
What ports do TCP and UDP use?
Table 1 Common TCP/IP Protocols and Ports
| Protocol | TCP/UDP | Port Number |
|---|---|---|
| Domain Name System (DNS) (RFC 1034-1035) | TCP/UDP | 53 |
| Dynamic Host Configuration Protocol (DHCP) (RFC 2131) | UDP | 67/68 |
| Trivial File Transfer Protocol (TFTP) (RFC 1350) | UDP | 69 |
| Hypertext Transfer Protocol (HTTP) (RFC 2616) | TCP | 80 |
Why does NAPT translate both IPv4 and UDP ports?
NAPT translates both the IPv4 address and the transport address (TCP port, UDP port, or ICMP identifier). The reason is that there may be multiple hosts using the NAT which could be using the same protocol with the same transport address (port or identifier). There are different types of NAT.
Why does Nat translate to a source port?
First, assume your NAT host only has one IP address (N) to translate to. Second, assume you actually have an extra coincidence where internal hosts A and B both try to communicate with external host X on port 80 with source port 17835. A’s packets (when generated, before NAT) look like: src: A:17835, dst: X:80.
What to do if Nat is not working on your router?
If you are positive you do not own a router or a broadband modem with NAT features, please skip down to the Software Firewall section. Ensure you are using a port number that is not already reserved by a computer process or PC on your network, or that is possibly being blacklisted/throttled by your ISP.
What does it mean when a server is out of ports?
Having huge connections in TIME_WAIT state does not always indicate that the server is currently out of ports unless the first two points are verified. Having lot of TIME_WAIT connections does indicate that the process is creating lot of TCP connections and may eventually lead to port exhaustion.