network profile
| bio | website | |
|---|---|---|
| location | ||
| age | ||
| visits | member for | 1 year, 4 months |
| seen | Feb 28 at 4:02 | |
| stats | profile views | 9 |
linux, python, floss, trading
|
Feb 21 |
awarded | Citizen Patrol |
|
Feb 21 |
comment |
When would I open Port 53 for DNS? Gentlemen, this argument via comments is pointless. Michael Hampton, indeed, but the practice of allowing client/server communication via the same privileged port (0-1023) has been stopped by Iana RFCs. @Shane I am not talking about theoretical possibilities, but practical reality: the OP is "Locking down an application server" and has tagged it "linux". If you want to disprove my assertion then prove it wrong via a source or command line output. I have work to do and will not engage in further talk. |
|
Feb 21 |
comment |
When would I open Port 53 for DNS? Condescension doesn't change the fact that the OP is referring to a Linux host. A note on your answer doesn't change the fact that the TCP/IP model (of which UDP is a subset) does not allow common services (like DNS) to communicate over the same port. Your answer statement "You need to have UDP 53 allowed for responses to DNS queries that your server sends, as UDP is a stateless protocol. Don't block it if you want any kind of outbound connectivity, software updates, etc." is wrong. |
|
Feb 21 |
comment |
When would I open Port 53 for DNS? Look man, you're talking a lot but the answer to the question remains that you only need port 53 open on a host that serves DNS to the network. Execute 'tcpdump -n -s 1500 -i eth0 udp port 53' to confirm that a client DNS request never uses port 53 on the localhost |
|
Feb 21 |
awarded | Critic |
|
Feb 21 |
comment |
When would I open Port 53 for DNS? i politely but totally disagree with the stated need for port 53 to be open to external hosts in order for the localhost to resolve DNS. I am writing this message from a machine with port 53 closed. TCP connection tracking on the (localhost) firewall manages the authenticity of DNS queries going out from random ports above port 1023. |
|
Feb 21 |
revised |
When would I open Port 53 for DNS? tcpdump code |
|
Feb 21 |
comment |
When would I open Port 53 for DNS? the belief that outbound DNS queries use port 53 is incorrect. |
|
Feb 21 |
answered | When would I open Port 53 for DNS? |
|
Dec 31 |
answered | Where to see logs of a program that crashes on Ubuntu Server? |
|
Dec 27 |
awarded | Supporter |
|
Dec 26 |
answered | Restrict User Access to Certain Ports |
|
Dec 25 |
awarded | Editor |
|
Dec 25 |
revised |
Firewalling tool for VirtualBox formatting to emphasize critical terms |
|
Dec 25 |
awarded | Teacher |
|
Dec 25 |
answered | Firewalling tool for VirtualBox |
