topic Do we need to open DNS port for internal DNS servers? in Network Security https://community.cisco.com/t5/network-security/do-we-need-to-open-dns-port-for-internal-dns-servers/m-p/969903#M939185 <P>We recently replace our checkpoint to cisco ASA. In our old firewall every tcp/udp ports outbound are blocked, ofcourse except for port 443 and 80. With the ASA we just started blocking all the ports outbound and I noticed that our DNS servers keeps on reaching different outside IP's on port 53 and not sure if I supposed to allow this or block it. If I block it, we might have problems with our DNS. Should I allow all our internal DNS server to any udp/tcp ports outbound? Thank you in advance. </P> Mon, 11 Mar 2019 12:32:08 GMT bauti1428 2019-03-11T12:32:08Z Do we need to open DNS port for internal DNS servers? https://community.cisco.com/t5/network-security/do-we-need-to-open-dns-port-for-internal-dns-servers/m-p/969903#M939185 <P>We recently replace our checkpoint to cisco ASA. In our old firewall every tcp/udp ports outbound are blocked, ofcourse except for port 443 and 80. With the ASA we just started blocking all the ports outbound and I noticed that our DNS servers keeps on reaching different outside IP's on port 53 and not sure if I supposed to allow this or block it. If I block it, we might have problems with our DNS. Should I allow all our internal DNS server to any udp/tcp ports outbound? Thank you in advance. </P> Mon, 11 Mar 2019 12:32:08 GMT https://community.cisco.com/t5/network-security/do-we-need-to-open-dns-port-for-internal-dns-servers/m-p/969903#M939185 bauti1428 2019-03-11T12:32:08Z Re: Do we need to open DNS port for internal DNS servers? https://community.cisco.com/t5/network-security/do-we-need-to-open-dns-port-for-internal-dns-servers/m-p/969904#M939189 <HTML><HEAD></HEAD><BODY><P>You will need to allow your internal dns server to make dns requests outbound. udp 53</P></BODY></HTML> Wed, 16 Apr 2008 15:39:52 GMT https://community.cisco.com/t5/network-security/do-we-need-to-open-dns-port-for-internal-dns-servers/m-p/969904#M939189 acomiskey 2008-04-16T15:39:52Z Re: Do we need to open DNS port for internal DNS servers? https://community.cisco.com/t5/network-security/do-we-need-to-open-dns-port-for-internal-dns-servers/m-p/969905#M939193 <HTML><HEAD></HEAD><BODY><P>I tried just the udn 53 but still getting a lot of blocks from port 53. I opened UDP/TCP dns and it stop the logs. What about port 137 outbound? </P></BODY></HTML> Wed, 16 Apr 2008 15:50:03 GMT https://community.cisco.com/t5/network-security/do-we-need-to-open-dns-port-for-internal-dns-servers/m-p/969905#M939193 bauti1428 2008-04-16T15:50:03Z Re: Do we need to open DNS port for internal DNS servers? https://community.cisco.com/t5/network-security/do-we-need-to-open-dns-port-for-internal-dns-servers/m-p/969906#M939198 <HTML><HEAD></HEAD><BODY><P>for DNS server you need to open both tcp and udp 53 for your server .</P><P>port 137 is for netbios , and it is local .</P></BODY></HTML> Mon, 21 Apr 2008 05:18:30 GMT https://community.cisco.com/t5/network-security/do-we-need-to-open-dns-port-for-internal-dns-servers/m-p/969906#M939198 Nasser Heidari 2008-04-21T05:18:30Z