Re: [courier-users] monitoring prgram times out
On 03/26/2017 09:44 AM, SZÉPE Viktor wrote: Running bind is too expensive for me. I'll note that Red Hat's bind package installs with an ideal configuration for a localhost-only caching DNS server. There's virtually no administrative cost, there. I usually use the caching DNS resolver in the given datacenter plus µnscd https://busybox.net/~vda/unscd/ which does local caching for Name Service - which Courier apparently is not using. Nope. nscd (and unscd) are not DNS servers, they're caches for the libc nss functions (gethostbyaddr, etc) that aren't used in Courier. -- Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot___ courier-users mailing list courier-users@lists.sourceforge.net Unsubscribe: https://lists.sourceforge.net/lists/listinfo/courier-users
Re: [courier-users] monitoring prgram times out
Idézem/Quoting Matus UHLAR - fantomas: >>> On 26.03.17 18:44, SZÉPE Viktor wrote: Running bind is too expensive for me. > >> Idézem/Quoting Matus UHLAR - fantomas : >>> are you trying to say that it's more expensive than running courier mail >>> server? > > On 29.03.17 13:30, SZÉPE Viktor wrote: >> I'd like to use the DNS resolver from the given datacenter. >> Optimizing and maintaining (thus learning) another linux daemon is >> what really is expensive. > > 1. as I stated, the server should be able to resolve localhost > > 2. if you do any kind of spam detection (blacklist), using others' name > server could result to worse spam detection. Thank you. Most of my Courier installs are satellite servers sending message through one transactional provider like Amazon SES, Mailjet, Mandrill or Sendgrid as I am not able to maintain more than 1 full featured mail server. My mail server with mailboxes has a dedicated resolver server with "unbound". SZÉPE Viktor https://github.com/szepeviktor/debian-server-tools/blob/master/CV.md -- +36-20-4242498 s...@szepe.net skype: szepe.viktor Budapest, III. kerület -- Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot ___ courier-users mailing list courier-users@lists.sourceforge.net Unsubscribe: https://lists.sourceforge.net/lists/listinfo/courier-users
Re: [courier-users] monitoring prgram times out
>> On 26.03.17 18:44, SZÉPE Viktor wrote: >>> Running bind is too expensive for me. >Idézem/Quoting Matus UHLAR - fantomas: >> are you trying to say that it's more expensive than running courier mail >> server? On 29.03.17 13:30, SZÉPE Viktor wrote: >I'd like to use the DNS resolver from the given datacenter. >Optimizing and maintaining (thus learning) another linux daemon is >what really is expensive. 1. as I stated, the server should be able to resolve localhost 2. if you do any kind of spam detection (blacklist), using others' name server could result to worse spam detection. -- Matus UHLAR - fantomas, uh...@fantomas.sk ; http://www.fantomas.sk/ Warning: I wish NOT to receive e-mail advertising to this address. Varovanie: na tuto adresu chcem NEDOSTAVAT akukolvek reklamnu postu. They that can give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety. -- Benjamin Franklin, 1759 -- Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot ___ courier-users mailing list courier-users@lists.sourceforge.net Unsubscribe: https://lists.sourceforge.net/lists/listinfo/courier-users
Re: [courier-users] monitoring prgram times out
Idézem/Quoting Matus UHLAR - fantomas: > On 26.03.17 18:44, SZÉPE Viktor wrote: >> Running bind is too expensive for me. > > are you trying to say that it's more expensive than running courier mail > server? Hello Matus! I'd like to use the DNS resolver from the given datacenter. Optimizing and maintaining (thus learning) another linux daemon is what really is expensive. SZÉPE Viktor https://github.com/szepeviktor/debian-server-tools/blob/master/CV.md -- +36-20-4242498 s...@szepe.net skype: szepe.viktor Budapest, III. kerület -- Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot ___ courier-users mailing list courier-users@lists.sourceforge.net Unsubscribe: https://lists.sourceforge.net/lists/listinfo/courier-users
Re: [courier-users] monitoring prgram times out
On 26.03.17 18:44, SZÉPE Viktor wrote: >Running bind is too expensive for me. are you trying to say that it's more expensive than running courier mail server? -- Matus UHLAR - fantomas, uh...@fantomas.sk ; http://www.fantomas.sk/ Warning: I wish NOT to receive e-mail advertising to this address. Varovanie: na tuto adresu chcem NEDOSTAVAT akukolvek reklamnu postu. How does cat play with mouse? cat /dev/mouse -- Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot ___ courier-users mailing list courier-users@lists.sourceforge.net Unsubscribe: https://lists.sourceforge.net/lists/listinfo/courier-users
Re: [courier-users] monitoring prgram times out
>SZÉPE Viktor writes: >>2) Is it possible for Courier to skip DNS lookups for "localhost"? >> >>I wonder why Courier is not using gethostbyname(). >>/etc/hosts contains: >>127.0.0.1 localhost.localdomain localhost all recursive DNS servers should have localhost defined. Also, mailservers should use own recursive DNS servers, topologically close, so resolving localhost should not be a problem. On 26.03.17 10:32, Sam Varshavchik wrote: >gethostbyname/gethostbyaddr can only look up A addresses. Courier >needs MX records, and so needs to use its own resolver; and with its >own DNS resolver code already in place, it makes no sense to use >different resolvers. Note that different MTAs do the same. AFAIK neither sendmail nor postfix support gethostbyname() or anything other to look up /etc/hosts. -- Matus UHLAR - fantomas, uh...@fantomas.sk ; http://www.fantomas.sk/ Warning: I wish NOT to receive e-mail advertising to this address. Varovanie: na tuto adresu chcem NEDOSTAVAT akukolvek reklamnu postu. There's a long-standing bug relating to the x86 architecture that allows you to install Windows. -- Matthew D. Fuller -- Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot ___ courier-users mailing list courier-users@lists.sourceforge.net Unsubscribe: https://lists.sourceforge.net/lists/listinfo/courier-users
Re: [courier-users] monitoring prgram times out
SZÉPE Viktor writes: Thank you again! Running bind is too expensive for me. I usually use the caching DNS resolver in the given datacenter plus µnscd https://busybox.net/~vda/unscd/ which does local caching for Name Service - which Courier apparently is not using. >if (nodnslookup || getenv("NODNSLOOKUP")) return; Is there a non-zero chance to get this into the next release? Yes; I just have to test this myself. pgpcC5hXxdUNt.pgp Description: PGP signature -- Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot___ courier-users mailing list courier-users@lists.sourceforge.net Unsubscribe: https://lists.sourceforge.net/lists/listinfo/courier-users
Re: [courier-users] monitoring prgram times out
Idézem/Quoting Sam Varshavchik: > SZÉPE Viktor writes: > >> Thank you for your support! >> >> -nodnslookup is the solution for satellite type server which delivery >> messages through one smarthost. >> >> What should I do on normal (tcp/25,587,465 are open to the internet) >> mail server where DNS lookup is necessary? Is there a way to exclude >> localhost from DNS lookup on the initial (pre-EHLO) connection? > > Looking at the code there does not appear to be a way to select > -nodnslookup based on the connecting IP address. > > There is a facility for selectively setting environment variables > based on the connecting IP address, the smtpaccess list (see > makesmttpaccess). But, currently nodnslookup just looks only at the > parameter. > > In tcpd.c, you can try changing > >if (nodnslookup) return; > > to something like > >if (nodnslookup || getenv("NODNSLOOKUP")) return; > > and then put > > 127.0.0.1allow,NODNSLOOKUP=1 > > into the smtpaccess file. > > But why don't you just run bind locally, and have it handle DNS > resolution for local zones. You can have it listen only on local IP > addresses, and thusly inaccessible from the Internet, and then get > some benefits of a local DNS lookup cache. Thank you again! Running bind is too expensive for me. I usually use the caching DNS resolver in the given datacenter plus µnscd https://busybox.net/~vda/unscd/ which does local caching for Name Service - which Courier apparently is not using. >if (nodnslookup || getenv("NODNSLOOKUP")) return; Is there a non-zero chance to get this into the next release? SZÉPE Viktor https://github.com/szepeviktor/debian-server-tools/blob/master/CV.md -- +36-20-4242498 s...@szepe.net skype: szepe.viktor Budapest, III. kerület -- Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot ___ courier-users mailing list courier-users@lists.sourceforge.net Unsubscribe: https://lists.sourceforge.net/lists/listinfo/courier-users
Re: [courier-users] monitoring prgram times out
SZÉPE Viktor writes: Thank you for your support! -nodnslookup is the solution for satellite type server which delivery messages through one smarthost. What should I do on normal (tcp/25,587,465 are open to the internet) mail server where DNS lookup is necessary? Is there a way to exclude localhost from DNS lookup on the initial (pre-EHLO) connection? Looking at the code there does not appear to be a way to select -nodnslookup based on the connecting IP address. There is a facility for selectively setting environment variables based on the connecting IP address, the smtpaccess list (see makesmttpaccess). But, currently nodnslookup just looks only at the parameter. In tcpd.c, you can try changing if (nodnslookup) return; to something like if (nodnslookup || getenv("NODNSLOOKUP")) return; and then put 127.0.0.1allow,NODNSLOOKUP=1 into the smtpaccess file. But why don't you just run bind locally, and have it handle DNS resolution for local zones. You can have it listen only on local IP addresses, and thusly inaccessible from the Internet, and then get some benefits of a local DNS lookup cache. pgpczm2zko9wi.pgp Description: PGP signature -- Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot___ courier-users mailing list courier-users@lists.sourceforge.net Unsubscribe: https://lists.sourceforge.net/lists/listinfo/courier-users
Re: [courier-users] monitoring prgram times out
Idézem/Quoting Sam Varshavchik: > SZÉPE Viktor writes: > > >> 2) Is it possible for Courier to skip DNS lookups for "localhost"? >> >> I wonder why Courier is not using gethostbyname(). >> /etc/hosts contains: >> 127.0.0.1 localhost.localdomain localhost > > gethostbyname/gethostbyaddr can only look up A addresses. Courier > needs MX records, and so needs to use its own resolver; and with its > own DNS resolver code already in place, it makes no sense to use > different resolvers. > > There are several options in the esmtpd config file that control DNS > lookups on incoming connections: > > BOFHCHECKDNS; and TCPDOPTS passes through the options to > couriertcpd, such as -nodnslookup. Thank you for your support! -nodnslookup is the solution for satellite type server which delivery messages through one smarthost. What should I do on normal (tcp/25,587,465 are open to the internet) mail server where DNS lookup is necessary? Is there a way to exclude localhost from DNS lookup on the initial (pre-EHLO) connection? SZÉPE Viktor https://github.com/szepeviktor/debian-server-tools/blob/master/CV.md -- +36-20-4242498 s...@szepe.net skype: szepe.viktor Budapest, III. kerület -- Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot ___ courier-users mailing list courier-users@lists.sourceforge.net Unsubscribe: https://lists.sourceforge.net/lists/listinfo/courier-users
Re: [courier-users] monitoring prgram times out
SZÉPE Viktor writes: 2) Is it possible for Courier to skip DNS lookups for "localhost"? I wonder why Courier is not using gethostbyname(). /etc/hosts contains: 127.0.0.1 localhost.localdomain localhost gethostbyname/gethostbyaddr can only look up A addresses. Courier needs MX records, and so needs to use its own resolver; and with its own DNS resolver code already in place, it makes no sense to use different resolvers. There are several options in the esmtpd config file that control DNS lookups on incoming connections: BOFHCHECKDNS; and TCPDOPTS passes through the options to couriertcpd, such as -nodnslookup. pgpmDsSvVVMSa.pgp Description: PGP signature -- Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot___ courier-users mailing list courier-users@lists.sourceforge.net Unsubscribe: https://lists.sourceforge.net/lists/listinfo/courier-users