Paul Howarth wrote: > Don Russell wrote: >> On 4/4/2006 4:29 AM, Paul Howarth wrote: >>> Don Russell wrote: >>>> I'm using FC5 and have the "nightly yum update" turned on. >>>> My FC5 box runs a mail server. >>>> Yesterday, there were no problems. >>>> Today, I can't send mail from PCs on the network... the Thunderbird >> client >>>> says "Connected to 10...." and eventuaally times out. >>>>> From external machines I can telnet to port 25 and it takes anywhere >> from >>>> 40-80 seconds to get a reply from the server. >>>> If I'm on the same machine as the server, the connection is immediate. >> That tells me it is not smtp that's slow, but something relating to external connections. >>>> I have not changed any configurations... but with the nightly updates, >> what could account for introducing such a delay? >>>> I'm thinking somethin like it's trying to a reverse dns look up to >> check >>>> the address connecting, and that's taking a long time? >>>> Any ideas/suggestions? >>> Check that your nsswitch.conf has an appropriate hosts entry. >> hmmm, I don't know what's "appropriate". :-( >> The nsswitch.conf file looks pretty generic... the "hosts" line says: hosts: files dns > That looks OK. >> Guessing, I changed that to >> hosts: files dns [NOTFOUND=return] >> then "service network restart" >> but that had no effect... >> hmmm, do I need to have my PCs listed in /etc/hosts ? > No. Sendmail needs to look up MX records, which it can't get from a hosts file anyway. So why does the host line say "files dns" and not just "dns"? (Off track... I'm just curious) Regardless... if sendmail is looking for an MX recod to be associated with the sender address for me, it likely won't find one. But, that is nothing new... I use DynDNS to map a name to my ISP IP address and run a mail server at home. >> If so, that means something changed because this was all working fine the >> other day... could a "nightly yum" have wiped out my /etc/hosts file? > Which new packages were installed on the night in question? (check /var/log/yum.log) hmm, tons of stuff... I actually went back a day or to prior... Mar 29 20:56:48 Updated: libselinux-devel.i386 1.30-1.fc5 Mar 29 20:57:25 Installed: kernel.i686 2.6.16-1.2080_FC5 Mar 29 20:57:30 Updated: libselinux.i386 1.30-1.fc5 Mar 29 20:57:32 Updated: libsemanage.i386 1.6-1.fc5 Mar 29 20:57:32 Updated: libselinux-python.i386 1.30-1.fc5 Mar 29 20:57:34 Updated: policycoreutils.i386 1.30.1-2.fc5 Mar 29 20:57:35 Updated: libsetrans.i386 0.1.20-1.fc5 Mar 29 20:57:41 Updated: selinux-policy.noarch 2.2.25-2.fc5 Mar 29 20:57:51 Updated: selinux-policy-targeted.noarch 2.2.25-2.fc5 Mar 29 20:57:55 Erased: iiimf-libs Mar 31 04:25:26 Updated: samba-common.i386 3.0.22-1.fc5 Mar 31 04:25:36 Updated: mrtg.i386 2.13.2-0.fc5.1 Mar 31 04:25:59 Updated: samba.i386 3.0.22-1.fc5 Mar 31 04:26:01 Updated: wpa_supplicant.i386 1:0.4.8-6.fc5 Mar 31 04:26:04 Updated: samba-client.i386 3.0.22-1.fc5 Apr 01 04:13:08 Updated: koffice-core.i386 1.5.0-0.1.rc1.fc5 Apr 01 04:13:13 Updated: koffice-karbon.i386 1.5.0-0.1.rc1.fc5 Apr 01 04:13:18 Updated: koffice-filters.i386 1.5.0-0.1.rc1.fc5 Apr 01 04:13:24 Updated: koffice-kspread.i386 1.5.0-0.1.rc1.fc5 Apr 01 04:13:27 Updated: koffice-kplato.i386 1.5.0-0.1.rc1.fc5 Apr 01 04:13:43 Updated: koffice-kivio.i386 1.5.0-0.1.rc1.fc5 Apr 01 04:13:51 Updated: koffice-kpresenter.i386 1.5.0-0.1.rc1.fc5 Apr 01 04:13:54 Updated: koffice-kugar.i386 1.5.0-0.1.rc1.fc5 Apr 01 04:13:57 Updated: koffice-kchart.i386 1.5.0-0.1.rc1.fc5 Apr 01 04:14:04 Updated: koffice-kword.i386 1.5.0-0.1.rc1.fc5 Apr 01 04:14:06 Updated: koffice-kformula.i386 1.5.0-0.1.rc1.fc5 Apr 01 04:14:09 Updated: yumex.noarch 0.99.15-1.0.fc5 Apr 01 04:14:21 Updated: koffice-krita.i386 1.5.0-0.1.rc1.fc5 Apr 01 04:14:28 Updated: koffice-kexi.i386 1.5.0-0.1.rc1.fc5 Apr 01 04:14:28 Updated: koffice-suite.i386 1.5.0-0.1.rc1.fc5 Apr 02 05:40:51 Updated: dia.i386 1:0.94-21 Apr 03 14:51:59 Updated: policycoreutils.i386 1.30.1-3.fc5 Note: This policycoreutils update was done AFTER I discovered the problem... FYI: I run SELinux in permissive mode... so, I supose even if this is some sort of SE issue, it should be transparent and show up as a violation warning in my Logwatch report... >>> Check that /etc/resolv.conf points to nameservers that are working. Try using "dig" to check them out, e.g. >>> $ dig @first.name.server -x 212.56.100.58 >>> See how long the lookups take. >> I tried several times with the two dns addresses in /etc/resolv.conf and >> the longest query time was 180mSec, the shortest was 25mSec. >> However, I also tried dig @dns-server - x 10.10.10.13 >> (the 10. address is my PC that tries to connect to my mail server at 10.10.10.250) >> That timed out after 15 seconds.... expected, but far short of the delay I >> see when I "telnet 10.10.10.250 25" from 10.10.10.13 > Doesn't really sound like a DNS issue then. See my other post where I notice my router firewall is blocking udp port 1078 coming from the DNS server. I have no idea why I'm getting udp 1078 traffic from a DNS server... but I'm not a DNS expert... FWIW.. I also notice a slow down in connecting to this machine via ssh. i.e. from an ssh client on 10.10.10.13 on Windows XP, ssh'ing to 10.10.10.250 (where my mail server is) takes longer to respond with the password prompt than it used to.... so something is going on there too. Thanks... I appreciate the tips.... :-) Don
