-----Original Message----- From: centos-bounces@centos.org [mailto:centos-bounces@centos.org] On Behalf Of Paul Heinlein Sent: Friday, May 23, 2008 2:35 PM To: CentOS mailing list Subject: RE: [CentOS] how to debug ssh slow connection issues.
On Fri, 23 May 2008, Jason Pyeron wrote:
debug3: Normalising mapped IPv4 in IPv6 address debug3: Trying to reverse map address 192.168.1.80.
paused 7 seconds
Here, obviously, is part of the problem. Your name service isn't answering reverse lookups for your LAN addresses -- or it least it isn't answering them in a timely manner. Fixing that, either through DNS or /etc/hosts, will help a bunch.
[root@192.168.1.21 ~]# date && host 192.168.1.80 && date && host host80.1.internal.pdinc.us && date Fri May 23 13:55:52 EDT 2008 80.1.168.192.in-addr.arpa domain name pointer
host80.1.internal.pdinc.us.
Fri May 23 13:55:52 EDT 2008 host80.1.internal.pdinc.us has address 192.168.1.80 Fri May 23 13:55:52
EDT
2008 [root@192.168.1.21 ~]#
Hmmm, does not take 7 seconds.
User-space utilities like /usr/bin/host don't always provide an accurate reflection of the name services inherited by init- or kernel-launched processes -- especially if the network wasn't (for reasons unknown) fully functional at boot time.
Reboot?
Do you remember if there were any network timeouts when you booted the machine in question?
Oddly, yes there was.
Are you running nscd?
[root@devserver21 ~]# chkconfig --list | grep nscd nscd 0:off 1:off 2:off 3:off 4:off 5:off 6:off
I'm still inclined to believe that hostname-lookup issues are involved here; an strace with timestamps might provide a better glimpse of the exact system calls that are timing out.
Like wise, but with local DNS and local IPs humming perfectly?
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