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Operating Systems => Linux and UNIX => Topic started by: Stryker on 11 October 2002, 03:29

Title: pause for some services
Post by: Stryker on 11 October 2002, 03:29

Recently I have started to notice a large lag (about 40 seconds) between when i connect to one of the services. (they are: smtp, pop3s, imap, telnet, ssh sometimes, smb) I've checked through most of the settings and cannot find anything wrong. Any ideas?

Title: pause for some services
Post by: voidmain on 11 October 2002, 04:08

Yes, it's very possibly the resolver. This is quite common. If you log in to the server can the server look up host names using nslookup? That is, is your /etc/resolv.conf properly configured?  If so, also check to make sure the "hosts" entry in /etc/nsswitch.conf looks like this:

hosts:  files dns

This means the resolver will first look at /etc/hosts and then use a DNS query. If your ip address is not in /etc/hosts and it can not do a reverse lookup by DNS on the server then it still might be a little slow unless you add an entry for your client's IP address and name in /etc/hosts on the server. That would at least be a good way to test if it is a resolver issue.

Actually rather than using "nslookup" to test if it's a resolver issue you should use "getent" like so:

getent hosts xxx.xxx.xxx.xxx

Which should return a host name, or at least return very quickly with no result if there is no reverse record.

Another thing it could be is that the server is trying to do an "ident" lookup on your client when you attempt to connect to it. If you configured a firewall on your client recently it may be causing the problem. Is that possible?

[ October 10, 2002: Message edited by: void main ]

Title: pause for some services
Post by: Stryker on 11 October 2002, 05:14

i added my private ip and the client's ip in /etc/hosts and all works well now, thanks voidmain.