[pmmail-list] firewalls

[Kenneth Porter]

On Tue, 27 Mar 2001 11:54:51 +0200 (MSZ), Andreas Ludwig wrote:

>Hm. Might this also be the reason why I have these long timeouts when
>connecting to my servers (SMTP without authentication)? But I have no
>firewall and the latest PMMail/2 beta.

That might be a reverse-DNS timeout. Does the IP you connect with have
a reverse-DNS entry? Sendmail checks this when receiving a connection.
Some lame ISP's don't provide them, so sendmail must wait for the
resolver to time out. Some ISP's are so lame that they run ancient
versions of BIND with known vulnerabilities. Just ran across one of
these the other day when researching a reverse-DNS failure in my mail
server logs.

Try "nslookup my.ip.address" (plugging in your assigned address). If
you have dig (can't remember if OS/2 provides that) run "dig -x
my.ip.address" to see a more complete trace of the DNS query.

Ken
mailto:shiva@well.com
http://www.sewingwitch.com/ken/
[If answering a mailing list posting, please don't cc me your reply. I'll take my answer on the list.]



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