Re: [filtered-ww] [vps-mail] Issue re sendmail/ abuse (attempted relay????)

[Bruce Armstrong <bruce@xxxxxxxxxxxxxxxxxxxxx>]

	As far as I know, which might not be enough, it shouldn't be a
problem.  I have noticed that mail gets sent from the hostname of your
server.  This should be correct.  A simple test will tell you if you
need to fix something.

## Get the ip address of your server
server> sinfo
hostname: my.server.domain
address:  IP.ADD.RE.SS
type:     B (1)
server:   pysical.server
login:    login-name

## See what domain is associated with that address
server> host IP.ADD.RE.SS
SS.RE.ADD.IP.IN-ADDR.ARPA domain name pointer my.server.domain

## Verify that the domain has the correct ip
server> host my.server.domain
my.server.domain has address IP.ADD.RE.SS

	In summary, if the last two commands don't match, you have a problem. 
Unless you have changed the primary domain name since ordering the
account, you shouldn't have a problem.

	--Bruce

P.S. If the 'host' command isn't available on your system, nslookup will
also work.

On Sat, 2003-08-23 at 03:27, Tim Gorter wrote:
> On a bit of Internet search
> 
> man 5 hosts_access
> 
> one site that seems an easy read
> http://ezine.deamonnews.org/200206/hosts_allow.html
> 
> But now I have a question....
> If I enable reverse IP look up from within the hosts.allow file, will
> I end up blocking servers like my own VPS where the registered domain
> name (with IP) doesn't corresponds with any virtual domain name. ie.
> if someone sends mail from virtual.domain.name to a VPS, and PARANOID
> is used, will it get blocked as the IP address in reality is
> registered to another domain name. (The other discussion re: PTR)
> 
> cheers,
> tim.
> 
> Saturday, August 23, 2003, 7:41:57 AM, Bruce Armstrong wrote:
> 
> BA> I'll be responding inline.
> 
> BA> On Fri, 22 Aug 2003, Abigail Marshall wrote:
> 
> >> BA> On VPS1, tcpwrappers can be used to block the connection without even
> >> BA> starting a sendmail process.
> >>
> >> BA> There are some other interesting possibilities with tcpwrappers, worth
> >> BA> checking out.
> >>
> >> Bruce,
> >>
> >> All I can say is wow ... I have seen server load go down
> >> before my eyes, almost instantly.
> >>
> >> Can the hosts.allow file be used in lieu of domain or IP
> >> specific blocking in the Sendmail Access file?
> >>
> BA> Yes
> 
> >> Am I correct that it would work with even less impact on
> >> server resources, but that the difference would be that the
> >> sender would simply not be able to connect, as opposed to
> >> receiving a Sendmail-generated RFC error message?
> >>
> BA> You are correct
> 
> >> Or is hosts.allow only going to work against those attempting
> >> an SMTP relay connection, rather than rejecting email simply
> >> sent from another server to a domain on the VPS1?
> >>
> BA> The hosts.allow file is used by iservd to determine whether or not to
> BA> allow a connection to a particular service.  The comments in the default
> BA> hosts.allow list a number of services you can allow or deny access to.
> BA> Among them are telnet, ftp, pop3, imap, etc.  If a default hosts.allow
> BA> doesn't exist, you can find one in the skel directory.  Most of my servers
> BA> got the new file when the change happened, but some didn't (I thought
> BA> that was odd).  Anyway, if you specify that a host can't connect to a
> BA> service, then the connections will be flat out refused or dropped.
> 
> BA> Hope that helps. I'd direct you to the manpage, but it doesn't seem to
> BA> exist on the vps servers.
> 
> BA>         --Bruce
> 
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