Does your ISP block port 25 (SMTP)?

If you’re like me and are fortunate enough to have your own external SMTP server (which is just about anyone with dedicated or VPS web hosting) here’s a simple but really neat trick….. configure your SMTP service (exim, postfix, et al) to listen on port 587 as well as port 25….. according to the IETF, port 587 is officially reserved for SMTP anyway! Most ISPs cruel enough to block port 25 probably won’t block port 587. And hey, if they do, use a different port…. 26, 8025, 8587, just make sure it’s not something used by another service.

The other side of the equation is your mail client….. alter your SMTP settings and change the port to the new one you specified in your MTA config. It’s possible (I’ve not tested it) that using SSL or TLS may yield positive results too…. I’m not sure if this particular nameless ISP (run by a monopolistic behemoth telco in Australia, hint hint) blocks secure SMTP or not, but I might give it a try and swing an update to this post with my results.

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mount.cifs and permissions problems under ubuntu linux

Recently, I’ve had an issue using mount.cifs from the command line in linux to mount shares, on Ubuntu Linux (as a client).

The problem was, mounting a samba share using CIFS and using only the samba username/password would render the entire mount unwriteable, except by root.

The dead simple solution to this is as follows.

Instead of doing just this:

mount.cifs //<server>/<share> -ouser=<username>,pass=<password>

Try this:

mount.cifs //<server>/<share> -ouid=<localuser>,gid=<localgroup>,user=<username>,pass=<password>

So if your samba username is joe.bloggs, and your username and group on your local machine are just “joe”, you’d do this:

mount.cifs //<server>/<share> -ouid=joe,gid=joe,user=joe.bloggs,pass=<password>

This simply tells CIFS that user ‘joe’ on the local machine should be the owner of the mounted share, and then subject to whatever permissions the samba server has set.

Easy as!

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