We recently moved to a new server running Debian Squeeze.
a few weeks after putting the server into production, I did a routine apt-get dist-upgrade. Usually there are no surprises.
But we noticed we could not access mail via pop3, and we could not log in to Webmin.
After a bit of research on logs, I discovered the issue related to Shorewall. Up until that point I had never even heard of Shorewall (obviously I'm not s security expert).
As a temporary fix I can issues a "shorewall clear" to gain access to mail, and later issue a "shorewall restart" to block it again.
But I have some questions:
- if this was installed or enabled by the dist-upgrade, then what did it replace? Is it really needed or necessary? (or better, what value does it have?)
- and where and how would I change the shorewall configuration so it doesn't block mail or webmin?