[HowTo] Selective greylisting

[rbtux]

Hi there

this howto describes how to use greylisting within postfix only für unknow host or hostname that looks like they are coming out of dynamic ip ranges.

1. Install postfix pcre package

Quote:> apt-get install postfix-pcre

2. Create new file /etc/postfix/dynip.pcre
EDIT: Attention the long regex is one single line!!!

Quote:# everything with 4 or more dots/hyphens in the hostname
/(\-.+){4}$/ rc_greylisting
/(\..+){4}$/ rc_greylisting

# some well known dynamic patterns
/(^|[0-9.x_-])(abo|br(e|oa)dband|cabel|(hk)?cablep?|catv|cbl|cidr
|d?client2?|cust(omer)?s?|dhcp|dial?(in|up)?|d[iu]p|[asx]?dsld?|dyn(a(dsl|mic)?)?
|home|in-addr|modem(cable)?|(di)?pool|ppp|ptr|rev|user|YahooBB[0-9]{12}
|c[[:alnum:]]{6,}(\.[a-z]{3})?\.virtua|[1-9]Cust[0-9]+|AC[A-Z][0-9A-F]{5}\.ipt
|pcp[0-9]{6,}pcs|S0106[[:alnum:]]{12,}\.[a-z]{2})[0-9.x_-]/ rc_greylisting

# systems without a hostname
/^unknown$/ rc_greylisting

3. Change the main.cf

Add

Quote:smtpd_restriction_classes = rc_greylisting

rc_greylisting = check_policy_service inet:127.0.0.1:60000

Change in the smpd_recipient_restrictions:

Quote:check_policy_service inet:127.0.0.1:60000

to

Quote:check_client_access pcre:/etc/postfix/dynip.pcre

4. Thats it