A: Книги и журналы
http://www.oreilly.com/catalog/sendmail2
Linux Network Admin Guide (NAG):
http://www.oreilly.com/catalog/linag
http://www.oreilly.com/catalog/runux2/noframes.html
http://www.oreilly.com/catalog/dns3
http://www.oreilly.com/catalog/apache2
http://www.oreilly.com/catalog/bash2
http://www.oreilly.com/catalog/fire
http://www.oreilly.com/catalog/crime
http://www.oreilly.com/catalog/csb
http://www.oreilly.com/catalog/crackdes
Essential System Administration:
http://www.oreilly.com/catalog/esa2
http://www.oreilly.com/catalog/linuxnut2
http://www.oreilly.com/catalog/nfs
http://www.oreilly.com/catalog/musenet/
http://www.oreilly.com/catalog/pgp
Practical Unix and Internet Security:
http://www.oreilly.com/catalog/puis
http://www.oreilly.com/catalog/runux2
http://www.oreilly.com/catalog/umppp/
http://www.oreilly.com/catalog/vpn2/
Red Hat/SAMS also publish several interesting books:
Maximum RPM (available as a postscript document on http://www.rpm.org)
Red Hat User's Guide (available as HTML on ftp://ftp.redhat.com)
SNMP, SNMPv2 and RMON - W. Stallings (ISBN: 0-201-63479-1)
Magazines:
Linux Journal (of course, monthly)
Sys Admin (intelligent articles, monthly)
Perl Journal (quarterly)
http://www.infosecuritymag.com