the concept of throwing away auth by default sounds foolish. nevertheless, it's not the problem here.

# fgrep auth.info /etc/syslog.conf 
auth.info                       /var/log/auth
auth.info                       @authloghost

# logger -p auth.info "hello world"

# tail -1 /var/log/auth
Dec 21 16:22:04 host.sub.dom username: [ID 702911 auth.info] hello wor
+ld
[download]

meanwhile...

# perl -v

This is perl, v5.6.1 built for sun4-solaris

...

# perl -e 'use Sys::Syslog; syslog "auth.info", "from perl"'
syslog: invalid level/facility: auth at -e line 1

# perl -e 'use Sys::Syslog; sub Sys::Syslog::LOG_AUTH () { 4<<3 }; sys
+log "auth.info", "from perl"'

# tail -1 /var/log/auth
Dec 21 16:30:08 host.sub.dom username: from perl
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i've tried a fresh build of 5.6.1 using Sun's compiler and the auto-everything flags (-des). somehow when it builds the Sys::Syslog module it misses LOG_AUTH (even though it's in sys/syslog.h with everything else). 5.8.1 built with the same compiler/flags works properly. adding the missing function works as well.