I don't think there's any looking up by name--in the
example the IP was grabbed with getpeername
the name isn't known. If you were to get the ip with
and then use gethostbyaddr
result, you would be verifying it as they suggest, just
Quoting extensively from the Cookbook:
"...If you want the name of the remote end, call
gethostbyaddr to look up the name of the machine
in the DNS tables, right?
"Not really. That's only half the solution.
Because a name lookup goes to the name's owner's DNS
server and a lookup of an IP addresses goes to the
address's owner's DNS server, you have to contend with
the possibility that the machine that connecteed to you
is giving incorrect names. For instance, the machine
evil.crackers.org could belong to malevolent
cyberpirates who tell their DNS server that its IP address
(220.127.116.11) should be identified as
trusted.dod.gov. If your program trusts
trusted.dod.gov, a connection from
evil.crackers.org will cause getpeername to
return the right IP address (18.104.22.168), but
gethostbyaddr will return the duplicitous name
"To avoid this problem, we take the (possibly deceitful)
name returned by gethostbyaddr and look it up again
I'm just repeating, but it looks to me as if this is
talking about gethostbyaddr having the potential
to give incorrect information.
Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
Read Where should I post X? if you're not absolutely sure you're posting in the right place.
Please read these before you post! —
Posts may use any of the Perl Monks Approved HTML tags:
You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
- a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
Link using PerlMonks shortcuts! What shortcuts can I use for linking?
See Writeup Formatting Tips and other pages linked from there for more info.
| & || & |
| < || < |
| > || > |
| [ || [ |
| ] || ] ||