Jon Snader's Home Page
- Jon C. Snader
5302 Rollinsford Ct.
Tampa, FL 33624
- PGP Key
VPNs Illustrated: Tunnels, VPNs, and IPsec
Now available from Addison-Wesley:
VPNs Illustrated: Tunnels, VPNs, and IPsec
- VPNs Illustrated is now available from
the publisher and other book sellers.
- Table of Contents
- Errata (last updated
April 8, 2010)
- Sample Chapter: Chapter 5: Virtual Private
Networks. Chapter 5 is a short introduction to
virtual private networks. The chapter, along with the
rest of Part 2, serves as a transition
between the tunneling technology discussed in Part 1 and
IPsec, which is discussed in Part 3.
Download Chapter 5 (ps,
- Source code and configuration files from the book
(gzipped tar file)
- Here are some
useful security links that
point to software mentioned in the book as well
as other useful information (last updated Sept. 18, 2006).
Effective TCP/IP Programming
Effective TCP/IP Programming, published by
Addison-Wesley, is now available.
Under Permanent Construction:
These are links that I use all the time to find information
- Rich Stevens's
contains links to his books, the source code described in them,
and has copies of many hard to find papers and email messages
Douglas Comer's Home Page
has links to information about his
networking books and TCP/IP stack
and to the XINU
- Craig Partridge's
has links to some of his papers, including
Reliable Data Protocol (RDP)."
source code for RDP is also available.
IETF Home Page
has lots of useful information, including links to the
Mailing Lists, and
Numbers Authority has the most up to date list of assigned
This is the place to look if you want to know what service uses
TCP port 25, what the ICMP message type and code parameters are,
or any of the many other numbers used by the Internet.
- The Lawrence Berkeley National Laboratory's
Networking Research Group
has links to many important networking research papers, as well
as source code distributions of important networking tools such
- Patches and updates to tcpdump and libpcap
are available from the
The latest versions are tcpdump v3.9.5 and libpcap v0.9.5.
See the tcpdump
for the new features added in this release.
has a version of tcpdump that runs under Microsoft Windows.
Also available are Windows versions of BPF and libpcap.
- A reimplementation of Van Jacobson's
is now available with source code.
The pchar utility attempts to characterize such end-to-end
characteristics as the latency and bandwidth of a network path.
TBIT home page has
information on tbit, the TCP Behavior Inference Tool.
Using tbit one can test the behavior of a remote TCP
stack. The software and papers describing the system are available
on the site.
- Geek Tools has some
useful software, a list of traceroute servers that allow
you to run a traceroute from most parts of the world, and
other useful resources.
- The ttcp test tool,
as described by Mike Muuss is available from
SGI. A version
with the enhanced statistics added by John Lin is
- Uri Raz's
TCP/IP Resources List
is an excellent starting place to find information about
It contains numerous links to web sites, books, FAQs, tutorials,
and other information.
- Google Groups
has a vast archive of postings from the Usenet News Groups.
Google has resurrected the Deja.com archive, after a long period
Google has managed to find copies of the early postings, and the
archive now goes back to 1981.
great story about it in Salon.
- Luigi Rizzo's
is a flexible traffic shaper and protocol testing tool.
Although dummynet is a part of
a stand alone version on a bootable floppy is also available.
Some folks at HP have ported dummynet to HP-UX 11/11i.
Although officially unsupported, you can get a copy from the
HP FTP Archive.
- Victor Abell's
is a must have tool for UNIX users needing to know
what processes have a file or socket open.
- Want to know some of the history of the ping utility,
or the real reason for its name?
Follow this link for
The Story of
the PING Program.
You'll also find a link to the ping source code there.
Usenet Info Center Launch Pad
is a great place to get information about Usenet and the newsgroups.
- Intermedia Communications has
Looking Glasses for various Public NAPs. These allow
you to check the BGP routing table, to run a traceroute or
ping from the NAP, and to check various other statistics
concerning the NAP.
For years I've used
these pages from Rich
Stevens as a handy reference for the layout of IP, TCP, and UDP
The problem is I have to keep them in a notebook, so
they aren't as portable as I'd like.
Recently, I received
pocket guide from the folks at the
The pocket guide format makes it easy to carry around, and to
keep copies in my briefcase, laptop carrying case, and other
There were still a few items missing, however.
For one thing, the names of the fields themselves were
Since I sometimes have to grub around in the headers, it's
useful to have the names handy.
There were a couple of other things, too.
For example, I can never remember the exact layout of the
Therefore, I made up my own
with the information that I usually need.
Perhaps you'll find it useful as well.
Updated 9/16/02: I added the (BSD) TCP state numbers,
which, believe it or not, turns out to be useful.
The netcat program is an extraordinarily useful tool.
It's a Unix utility that can read or write data
(hence “cat”) across a network connection using
either TCP or UDP.
It can perform
many of the tasks that I wrote special little programs
for in Effective TCP/IP Programming. Among its
many uses are scanning ports, file transfers, firewall
testing, and network performance testing.
It's available as a
FreeBSD Port, but a general distribution for other Unix systems
can be found
There's also a GNU version of netcat available at
SourceForge, which I haven't used.
Finally, there's a project to port netcat to
on SourceForge. That project appears to be in the early
There's a nice netcat
The hping utility is another extraordinarily
useful test tool. Despite its name, hping can send
TCP and UDP as well as ICMP packets, and it allows you
to control virtually all the flags and parameters in
those packets. For example, if you want see how your
TCP/IP stack handles a TCP packet with both the SYN and
FIN flags sets, hping makes it easy. It has more
capabilities than can be described here, so you should visit
its Web site for complete
details. Source code for Linux, *BSD, Solaris, and MacOS X
can be downloaded from the Web site. It's also available as
I recently came across
of an interesting lecture by
Van Jacobson, one of my heroes and surely one of the smartest
men in networking. It's well worth watching.
Last updated: $Date: 2010/04/08 15:37:50 $