Solved

zmodem - what type of protocol is it..? layer 3 or layer 4 ? more...

Posted on 2001-06-06
4
424 Views
Last Modified: 2013-12-23
guys,

is zmodem (zmtx/zmrx) a layer 3 (like tcp/udp) or layer 4 protocol (like ftp?).. I am running a server with no telnet and only SSH2 access, and we use zmodem to transfer files to and fro our local PCs. I would like to know what type of protocol is it and how it relates to firewall rules / port numbers...

does zmodem tunnel through SSH in this case?
Please advice.
Thanks
0
Comment
Question by:thiamwah
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 2
4 Comments
 
LVL 40

Expert Comment

by:jlevie
ID: 6159432
zmodem is a serial file transfer protocl and as such is completely separate from networking protocols. It was originally delevloped as a replacement for xmodem, which in turn was developed as an alternative to kermit. All of these are a means of copying files over a simple serial connection like you'd have in the case of a direct modem dial-up directly to a remote server. They were very popular and widely used before the days of dial-up networking and are quite efficient over low speed dial-up connections (<9600baud).

The most appropriate way to transfer files between a remote client and a remote server that only offers ssh access is to use scp. The putty client for windows (http://www.chiark.greenend.org.uk/~sgtatham/putty/) includes a command line scp program and there are Gui clients for windows like WinSCP (http://winscp.vse.cz/eng/).
0
 

Author Comment

by:thiamwah
ID: 6162181
so how does zmodem relate to firewall rules...?
As since I am using SSH2 to telnet, when I use zmodem to transfer or put files in the server, is it tunnelled through SSH (TCP/port 22)?

0
 
LVL 4

Expert Comment

by:newmang
ID: 6162238
The short answer is that it doesn't. The firewall controls the ability to connect various addresses and ports through it, generally it doesn't look at the contents of the packets passed through it. zmodem is an application to application protocol not a comms protocol.
0
 
LVL 40

Accepted Solution

by:
jlevie earned 50 total points
ID: 6163977
newmang is quite correct, but another way of stating the relationship of zmodem to firewall rules is that since zmodem is an embedded application protocol that works "under" some other commuication protocol, it doesn't require special adjustments on a firewall. The communications protocol (ssh in this case) provides the transport conduit and zmodem simply uses that connection.
0

Featured Post

Easy, flexible multimedia distribution & control

Coming soon!  Ideal for large-scale A/V applications, ATEN's VM3200 Modular Matrix Switch is an all-in-one solution that simplifies video wall integration. Easily customize display layouts to see what you want, how you want it in 4k.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Title # Comments Views Activity
nested esxi, NIC issues 1 58
Price for Fiber 13 60
Unidentified Network 12 54
PoE Injector and switch 2 11
Don’t let your business fall victim to the coming apocalypse – use our Survival Guide for the Fax Apocalypse to identify the risks and signs of zombie fax activities at your business.
When it comes to security, there are always trade-offs between security and convenience/ease of administration. This article examines some of the main pros and cons of using key authentication vs password authentication for hosting an SFTP server.
After creating this article (http://www.experts-exchange.com/articles/23699/Setup-Mikrotik-routers-with-OSPF.html), I decided to make a video (no audio) to show you how to configure the routers and run some trace routes and pings between the 7 sites…
Get a first impression of how PRTG looks and learn how it works.   This video is a short introduction to PRTG, as an initial overview or as a quick start for new PRTG users.

740 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question