Hot Downloads

Welcome, Guest
Username: Password: Remember me

TOPIC: Blocking TCP port 69 also blocks TFTP

Blocking TCP port 69 also blocks TFTP 8 years 4 months ago #26018

  • elp
  • elp's Avatar
  • Offline
  • New Member
  • Posts: 3
  • Karma: 0
Hello guys,

I have a basic question, although a little tricky for me to understand. I was configuring some ACLs on a router, here is the thing I was trying to block TFTP traffic but by mistake I block TCP 69 port instead of UDP 69, both configuration successfully blocks TFTP. But here is the question, how come that blocking TCP:69 also blocks TFTP as TFTP works on UDP:69?

Thanks in advance. : ).
The administrator has disabled public write access.

Re: Blocking TCP port 69 also blocks TFTP 8 years 4 months ago #26025

  • ikon
  • ikon's Avatar
  • Offline
  • Frequent Member
  • Posts: 48
  • Karma: 0
TFTP Uses Some features of the TCP Stack such as acknowledgments, so by blocking tcp on port 69 you are effectivly stopping tftp from be able to establish a proper session with the host.


There are a few applications that use both TCP and UDP like BOOTP, DNS, NFS, SNMP.

Although it is not specifically stated in the RFC for TFTP is is however the case.

Thanks
The administrator has disabled public write access.
Time to create page: 0.070 seconds

CCENT/CCNA

Cisco Routers

  • SSL WebVPN
  • Securing Routers
  • Policy Based Routing
  • Router on-a-Stick

VPN Security

  • Understand DMVPN
  • GRE/IPSec Configuration
  • Site-to-Site IPSec VPN
  • IPSec Modes

Cisco Help

  • VPN Client Windows 8
  • VPN Client Windows 7
  • CCP Display Problem
  • Cisco Support App.

Windows 2012

  • New Features
  • Licensing
  • Hyper-V / VDI
  • Install Hyper-V

Linux

  • File Permissions
  • Webmin
  • Groups - Users
  • Samba Setup