modified on 21 lip 2010 at 10:33 ••• 4 374 views

IP/TFTP

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Summary

TFTP is a very simple protocol used to transfer files. It is from this that its name comes, Trivial File Transfer Protocol or TFTP. Each nonterminal packet is acknowledged separately. RouterOS has a built-in TFTP server since v3.22

Requirements

Since version 4.4 to set up tftp rules you will have to have policy sensitive enabled for your account.

TFTP access rules

Menu: /ip tftp This menu contains all TFTP access rules. If in this menu are no rules, TFTP server is not started when RouterOS boots. This menu only shows 1 additional attribute compared to what you can set when creating rule, see explanations of attribute descriptions lower.

Property Desciption
hits how many times this access rule entry has been used (read-only)

Add new access rule

Expansion of command: /ip tftp add

To add new tftp access rule you will have to issue command add under /ip tftp menu with attributes as follows:

Property Desciption
ip-address (required) range of IP addresses accepted as clients if empty 0.0.0.0/0 will be used
req-filename requested filename as regular expression (regex) if field is left empty it defaults to .*
real-filename if above two values are set and valid, the requested filename will be replaced with this. If this field has to be set. If multiple regex are specified in req-filename, with this field you can set which ones should match, so this rule is validated. real-filename format for using multiple regex is filename\0\5\6
allow (default: yes) to allow connection if above fields are set. if no, connection will be interrupted
read-only (default: no) sets if file can be written to, if set to "no" write attempt will fail with error


req-filename field allowed regexp

allowed regexps in this field are

  • brackets () - marking subsection
    example 1 a(sd|fg) will match asd or afg
  • asterisk "*" - match zero or more times preceding symbol,
    example 1 a* will match any length name consisting purely of symbols a or no symbols at all
    example 2 .* will match any length name, also, empty field
    example 3 as*df will match adf, asdf, assdf, asssdf etc.
  • plus "+" will match one or more times preceding symbol,
    example: as+df will match asdf, assdf etc.
  • dot "." - matches any symbol
    example as.f will match asdf, asbf ashf etc.
  • square brackets [] - variation between
    example as[df] will match asd and asf
  • question mark "?" will match one or none symbols,
    example asd?f will match asdf and asf
  • caret "^" - used at the beginning of the line means that line starts with,
  • dollar "$" - means at the end of the line

Examples

  • example 1 if file is requested return file from store called sata1:
/ip tftp add req-filename=file.txt real-filename=/sata1/file.txt allow=yes read-only=yes
  • example 2 if we want to give out one specific file no matter what user is requesting:
/ip tftp add req-filename=.* real-filename=/sata1/file.txt allow=yes read-only=yes
  • example 3 if user requests aaa.bin or bbb.bin then give them ccc.bin:
/ip tftp add req-filename="(aaa.bin)|(bbb.bin)" real-filename="/sata1/ccc.bin\\0" allow=yes read-only=yes