Character Generator Protocol: Difference between revisions

Revision as of 01:25, 12 May 2025

Revision as of 13:01, 12 May 2025

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{{one source|date=October 2015}}

{{Infobox networking protocol

| title = Character Generator Protocol

| logo =

| logo alt =

| image =

| image alt =

| caption =

| is stack = No

| abbreviation = CHARGEN

| purpose = {{Unbulleted list|Testing|Debugging|Measurement}}

| developer = [[Jon Postel]]

| date = {{Start date and age|1983}}

| based on =

| influenced =

| osilayer = [[Application layer]] (7)

| ports = tcp/19, udp/19

| rfcs = {{IETF RFC|864}}

| hardware =

}}

{{IPstack}}

The '''Character Generator Protocol''' ('''CHARGEN''') is a service of the [[Internet Protocol Suite]] defined in {{IETF RFC|864}} in 1983 by [[Jon Postel]]. It is intended for testing, debugging, and measurement purposes. The protocol is rarely used, as its design flaws allow for ready misuse.<ref>{{Cite web|url=https://nvd.nist.gov/vuln/detail/CVE-1999-0103|title=NVD - CVE-1999-0103|website=nvd.nist.gov|access-date=2018-02-05}}</ref>

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This continues until the TCP connection is closed as shown in the trace by ending the telnet session.

== Visual Outputoutput Simulationsimulation ==

For security reasons, most modern machines should have CHARGEN services disabled. The following is a Linux bash script that will simulate the visual appearance of the CHARGEN service in the terminal window. The script can be stopped by pressing Ctrl + C.<syntaxhighlight lang="bash">

strg=""; for n in {32..126}; do c=`printf '%x' $n | xxd -r -p`; strg=${strg}${c}; done; strg=${strg}${strg}; n=0; while :; do m=n%95; echo "${strg:m:72}"; n=$((n+1)); sleep .1; done;

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==See also==

{{Portal|Internet}}

* [[Barber pole#Computer science|Barber pole]]

* [[Echo Protocol]]