telnetd vs telnetd -a


 
Thread Tools Search this Thread
Special Forums Cybersecurity telnetd vs telnetd -a
# 1  
Old 07-21-2006
telnetd vs telnetd -a

Hi folks. I have a quick question on using "telnetd" vs. "telnetd -a".

OS: AIX 5.x (5.1 through 5.3 ML3)

Some engineers at work want to stop using "telnetd -a" and use "telnetd".
(and of course, if I could get a cogent answer from them, I wouldn't be posting this question...) Smilie

The man page for telnetd suggests that "telnetd -a" offers improved performance as follows:

-a Causes the PTY and socket to be linked directly in the kernel so that the data handling remains in the kernel to improve the performance.

I don't see a security issue here, so I'm guessing that there might be a memory issue related to this.

Barring a call to IBM (which I'm about to make), does anyone have a quick answer as to why *not* to use -a, or which option is preferred? Smilie

Thanks!

-Dave
Login or Register to Ask a Question

Previous Thread | Next Thread

8 More Discussions You Might Find Interesting

1. AIX

telnetd daemon

Hi, When a client connected to AIX server by telnet is killed/crashes, is there a way for telnetd to recognize that and close/kill the application linked/started by that telnet session? We have a situation where clients disconnect because of frequent network outages, this leaves the... (2 Replies)
Discussion started by: mreyaz
2 Replies

2. SCO

Telnetd Port Options

Ok, here i am in 2008 trying to figure out how to edit the port of Telnetd in sco openserver 4.2. I googled my butt off and cant seem to find any info. Does anyone have some specific howto's or good documentation on this? (2 Replies)
Discussion started by: j0ntar
2 Replies

3. Solaris

Can't start telnetd

Hello all, I've got a problem on a V240 running Solaris 9, the telnet daemon won't start. The error message I get is "telnetd: stdin is not a socket file descriptor." I've never seen this message before and I'm not exactly sure what it means. I know generally what stdin, sockets, and file... (4 Replies)
Discussion started by: ONEX
4 Replies

4. Solaris

telnetd bug!

hi mates, a very important info for all solaris admins, there is a bug in telnetd on nearly every solaris version: pressy@mp-wst01 # id uid=100(pressy) gid=1(other) pressy@mp-wst01 # telnet -l "-froot" 192.168.40.1 Trying 192.168.40.1... Connected to 192.168.40.1. Escape character is... (3 Replies)
Discussion started by: pressy
3 Replies

5. UNIX for Dummies Questions & Answers

telnetd: all network ports in use

I hope someone can enlighten me on this. A few weeks ago, the root file system my UnixWare 7.1.1 server became corrupt so I ended up doing a full restore of the OS from tape backup. Since then, after I get about 270 users on the system, the message "telnetd: all network ports in use" is... (1 Reply)
Discussion started by: davekox
1 Replies

6. UNIX for Dummies Questions & Answers

Get telnetd to start a process other than login

I want to be able to get telnetd to start a program of my choice or one that I have written . . . or . . . write a daemon of my own to listen on a port other than 23 and when a connection arrives it should create a controlling tty/pty and then launch my program on the client side of the pty. A... (2 Replies)
Discussion started by: pdenaro
2 Replies

7. IP Networking

in.telnetd[5115] -- compromised?

/* Linux Slackware */ looking in my logs I see tons of entries similar to below. Does anyone know what these mean, and should I be concerned. I looked up a few of the IP's at Arin.net and saw that many of them belong to isp's (not good).. Any information is helpful.. Body of Messages log... (1 Reply)
Discussion started by: LowOrderBit
1 Replies

8. UNIX for Dummies Questions & Answers

Linux and in.telnetd problems

Hi, This is not the usual "unable to telnet to my machine" post. I: * have ensured that in.telnetd is started from inet.conf * that hosts.allow/deny are correctly configured * in.telnetd is listening, and on the correct port When I check my syslog i notice that tcpd (as I have... (3 Replies)
Discussion started by: sam_pointer
3 Replies
Login or Register to Ask a Question
telnetd(8)						      System Manager's Manual							telnetd(8)

NAME
telnetd - The DARPA telnet protocol server SYNOPSIS
telnetd [-debug [port]] [-D modifier ...] FLAGS
Starts telnetd manually, rather than through inetd, on alternate TCP port number port (if specified). Prints out debugging information. modifiers are: Prints information about negotiation of telnet options Same as options with additional processing information Displays the data stream received by telnetd Displays data written to the pty Not yet implemented DESCRIPTION
The telnetd daemon is a server that supports the DARPA (Defense Advanced Research Projects Agency) standard telnet virtual terminal proto- col. telnetd is invoked by the Internet server (see inetd(8)) normally for requests to connect to the telnet port as indicated by the /etc/services file (see services(4)). The -debug flag may be used, to start up telnetd manually. If started up this way, port may be specified to run telnetd on an alternate TCP port number. The -D options may be used for debugging purposes. This allows telnetd to print out debugging information to the connection, allowing the user to see what telnetd is doing. The telnetd daemon operates by allocating a pseudoterminal device (see pty(7)) for a client, then creating a login process that has the slave side of the pseudoterminal as stdin, stdout, and stderr. telnetd manipulates the master side of the pseudo-terminal, implementing the telnet protocol and passing characters between the remote client and the login process. When a telnet session is started up, telnetd sends telnet options to the client side, indicating a willingness to do remote echo of charac- ters, to suppress go ahead, to do remote flow control, and to receive terminal type information, terminal speed information, and window size information from the remote client. If the remote client is willing, the remote terminal type is propagated in the environment of the created login process. The pseudoterminal allocated to the client is configured to operate in cooked mode, and with XTABS and CRMOD enabled (see tty(7)). The telnetd daemon is willing to do: echo, binary, suppress go ahead, and timing mark. telnetd is willing to have the remote client do: line mode, binary, terminal type, terminal speed, window size, toggle flow control, environment, X display location, and suppress go ahead. The telnetd daemon never sends telnet go ahead commands. Note that binary mode has no common interpretation except between similar operating systems (Unix compatible systems in this case). Note also that the terminal type name received from the remote client is converted to lowercase. The telnet command uses the default Type-of-Service value recommended by RFC1060, which is as follows: Low delay You can configure this value by specifying it in the /etc/iptos file. For more information, see iptos(4). By default, the telnetd daemon starts the login dialog using the login string specified in the message field of the /etc/gettydefs file. If you want to use a customized banner, create an /etc/issue.net or /etc/issue file. The telnetd daemon reads the file that exists and writes its contents over a new telnet connection prior to starting the login dialog. If both files exist, only the /etc/issue.net file is used. CAUTIONS
Some telnet commands are only partially implemented. Because of bugs in the original 4.2BSD telnet(1), telnetd performs some dubious protocol exchanges to try to discover if the remote client is, in fact, a 4.2BSD telnet(1). FILES
Specifies the command path. Specifies the path name for the network issue identification file. Specifies the path name for the issue identification file. RELATED INFORMATION
Commands: telnet(1). Files: iptos(4), issue(4), issue.net(4). delim off telnetd(8)