How to format WHOIS response - bash

Question

I need to implement a "whois" service, that will be listening for whois queries (whois -h ) and will respond with information from phpipam API. I am listening on port 43 with xinetd that starts script.
My problem is that when I send a response from the server, the server after first new line, resets connection. For testing purposes I am simply trying to send two echo lines and result is the same.
Script:
#!/bin/bash
echo "One"
echo "Two"
lsof:
# lsof -i | grep whois
xinetd 17696 root 6u IPv4 91809 0t0 TCP *:whois (LISTEN)
whois query (from client):
# whois -h 192.168.4.129 44.44.44.44
One
fgets: Connection reset by peer
tcpdump:
# tcpdump -n -i any -X port 43
16:34:01.162440 IP 192.168.4.128.49374 > 192.168.4.129.nicname: Flags [S], seq 1949234703, win 29200, options [mss 1460,sackOK,TS val 337480796 ecr 0,nop,wscale 7], length 0
0x0000: 4500 003c 7a53 4000 4006 3617 c0a8 0480 E..<zS#.#.6.....
0x0010: c0a8 0481 c0de 002b 742e f60f 0000 0000 .......+t.......
0x0020: a002 7210 8a80 0000 0204 05b4 0402 080a ..r.............
0x0030: 141d 8c5c 0000 0000 0103 0307 0000 0000 ...\............
0x0040: 0000 0000 0000 0000 0000 0000 ............
16:34:01.162916 IP 192.168.4.129.nicname > 192.168.4.128.49374: Flags [S.], seq 3654394026, ack 1949234704, win 28960, options [mss 1460,sackOK,TS val 25631110 ecr 337480796,nop,wscale 7], length 0
0x0000: 4500 003c 0000 4000 4006 b06a c0a8 0481 E..<..#.#..j....
0x0010: c0a8 0480 002b c0de d9d1 a0aa 742e f610 .....+......t...
0x0020: a012 7120 eb31 0000 0204 05b4 0402 080a ..q..1..........
0x0030: 0187 1986 141d 8c5c 0103 0307 0000 0000 .......\........
0x0040: 0000 0000 0000 0000 0000 0000 ............
16:34:01.162946 IP 192.168.4.128.49374 > 192.168.4.129.nicname: Flags [.], ack 1, win 229, options [nop,nop,TS val 337480797 ecr 25631110], length 0
0x0000: 4500 0034 7a54 4000 4006 361e c0a8 0480 E..4zT#.#.6.....
0x0010: c0a8 0481 c0de 002b 742e f610 d9d1 a0ab .......+t.......
0x0020: 8010 00e5 8a78 0000 0101 080a 141d 8c5d .....x.........]
0x0030: 0187 1986 0000 0000 0000 0000 0000 0000 ................
0x0040: 0000 0000 ....
16:34:01.163348 IP 192.168.4.128.49374 > 192.168.4.129.nicname: Flags [P.], seq 1:14, ack 1, win 229, options [nop,nop,TS val 337480798 ecr 25631110], length 13
0x0000: 4500 0041 7a55 4000 4006 3610 c0a8 0480 E..AzU#.#.6.....
0x0010: c0a8 0481 c0de 002b 742e f610 d9d1 a0ab .......+t.......
0x0020: 8018 00e5 8a85 0000 0101 080a 141d 8c5e ...............^
0x0030: 0187 1986 3434 2e34 342e 3434 2e34 340d ....44.44.44.44.
0x0040: 0a00 0000 0000 0000 0000 0000 0000 0000 ................
0x0050: 00 .
16:34:01.164122 IP 192.168.4.129.nicname > 192.168.4.128.49374: Flags [.], ack 14, win 227, options [nop,nop,TS val 25631110 ecr 337480798], length 0
0x0000: 4500 0034 b92d 4000 4006 f744 c0a8 0481 E..4.-#.#..D....
0x0010: c0a8 0480 002b c0de d9d1 a0ab 742e f61d .....+......t...
0x0020: 8010 00e3 8a2c 0000 0101 080a 0187 1986 .....,..........
0x0030: 141d 8c5e 0000 0000 0000 0000 0000 0000 ...^............
0x0040: 0000 0000 ....
16:34:01.165523 IP 192.168.4.129.nicname > 192.168.4.128.49374: Flags [P.], seq 1:5, ack 14, win 227, options [nop,nop,TS val 25631110 ecr 337480798], length 4
0x0000: 4500 0038 b92e 4000 4006 f73f c0a8 0481 E..8..#.#..?....
0x0010: c0a8 0480 002b c0de d9d1 a0ab 742e f61d .....+......t...
0x0020: 8018 00e3 d5a7 0000 0101 080a 0187 1986 ................
0x0030: 141d 8c5e 4f6e 650a 0000 0000 0000 0000 ...^One.........
0x0040: 0000 0000 0000 0000 ........
16:34:01.165844 IP 192.168.4.128.49374 > 192.168.4.129.nicname: Flags [.], ack 5, win 229, options [nop,nop,TS val 337480800 ecr 25631110], length 0
0x0000: 4500 0034 7a56 4000 4006 361c c0a8 0480 E..4zV#.#.6.....
0x0010: c0a8 0481 c0de 002b 742e f61d d9d1 a0af .......+t.......
0x0020: 8010 00e5 8a78 0000 0101 080a 141d 8c60 .....x.........`
0x0030: 0187 1986 0000 0000 0000 0000 0000 0000 ................
0x0040: 0000 0000 ....
16:34:01.165914 IP 192.168.4.129.nicname > 192.168.4.128.49374: Flags [R.], seq 5, ack 14, win 227, options [nop,nop,TS val 25631111 ecr 337480798], length 0
0x0000: 4500 0034 b92f 4000 4006 f742 c0a8 0481 E..4./#.#..B....
0x0010: c0a8 0480 002b c0de d9d1 a0af 742e f61d .....+......t...
0x0020: 8014 00e3 8a23 0000 0101 080a 0187 1987 .....#..........
0x0030: 141d 8c5e 0000 0000 0000 0000 0000 0000 ...^............
0x0040: 0000 0000 ....
16:34:01.166350 IP 192.168.4.129.nicname > 192.168.4.128.49374: Flags [R], seq 3654394031, win 0, length 0
0x0000: 4500 0028 826a 4000 4006 2e14 c0a8 0481 E..(.j#.#.......
0x0010: c0a8 0480 002b c0de d9d1 a0af 0000 0000 .....+..........
0x0020: 5004 0000 ea03 0000 0000 0000 0000 0000 P...............
0x0030: 0000 0000 0000 0000 0000 0000 0000 ..............
If I try to connect to 43 with telnet, everything work fine:
# telnet 192.168.4.129 43
Trying 192.168.4.129...
Connected to 192.168.4.129.
Escape character is '^]'.
One
Two
Connection closed by foreign host.
UPDATE:
Loop like this works fine
while read line; do
echo "One"
echo "Two"
break
done
But still I can't understand why it is not working by just passing two echo lines, or even if I try to run a while loop with counter:
#!/bin/bash
COUNT=0
while [ $COUNT -lt 5 ]; do
echo The counter is $COUNT
let COUNT=COUNT+1
done
It stops after the first cycle:
# whois -h 192.168.4.129 44.44.44.44
The counter is 0
fgets: Connection reset by peer
Maybe you have any ideas, what is the reason/difference between these two loops?
My /etc/xinetd.d/whoistest:
service whois
{
port = 43
flags = REUSE
socket_type = stream
protocol = tcp
user = root
wait = no
type = UNLISTED
server = /path/to/shell/script
disable = no
log_type = SYSLOG authpriv
log_on_failure += USERID
}
Any support will be appreciated.

Answer 1

You need to make sure your xinetd is configured correctly. Your script also needs to handle input from whois client. This works:
#!/bin/bash
while read line; do
echo $line
echo "foo"
break
done
This reads your line, echoes it back and then something. Feel free to replace echo $line with echo whatever you want.
I had to configure xinetd like this for it to work:
service whois
{
port = 43
flags = REUSE
socket_type = stream
protocol = tcp
user = root
wait = no
type = UNLISTED
server = /tmp/w.sh
disable = no
}
Hope this helps. If your xinetd service is configured wrong, it just seems to drop the connection. If your server doesn't actually listen to input from client, you'll get connection reset by peer errors.
Hannu