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bash scripting help

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# 1  
Old 02-07-2009
bash scripting help
hi all

i'm trying to get a script working upon connection with pppd
According to docu this happens ina clean environment with a couple of variables set, namely $1,$2,...

To be able to execute the statements i included a path statement but i think i'm running into trouble with the variables - i get an invalid argument error.
(forgot to mention the script works fine from vanilla prompt as root - same credentials pppd uses to execute the script)

Code:
#!/bin/bash
export PATH
PATH="/usr/local/sbin:/usr/sbin:/sbin:/usr/local/bin:/bin:/usr/bin:PATH"
iptables -F 
dynip=$(ifconfig ppp0 | grep 'inet addr' | grep -v '127.0.0.1'| awk '{print $2}' | cut -d: -f2) 
iptables -t nat -A POSTROUTING -o ppp0 -j MASQUERADE
iptables -A FORWARD -i ppp0 -o eth0 -m state --state RELATED,ESTABLISHED -j ACCEPT
iptables -A FORWARD -i eth0 -o ppp0 -j ACCEPT
iptables -t nat -A PREROUTING -p tcp -i ppp0 -d $dynip --dport 16913 -j DNAT --to 192.168.0.10:16913
iptables -A FORWARD -p tcp -i ppp0 -d 192.168.0.10 --dport 16913 -j ACCEPT
iptables -t nat -A PREROUTING -p udp -i ppp0 -d $dynip --dport 16913 -j DNAT --to 192.168.0.10:16913
iptables -A FORWARD -p udp -i ppp0 -d 192.168.0.10 --dport 16913 -j ACCEPT
iptables -t nat -A PREROUTING -p tcp -i ppp0 -d $dynip --dport 62601 -j DNAT --to 192.168.0.10:62601
iptables -A FORWARD -p tcp -i ppp0 -d 192.168.0.10 --dport 62601 -j ACCEPT
iptables -t nat -A PREROUTING -p udp -i ppp0 -d $dynip --dport 62601 -j DNAT --to 192.168.0.10:62601
iptables -A FORWARD -p udp -i ppp0 -d 192.168.0.10 --dport 62601 -j ACCEPT
echo $dynip >> /etc/ppp/ip-up/log/nat.log
date >> /etc/ppp/ip-up/log/nat.log


i think this line gives the problem:
dynip=$(ifconfig ppp0 | grep 'inet addr' | grep -v '127.0.0.1'| awk '{print $2}' | cut -d: -f2)

is it possible that $2 is interpreted as the variable the script recieved from pppd on start instead of using the previous statement as input?
Last edited by vgersh99; 02-07-2009 at 12:33 PM.. Reason: vB Codes
# 2  
Old 02-07-2009
First off, please use vB Codes when posting either code or data samples - it makes easier to read for the other potential posters.

Secondly:
Code:
#!/bin/bash
# WHY exporting the PATH?
export PATH
# This is not the way to ADD to a current path - you missed '$'
# PATH="/usr/local/sbin:/usr/sbin:/sbin:/usr/local/bin:/bin:/usr/bin:$PATH"
iptables -F

# This is way too many pipes
#dynip=$(ifconfig ppp0 | grep 'inet addr' | grep -v '127.0.0.1'| awk '{print $2}' | cut -d: -f2) 
dynip=$(ifconfig ppp0 | awk '/inet addr/ && !/127.0.0.1/{print $2}' | cut -d: -f2)

You'll be able to get rid of the trailing 'cut' if you post a sample of your:
Code:
ifconfig ppp0

Quote:
Originally Posted by jimjones
is it possible that $2 is interpreted as the variable the script received from pppd on start instead of using the previous statement as input?
Hm... I don't understand what you're asking, but..... the awk's '$2' in this content refers to the SECOND field on a line that 'ifcong pppd' produces.

Pls post the output of 'ifconfig ppp0'.
# 3  
Old 02-07-2009
i did not say i was an expert at shellscripting Smilie
the export seemed cautious - but i'll remove it

the script has been made mostly from snippets i collected on the internet

here's what i get for ifconfig ppp0:
Code:
ppp0      Link encap:Point-to-Point Protocol  
          inet addr:91.86.57.229  P-t-P:91.86.32.1  Mask:255.255.255.255
          UP POINTOPOINT RUNNING NOARP MULTICAST  MTU:1500  Metric:1
          RX packets:404180 errors:0 dropped:0 overruns:0 frame:0
          TX packets:298225 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:3 
          RX bytes:475984839 (453.9 MiB)  TX bytes:36472112 (34.7 MiB)

seems the grep -v shouldnt be there either but it works - its a line i picked for displaying an ip adress on a linux machine and i need that to set up portforwarding once the dialup connection is established

anyway - the reason i put in the path was because i was trying to 'get' the same environment i get at the prompt - where the thing works ...
Last edited by vgersh99; 02-07-2009 at 12:44 PM.. Reason: fix the VB Codes: \code != /code
# 4  
Old 02-07-2009
ok, try this - put the script in debug mode (adding 'set -x') and see if your code behaves the way you think it should:
Code:
#!/bin/bash
set -x
# WHY exporting the PATH?

PATH="/usr/local/sbin:/usr/sbin:/sbin:/usr/local/bin:/bin:/usr/bin:$PATH"
iptables -F

dynip=$(ifconfig ppp0 | awk '/inet addr/ && !/127.0.0.1/{print substr($2, index($2, ":")+1)}')

# 5  
Old 02-07-2009
tx - was looking into that Smilie
# 6  
Old 02-07-2009
well that line works at the prompt :
Code:
root[ppp]# ip-up/nat
+ PATH=/usr/local/sbin:/usr/sbin:/sbin:/usr/local/bin:/bin:/usr/bin:/usr/local/sbin:/usr/sbin:/sbin:/usr/local/bin:/usr/bin:/bin:/usr/games/bin
+ iptables -F
++ ifconfig ppp0
++ awk '/inet addr/ && !/127.0.0.1/{print substr($2, index($2, ":")+1)}'
+ dynip=91.86.59.95
+ echo 91.86.59.95
+ iptables -t nat -A POSTROUTING -o ppp0 -j MASQUERADE
+ iptables -A FORWARD -i ppp0 -o eth0 -m state --state RELATED,ESTABLISHED -j ACCEPT
+ iptables -A FORWARD -i eth0 -o ppp0 -j ACCEPT
+ iptables -t nat -A PREROUTING -p tcp -i ppp0 -d 91.86.59.95 --dport 16913 -j DNAT --to 192.168.0.10:16913
+ iptables -A FORWARD -p tcp -i ppp0 -d 192.168.0.10 --dport 16913 -j ACCEPT
+ iptables -t nat -A PREROUTING -p udp -i ppp0 -d 91.86.59.95 --dport 16913 -j DNAT --to 192.168.0.10:16913
+ iptables -A FORWARD -p udp -i ppp0 -d 192.168.0.10 --dport 16913 -j ACCEPT
+ iptables -t nat -A PREROUTING -p tcp -i ppp0 -d 91.86.59.95 --dport 62601 -j DNAT --to 192.168.0.10:62601
+ iptables -A FORWARD -p tcp -i ppp0 -d 192.168.0.10 --dport 62601 -j ACCEPT
+ iptables -t nat -A PREROUTING -p udp -i ppp0 -d 91.86.59.95 --dport 62601 -j DNAT --to 192.168.0.10:62601
+ iptables -A FORWARD -p udp -i ppp0 -d 192.168.0.10 --dport 62601 -j ACCEPT
+ echo 91.86.59.95
+ date

this is probably also the right time to tell that pppd redirects script output to /dev/null - all i get in the log is :
Code:
Plugin pppoatm.so loaded.
PPPoATM plugin_init
PPPoATM setdevname_pppoatm - SUCCESS:8.35
Using interface ppp0
Connect: ppp0 <--> 8.35
CHAP authentication succeeded: CHAP authentication success, unit 1236
CHAP authentication succeeded
Can't execute /etc/ppp/ip-pre-up: Invalid argument
Cannot determine ethernet address for proxy ARP
local  IP address 91.86.59.95
remote IP address 91.86.32.1
primary   DNS address 212.65.63.218
secondary DNS address 212.224.255.252
Can't execute /etc/ppp/ip-up: Invalid argument

# 7  
Old 02-07-2009
tx for the help - it seems to be a pppd issue ...
i get the same error for this script :
Code:
#!/bin/bash
echo 'hello' >> ppp.log

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