Problem with SSH local port forwarding

[Suhas!]

Hi all,

I am facing problem in SSH Port forwarding.

I want to forward the port 1812 running on server1 to server2. So I issue following command from server2

[root@server2 ~]# ssh -g -L 1812:server1:1812 server1
root@server1's password:
bind: Address already in use
Last login: Mon Jul 23 14:35:19 2007 from server2
[root@server1 ~]#

when I use above command without using -g option then it works fine. But I want the forwarded port to be used by other clients as well.

I have made sure that there is no service running on Server2 on port no. 1812. I have tried with many other ports as well.


Can anybody suggest me what to do to enable other clients to use forwarded port.

[Xenu]

run this on both server1 and server2

netstat -lpn

and look for anything listening on those ports.
you need to make sure that port is available
on the local machine too.l

according to the man page you should also
specify bind address

-L [bind_address:]port:host:hostport

this example worked fine for me :

ssh -g -L 192.168.0.1:1919:192.168.0.2:31337 root@192.168.0.2


this listened on my local machine (192.168.0.1) on port 1919 to
remote server (192.168.0.2) running nc on port 31337
i could then telnet to port 1919 on 192.168.0.1 using my windows box
worked ok.

[Suhas!]

Thanks for the reply.

Heres my netstat -lpn's output for both servers :

Server1 (IP Address 10.8.59.59)

[root@server1 ~]# netstat -lpn
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address Stat e PID/Program name
tcp 0 0 0.0.0.0:199 0.0.0.0:* LIST EN 2013/snmpd
tcp 0 0 0.0.0.0:111 0.0.0.0:* LIST EN 1970/portmap
tcp 0 0 10.8.59.59:8080 0.0.0.0:* LIST EN 2090/(squid)
tcp 0 0 :::22 :::* LIST EN 2059/sshd
udp 0 0 0.0.0.0:161 0.0.0.0:* 2013/snmpd
udp 0 0 0.0.0.0:3130 0.0.0.0:* 2090/(squid)
udp 0 0 0.0.0.0:3401 0.0.0.0:* 2090/(squid)
udp 0 0 0.0.0.0:111 0.0.0.0:* 1970/portmap
udp 0 0 0.0.0.0:33532 0.0.0.0:* 2090/(squid)
Active UNIX domain sockets (only servers)
Proto RefCnt Flags Type State I-Node PID/Program name Pat h
unix 2 [ ACC ] STREAM LISTENING 5635 2137/winbindd /tm p/.winbindd/pipe
unix 2 [ ACC ] STREAM LISTENING 5637 2137/winbindd /va r/lib/samba/winbindd_privileged/pipe
[root@server1 ~]#

and Server2 (IP Address 10.8.59.60)

[root@server2 ~]# netstat -lpn
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address Stat e PID/Program name
tcp 0 0 127.0.0.1:1444 0.0.0.0:* LIST EN 2593/iwssd
tcp 0 0 0.0.0.0:199 0.0.0.0:* LIST EN 2254/snmpd
tcp 0 0 0.0.0.0:111 0.0.0.0:* LIST EN 2211/portmap
tcp 0 0 0.0.0.0:8081 0.0.0.0:* LIST EN 2593/iwssd
tcp 0 0 0.0.0.0:21 0.0.0.0:* LIST EN 3043/isftpd
tcp 0 0 0.0.0.0:5432 0.0.0.0:* LIST EN 2565/postmaster
tcp 0 0 ::ffff:127.0.0.1:8005 :::* LIST EN 3090/java
tcp 0 0 ::ffff:127.0.0.1:5963 :::* LIST EN 24472/java
tcp 0 0 :::1812 :::* LIST EN 3090/java
tcp 0 0 :::22 :::* LIST EN 2300/sshd
tcp 0 0 :::5432 :::* LIST EN 2565/postmaster
udp 0 0 0.0.0.0:39189 0.0.0.0:* 26983/snmpwalk
udp 0 0 0.0.0.0:161 0.0.0.0:* 2254/snmpd
udp 0 0 0.0.0.0:111 0.0.0.0:* 2211/portmap
Active UNIX domain sockets (only servers)
Proto RefCnt Flags Type State I-Node PID/Program name Pat h
unix 2 [ ACC ] STREAM LISTENING 5218 2565/postmaster /tm p/.s.PGSQL.5432
[root@server2 ~]#


As you can see there is no port 1812 running on server1, and it is running on server2 (Which I want to forward to server1).

Also I tried to use the same command as you said :

[root@Server1 ~]# ssh -g -L 10.8.59.59:1919:10.8.59.60:1812 root@10.8.59.60
Bad forwarding specification '10.8.59.59:1919:10.8.59.60:1812'
usage: ssh [-1246AaCfghkMNnqsTtVvXxY] [-b bind_address] [-c cipher_spec]
[-D port] [-e escape_char] [-F configfile] [-i identity_file]
[-L port:host:hostport] [-l login_name] [-m mac_spec] [-o option]
[-p port] [-R port:host:hostport] [-S ctl] [user@]hostname [command]



I found that to specify bind address the option is -b, when I used it I got following error.

[root@server1 ~]# ssh -g -L 1919:10.8.59.60:1812 -b 10.8.59.59 root@10.8.59.60
root@10.8.59.60's password:
bind: Address already in use
Last login: Tue Jul 24 15:20:10 2007 from 10.8.97.27


I am still confused why is it not working?

I am now looking for port forwarding using IPTABLES. Do you have any idea about IPTABLES port forwarding?


Thanks in advance!!!