140 pts.
 Telnet to a Cisco 1700 Router
I have a cisco 1700 router, when I telnet to it from a remote site, it comes back saying "connection closed by remote host". I have checked the vty lines and verified the password. even more interesting is that when I telnet to it when directly connected via ethernet, it allows me to connect. remotely, I can telnet to the switch where it's connected to but not the the router itself.

Software/Hardware used:
ASKED: April 1, 2009  11:25 AM
UPDATED: July 6, 2010  4:49 AM

Answer Wiki:
First u see the reachability from ur host ip address to router. If it is possible ti reach there & see ACL in ur router. whethere it is permitted or denied from ur system. Then check ur vty terminal configuration : Router(config)#line vty 0 4 Router(config-line)#password cisco Router(config-line)#login whether telnet/ssh is allowed on ur router or not. Router(config-line)#transport input telnet ssh either u can configure both of them at a time or any one at a time, it depend on ur desire. Plz pardon me, if i left anything overhere to tell u. You need to check NAT translations. Your access-list for NAT most likely looks like below: access-list 100 per ip any any the source "any" is causing problem. Specify your source address/network(s) in NAT ACL to be site specific. For example, if your LAN is 10.10.10.0/24, use ACL below for NAT. access-list 100 per ip 10.10.10.0 0.0.0.255 any Hope this helps.
Last Wiki Answer Submitted:  July 6, 2010  4:49 am  by  Bhupendra   205 pts.
All Answer Wiki Contributors:  Bhupendra   205 pts. , Bahlezi   140 pts. , Labnuke99   32,645 pts.
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Try a tracert from both devices to determine if the traffic is not making it back to the remote telnet host.

 0 pts.

 

You are seeing ‘connection closed by remote host’ so you are definitely connecting to the telnet port of some device. Might not be the WAN interface of that 1700 router however!

Quick thing you can do is use nmap to identify the router from the remote site. For example nmap -O {IP Address of WAN interface of 1700}.

If you can confirm that the IP address that you are attempting to connect to from the remote site is in fact the WAN interface on the 1700 then you need to logon to that route from the LAN side and check what access list are defined on inbound traffic from the WAN.

Let me know how you go.

 35 pts.

 

check your on vty port – login commad is entered or not.
If you enter password and not login command then router doesn’t give telnet access.

 55 pts.