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manu_leo
Guru
Guru


Joined: 20 Jan 2014
Posts: 499
Location: India

PostPosted: Tue Oct 20, 2020 3:53 am    Post subject: Telnet not working Reply with quote

Hi Experts, I have run into a very weird issue . I have an application called as exasock and when I am prepending it with telnet -b option, my communication seems to break. This is what I mean -

10.230.54.43 is IP on my Server 10G NIC and there is no other IP.
172.28.124.30 is Remote IP (Exchange) and 10990 is the Port.

Code:
# telnet -b 10.230.54.43 172.28.124.30 10990
Trying 172.28.124.30...
Connected to 172.28.124.30.
Escape character is '^]'.
Connection closed by foreign host.


Code:
# exasock telnet 172.28.124.30 10990
Trying 172.28.124.30...
Connected to 172.28.124.30.
Escape character is '^]'.
Connection closed by foreign host.


Code:
# exasock telnet -b 10.230.54.43 172.28.124.30 10990
Trying 172.28.124.30...
[/code]

When I use Exasock with telnet -b option, it does not work. Nothing in tcpdump


Ifconfig -
Code:
eno1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.101.81  netmask 255.255.255.0  broadcast 192.168.101.255
        inet6 fe80::46a8:42ff:fe24:ac0f  prefixlen 64  scopeid 0x20<link>
        ether 44:a8:42:24:ac:0f  txqueuelen 1000  (Ethernet)
        RX packets 827026  bytes 75687087 (72.1 MiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 503710  bytes 54605607 (52.0 MiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
        device interrupt 69 

enp4s0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 10.230.54.43  netmask 255.255.255.128  broadcast 10.230.54.127
        inet6 fe80::663f:5fff:fe01:5816  prefixlen 64  scopeid 0x20<link>
        ether 64:3f:5f:01:58:16  txqueuelen 1000  (Ethernet)
        RX packets 153513  bytes 33332818 (31.7 MiB)
        RX errors 0  dropped 21714  overruns 0  frame 0
        TX packets 20866  bytes 1740284 (1.6 MiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

enp4s0d1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 100.100.100.12  netmask 255.255.255.0  broadcast 100.100.100.255
        inet6 fe80::663f:5fff:fe01:5817  prefixlen 64  scopeid 0x20<link>
        ether 64:3f:5f:01:58:17  txqueuelen 1000  (Ethernet)
        RX packets 23741  bytes 1639896 (1.5 MiB)
        RX errors 0  dropped 21862  overruns 0  frame 0
        TX packets 186  bytes 9252 (9.0 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
        inet 127.0.0.1  netmask 255.0.0.0
        inet6 ::1  prefixlen 128  scopeid 0x10<host>
        loop  txqueuelen 1000  (Local Loopback)
        RX packets 1374  bytes 70524 (68.8 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 1374  bytes 70524 (68.8 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0


routing table -
Code:
# route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         192.168.101.2   0.0.0.0         UG    0      0        0 eno1
10.230.54.0     0.0.0.0         255.255.255.128 U     0      0        0 enp4s0
100.100.100.0   0.0.0.0         255.255.255.0   U     0      0        0 enp4s0d1
172.18.0.0      10.230.54.1     255.255.0.0     UG    0      0        0 enp4s0
172.19.0.0      10.230.54.1     255.255.0.0     UG    0      0        0 enp4s0
172.28.124.0    10.230.54.1     255.255.255.0   UG    0      0        0 enp4s0
192.168.101.0   0.0.0.0         255.255.255.0   U     0      0        0 eno1


I am completely out of ideas as to why would this happen - when I am using the source with exasock, it stops working. When I remove the source and use exasock without source, it works fine. Is there something in the kernel or sysctl parameters that needs to be modified or changed.

Thanks in advance.
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mike155
Advocate
Advocate


Joined: 17 Sep 2010
Posts: 2484
Location: Frankfurt, Germany

PostPosted: Tue Oct 20, 2020 12:34 pm    Post subject: Reply with quote

Why do you want to use option -b? I have never used it.
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