Why is the BGP base on TCP 1027 rather than 179?
up vote
5
down vote
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Why is the BGP foreign address port 1027?
I use BGP to connect Router1 and Router2, but when I show the TCP progress:
Router1>show tcp brief
TCB Local Address Foreign Address (state)
4E976890 10.0.0.1.179 10.0.0.2.1027 ESTABLISHED
We say the BGP is based on TCP port 179. Why is Router2's BGP on port 1027?
cisco router bgp
edited Nov 26 at 10:09
jonathanjo
9,5211631
asked Nov 26 at 9:43
three-blocks
3306
add a comment |
up vote
5
down vote
favorite
Why is the BGP foreign address port 1027?
I use BGP to connect Router1 and Router2, but when I show the TCP progress:
Router1>show tcp brief
TCB Local Address Foreign Address (state)
4E976890 10.0.0.1.179 10.0.0.2.1027 ESTABLISHED
We say the BGP is based on TCP port 179. Why is Router2's BGP on port 1027?
cisco router bgp
edited Nov 26 at 10:09
jonathanjo
9,5211631
asked Nov 26 at 9:43
three-blocks
3306
add a comment |
up vote
5
down vote
favorite
up vote
5
down vote
favorite
Why is the BGP foreign address port 1027?
I use BGP to connect Router1 and Router2, but when I show the TCP progress:
Router1>show tcp brief
TCB Local Address Foreign Address (state)
4E976890 10.0.0.1.179 10.0.0.2.1027 ESTABLISHED
We say the BGP is based on TCP port 179. Why is Router2's BGP on port 1027?
cisco router bgp
edited Nov 26 at 10:09
jonathanjo
9,5211631
asked Nov 26 at 9:43
three-blocks
3306
Why is the BGP foreign address port 1027?
I use BGP to connect Router1 and Router2, but when I show the TCP progress:
Router1>show tcp brief
TCB Local Address Foreign Address (state)
4E976890 10.0.0.1.179 10.0.0.2.1027 ESTABLISHED
We say the BGP is based on TCP port 179. Why is Router2's BGP on port 1027?
cisco router bgp
cisco router bgp
edited Nov 26 at 10:09
jonathanjo
9,5211631
asked Nov 26 at 9:43
three-blocks
3306
edited Nov 26 at 10:09
jonathanjo
9,5211631
asked Nov 26 at 9:43
three-blocks
3306
edited Nov 26 at 10:09
jonathanjo
9,5211631
edited Nov 26 at 10:09
jonathanjo
9,5211631
edited Nov 26 at 10:09
jonathanjo
9,5211631
9,5211631
asked Nov 26 at 9:43
three-blocks
3306
asked Nov 26 at 9:43
three-blocks
3306
asked Nov 26 at 9:43
three-blocks
3306
3306
add a comment |
add a comment |
3 Answers
3
active
oldest
votes
up vote
9
down vote
accepted
One side of the connection will have an arbitrary port number, the other will be on 179.
Cisco Press "BGP Fundamentals" has a good explanation (link)
the neighbor with the higher IP address manages the connection. The router initiating the request uses a dynamic source port, but the destination port is always 179.
Example 1-1 shows an established BGP session using the command
show tcp briefto display the active TCP sessions between routers. Notice that the TCP source port is 179 and the destination port is 59884 on R1, and the ports are opposite on R2.
Example 1-1: Established BGP session
RP/0/0/CPU0:R1# show tcp brief | exc "LISTEN|CLOSED"
PCB VRF-ID Recv-Q Send-Q Local Address Foreign Address State
0x088bcbb8 0x60000000 0 0 10.1.12.1:179 10.1.12.2:59884 ESTAB
R2# show tcp brief
TCB Local Address Foreign Address (state)
EF153B88 10.1.12.2. 59884 10.1.12.1.179 ESTAB
This is just the same as any other TCP connection: the passive open side sits and waits on a well-known port number; the active open side uses an arbitary port. This makes it much easier to manage many-to-many TCP links.
answered Nov 26 at 9:58
jonathanjo
9,5211631
What's the correct way to protect these random ports in iptables?
– bswinnerton
Dec 1 at 16:57
Question is about Cisco routers, what are you wanting to protect withiptables?
– jonathanjo
Dec 1 at 17:39
add a comment |
up vote
4
down vote
TCP source vs. destination ports.
To give a different example: HTTP servers listen on TCP port 80. So when you are connecting to a web server, you will automatically use TCP/80 as the destination port. However, the source port is a random one above 1024.
The exact same thing happens with BGP - the client (the router initiating the connection) will connect to TCP destination port 179. But the source port for that connection will be a random high port.
answered Nov 26 at 14:45
Bogd
411
add a comment |
up vote
2
down vote
In general, the BGP use TCP 179 port as the BGP service. the client connect BGP service port there is no limit.
such as the SSH server use 22 as its port, there is no limit for the client port.
answered Nov 26 at 9:53
aircraft
544111
add a comment |
3 Answers
3
active
oldest
votes
3 Answers
3
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
9
down vote
accepted
One side of the connection will have an arbitrary port number, the other will be on 179.
Cisco Press "BGP Fundamentals" has a good explanation (link)
the neighbor with the higher IP address manages the connection. The router initiating the request uses a dynamic source port, but the destination port is always 179.
Example 1-1 shows an established BGP session using the command
show tcp briefto display the active TCP sessions between routers. Notice that the TCP source port is 179 and the destination port is 59884 on R1, and the ports are opposite on R2.
Example 1-1: Established BGP session
RP/0/0/CPU0:R1# show tcp brief | exc "LISTEN|CLOSED"
PCB VRF-ID Recv-Q Send-Q Local Address Foreign Address State
0x088bcbb8 0x60000000 0 0 10.1.12.1:179 10.1.12.2:59884 ESTAB
R2# show tcp brief
TCB Local Address Foreign Address (state)
EF153B88 10.1.12.2. 59884 10.1.12.1.179 ESTAB
This is just the same as any other TCP connection: the passive open side sits and waits on a well-known port number; the active open side uses an arbitary port. This makes it much easier to manage many-to-many TCP links.
answered Nov 26 at 9:58
jonathanjo
9,5211631
What's the correct way to protect these random ports in iptables?
– bswinnerton
Dec 1 at 16:57
Question is about Cisco routers, what are you wanting to protect withiptables?
– jonathanjo
Dec 1 at 17:39
add a comment |
up vote
9
down vote
accepted
One side of the connection will have an arbitrary port number, the other will be on 179.
Cisco Press "BGP Fundamentals" has a good explanation (link)
the neighbor with the higher IP address manages the connection. The router initiating the request uses a dynamic source port, but the destination port is always 179.
Example 1-1 shows an established BGP session using the command
show tcp briefto display the active TCP sessions between routers. Notice that the TCP source port is 179 and the destination port is 59884 on R1, and the ports are opposite on R2.
Example 1-1: Established BGP session
RP/0/0/CPU0:R1# show tcp brief | exc "LISTEN|CLOSED"
PCB VRF-ID Recv-Q Send-Q Local Address Foreign Address State
0x088bcbb8 0x60000000 0 0 10.1.12.1:179 10.1.12.2:59884 ESTAB
R2# show tcp brief
TCB Local Address Foreign Address (state)
EF153B88 10.1.12.2. 59884 10.1.12.1.179 ESTAB
This is just the same as any other TCP connection: the passive open side sits and waits on a well-known port number; the active open side uses an arbitary port. This makes it much easier to manage many-to-many TCP links.
answered Nov 26 at 9:58
jonathanjo
9,5211631
What's the correct way to protect these random ports in iptables?
– bswinnerton
Dec 1 at 16:57
Question is about Cisco routers, what are you wanting to protect withiptables?
– jonathanjo
Dec 1 at 17:39
add a comment |
up vote
9
down vote
accepted
up vote
9
down vote
accepted
One side of the connection will have an arbitrary port number, the other will be on 179.
Cisco Press "BGP Fundamentals" has a good explanation (link)
the neighbor with the higher IP address manages the connection. The router initiating the request uses a dynamic source port, but the destination port is always 179.
Example 1-1 shows an established BGP session using the command
show tcp briefto display the active TCP sessions between routers. Notice that the TCP source port is 179 and the destination port is 59884 on R1, and the ports are opposite on R2.
Example 1-1: Established BGP session
RP/0/0/CPU0:R1# show tcp brief | exc "LISTEN|CLOSED"
PCB VRF-ID Recv-Q Send-Q Local Address Foreign Address State
0x088bcbb8 0x60000000 0 0 10.1.12.1:179 10.1.12.2:59884 ESTAB
R2# show tcp brief
TCB Local Address Foreign Address (state)
EF153B88 10.1.12.2. 59884 10.1.12.1.179 ESTAB
This is just the same as any other TCP connection: the passive open side sits and waits on a well-known port number; the active open side uses an arbitary port. This makes it much easier to manage many-to-many TCP links.
answered Nov 26 at 9:58
jonathanjo
9,5211631
One side of the connection will have an arbitrary port number, the other will be on 179.
Cisco Press "BGP Fundamentals" has a good explanation (link)
the neighbor with the higher IP address manages the connection. The router initiating the request uses a dynamic source port, but the destination port is always 179.
Example 1-1 shows an established BGP session using the command
show tcp briefto display the active TCP sessions between routers. Notice that the TCP source port is 179 and the destination port is 59884 on R1, and the ports are opposite on R2.
Example 1-1: Established BGP session
RP/0/0/CPU0:R1# show tcp brief | exc "LISTEN|CLOSED"
PCB VRF-ID Recv-Q Send-Q Local Address Foreign Address State
0x088bcbb8 0x60000000 0 0 10.1.12.1:179 10.1.12.2:59884 ESTAB
R2# show tcp brief
TCB Local Address Foreign Address (state)
EF153B88 10.1.12.2. 59884 10.1.12.1.179 ESTAB
This is just the same as any other TCP connection: the passive open side sits and waits on a well-known port number; the active open side uses an arbitary port. This makes it much easier to manage many-to-many TCP links.
answered Nov 26 at 9:58
jonathanjo
9,5211631
edited Nov 26 at 10:06
answered Nov 26 at 9:58
jonathanjo
9,5211631
answered Nov 26 at 9:58
jonathanjo
9,5211631
answered Nov 26 at 9:58
jonathanjo
9,5211631
9,5211631
What's the correct way to protect these random ports in iptables?
– bswinnerton
Dec 1 at 16:57
Question is about Cisco routers, what are you wanting to protect withiptables?
– jonathanjo
Dec 1 at 17:39
add a comment |
What's the correct way to protect these random ports in iptables?
– bswinnerton
Dec 1 at 16:57
Question is about Cisco routers, what are you wanting to protect withiptables?
– jonathanjo
Dec 1 at 17:39
What's the correct way to protect these random ports in iptables?
– bswinnerton
Dec 1 at 16:57
What's the correct way to protect these random ports in iptables?
– bswinnerton
Dec 1 at 16:57
Question is about Cisco routers, what are you wanting to protect with
iptables?– jonathanjo
Dec 1 at 17:39
Question is about Cisco routers, what are you wanting to protect with
iptables?– jonathanjo
Dec 1 at 17:39
add a comment |
up vote
4
down vote
TCP source vs. destination ports.
To give a different example: HTTP servers listen on TCP port 80. So when you are connecting to a web server, you will automatically use TCP/80 as the destination port. However, the source port is a random one above 1024.
The exact same thing happens with BGP - the client (the router initiating the connection) will connect to TCP destination port 179. But the source port for that connection will be a random high port.
answered Nov 26 at 14:45
Bogd
411
add a comment |
up vote
4
down vote
TCP source vs. destination ports.
To give a different example: HTTP servers listen on TCP port 80. So when you are connecting to a web server, you will automatically use TCP/80 as the destination port. However, the source port is a random one above 1024.
The exact same thing happens with BGP - the client (the router initiating the connection) will connect to TCP destination port 179. But the source port for that connection will be a random high port.
answered Nov 26 at 14:45
Bogd
411
add a comment |
up vote
4
down vote
up vote
4
down vote
TCP source vs. destination ports.
To give a different example: HTTP servers listen on TCP port 80. So when you are connecting to a web server, you will automatically use TCP/80 as the destination port. However, the source port is a random one above 1024.
The exact same thing happens with BGP - the client (the router initiating the connection) will connect to TCP destination port 179. But the source port for that connection will be a random high port.
answered Nov 26 at 14:45
Bogd
411
TCP source vs. destination ports.
To give a different example: HTTP servers listen on TCP port 80. So when you are connecting to a web server, you will automatically use TCP/80 as the destination port. However, the source port is a random one above 1024.
The exact same thing happens with BGP - the client (the router initiating the connection) will connect to TCP destination port 179. But the source port for that connection will be a random high port.
answered Nov 26 at 14:45
Bogd
411
answered Nov 26 at 14:45
Bogd
411
answered Nov 26 at 14:45
Bogd
411
answered Nov 26 at 14:45
Bogd
411
411
add a comment |
add a comment |
up vote
2
down vote
In general, the BGP use TCP 179 port as the BGP service. the client connect BGP service port there is no limit.
such as the SSH server use 22 as its port, there is no limit for the client port.
answered Nov 26 at 9:53
aircraft
544111
add a comment |
up vote
2
down vote
In general, the BGP use TCP 179 port as the BGP service. the client connect BGP service port there is no limit.
such as the SSH server use 22 as its port, there is no limit for the client port.
answered Nov 26 at 9:53
aircraft
544111
add a comment |
up vote
2
down vote
up vote
2
down vote
In general, the BGP use TCP 179 port as the BGP service. the client connect BGP service port there is no limit.
such as the SSH server use 22 as its port, there is no limit for the client port.
answered Nov 26 at 9:53
aircraft
544111
In general, the BGP use TCP 179 port as the BGP service. the client connect BGP service port there is no limit.
such as the SSH server use 22 as its port, there is no limit for the client port.
answered Nov 26 at 9:53
aircraft
544111
answered Nov 26 at 9:53
aircraft
544111
answered Nov 26 at 9:53
aircraft
544111
answered Nov 26 at 9:53
aircraft
544111
544111
add a comment |
add a comment |
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