BGP
What is Port 179?
Port 179 is used by the Border Gateway Protocol (BGP), the routing protocol that makes the internet work. Defined in RFC 4271, BGP is the protocol used by autonomous systems (AS) — large networks operated by ISPs, enterprises, and content providers — to exchange routing information and determine the best paths for internet traffic. BGP is classified as a path-vector protocol and maintains a table of IP network prefixes that indicate network reachability among autonomous systems. When you access any website, BGP routing decisions determine the path your packets take across the internet. BGP sessions are established over TCP connections on port 179, and peers exchange UPDATE messages to advertise new routes or withdraw old ones. BGP is critical infrastructure — routing errors or attacks can disrupt internet connectivity for millions of users.
Common Uses
- Internet routing between autonomous systems
- ISP peering and transit arrangements
- Enterprise multihomed internet connectivity
- Content delivery network route optimization
Technical Details
Copy-paste commands to check port 179 (BGP) from your terminal
Test connectivity
nc -zv example.com 179
curl -v --max-time 5 http://example.com:179/
telnet example.com 179
nmap -p 179 -sV example.com
(echo > /dev/tcp/example.com/179) 2>/dev/null && echo "open" || echo "closed"
Open port in firewall
sudo ufw allow 179/tcp
sudo iptables -A INPUT -p tcp --dport 179 -j ACCEPT
sudo firewall-cmd --permanent --add-port=179/tcp && sudo firewall-cmd --reload
Security Considerations
BGP hijacking is a serious threat where attackers announce routes for IP prefixes they don't own, redirecting traffic through their networks. RPKI (Resource Public Key Infrastructure) adds authentication to BGP announcements. Use MD5 authentication or TCP-AO for BGP sessions. Implement prefix filtering and route validation. BGP sessions should only be established with known, trusted peers.
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